Major interaction on record — check this product against your medications before combining. Based on 8 of 9 ingredients. Check your meds →
Dietary supplement

On Guard + Ingredients & Drug Interactions

by doTERRA

On Guard + label
See full label image
Softgel Capsule Category: Botanical
Most serious interaction: Major
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking On Guard + against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Major

On Guard + is a dietary supplement by doTERRA with 9 active ingredients. Its ingredients are commonly taken for vitamin c source, digestive upset, stress and relaxation (aromatherapy).Based on those ingredients, 1,307 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Black Pepper seed Oil, Clove bud Oil, Eucalyptus leaf Oil. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against On Guard + by doTERRA

Ask about any prescription or over-the-counter medication and we check it for interactions with On Guard + by doTERRA — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
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Computed from our clinical databases

HelloPharmacist Scorecard of On Guard + by doTERRA

Four independent checks of what is known — a summary of the available information, not a grade of the product itself.

Evidence for Intended Use
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

The stated purpose hasn't been mapped to our evidence data yet.

Why this rating?
  • We haven't mapped this product's purpose to our evidence data yet — it'll be graded on the next content refresh.
Ingredient Transparency
Low

Most active ingredients don't disclose an individual amount — you can't tell how much of each you're getting.

Why this rating?
  • The label discloses an exact amount for 0 of its 9 active ingredients.
  • “On Guard + Protective Blend” is a proprietary blend — the label gives one combined amount (120 mg) without saying how much of each component you get.
Known Interaction Concern
Major identified

At least one ingredient has a documented Major-severity interaction. Check your medications for a personalized result.

Why this rating?
  • 8 of the 8 matched ingredients can interact with medications — Rosemary, Clove, Lemon Balm, Oregano, Eucalyptus, among others.
  • The most serious interaction on file is rated Major.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; diabetes medications; lithium.
  • For scale: 1,308 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.
Safety Information
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 8 of the 8 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 8 of 8.
  • General safety write-ups exist for 8 of 8.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

HelloPharmacist summaryFormula with limited ingredient disclosure with no assessable stated purpose. Major medication interactions have been identified, and safety information is well characterized.

Assessment coverage: 9 of 9 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated May 28, 2019.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about On Guard +, straight from the product label.

Brand doTERRA
Net contents 60 Softgel(s)
Market status Off market
Date entered into DSLD May 28, 2019
DSLD ID 202990
Product type Botanical
Supplement form Softgel Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for On Guard + by doTERRA, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
1 Softgel(s)
Maximum serving Sizes:
1 Softgel(s)
Servings per container
60
IngredientAmount% DV
wild Orange peel Oil0 NP--
Cinnamon bark Oil0 NP--
Rosemary leaf Oil0 NP--
Clove bud Oil0 NP--
Oregano leaf Oil0 NP--
Cinnamon leaf Oil0 NP--
On Guard + Protective Blend120 mg--
Black Pepper seed Oil0 NP--
Eucalyptus leaf Oil0 NP--
Melissa Oil0 NP--

Other ingredients: extra virgin Olive Oil, non-GMO modified Corn Starch, Glycerin, Carrageenan, purified Water, Maltitol

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

Protective Blend Softgels

FDA Statement of Identity

Dietary Supplement

Formula

doTERRA On Guard + Softgels contain the proprietary doTERRA On Guard essential oil blend along with Black Pepper, Oregano, and Melissa for additional immune support when needed.

Suggested/Recommended/Usage/Directions

Directions for use: Take 1 or more softgels as needed to promote healthy immune function.

Precautions

Caution: Keep out of reach of children.

If pregnant, nursing, or under a doctor's care, consult your physician.

Storage

Store in a cool, dry place.

FDA Disclaimer Statement

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

General

v5 35420001

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

On Guard + by doTERRA label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

On Guard + label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in On Guard + by doTERRA

These are the 9 active ingredients this product is made of. Select any to open its full monograph.

Serving size1 Softgel(s) Dosage formSoftgel Capsule Servings per container60 Amounts shown are per serving.

Most supplement products combine several ingredients, and a medication can interact with the product through any one of them. Each ingredient below shows whether it has known drug interactions.

Other (inactive) ingredients: Extra virgin Olive Oil, Non-GMO modified Corn Starch, Glycerin, Carrageenan, Purified Water, Maltitol. These complete the product’s ingredient list but are not active constituents.

Interaction report

On Guard + by doTERRA Drug Interactions

On Guard + contains 9 ingredients, and 8 of them have known drug interactions. Altogether they interact with 1,307 medications. Here’s the picture, then you can look up your own drug.

Want to check YOUR meds against On Guard +?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
1,307Drugs
48 Major 1,259 Moderate

Ingredients driving the most interactions

Black Pepper seed Oil 1,019
Clove bud Oil 977
Eucalyptus leaf Oil 878
Cinnamon bark Oil 442
Rosemary leaf Oil 372

Individual Drug Interactions

The ingredients in On Guard + interact with 1,307 drugs. Click any drug to see the details.

8 of the 9 ingredients in On Guard + interact with drugs. Each result below shows which ingredient is responsible. Black Pepper seed Oil Clove bud Oil Eucalyptus leaf Oil Cinnamon bark Oil Rosemary leaf Oil Melissa Oil wild Orange peel Oil Oregano leaf Oil

Each ingredient & the kinds of drugs it affects

For each ingredient in On Guard + with known interactions, here are the types of medications they can affect. Open any type for the detail — or search your exact drug in the checker above.

Black Pepper seed Oil17 drug types · 1,019 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, black pepper might increase the risk of bleeding when taken with antiplatelet or anticoagulant drugs.
In vitro research shows that piperine, a constituent of black pepper, seems to inhibit platelet aggregation. This has not been reported in humans.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, black pepper might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal research shows that piperine, a constituent of black pepper, can reduce blood glucose levels. Monitor blood glucose levels closely. Dose adjustments might be necessary.

Likelihood Possible Evidence D
Atorvastatin (Lipitor)

Theoretically, black pepper might increase blood levels of atorvastatin.
Animal research shows that taking piperine, a constituent of black pepper, 35 mg/kg can increase the maximum serum concentration of atorvastatin three-fold. This has not been reported in humans.

Likelihood Possible Evidence D
Cyclosporine (Neoral, Sandimmune)

Theoretically, black pepper might increase the effects and side effects of cyclosporine.
In vitro research shows that piperine, a constituent of black pepper, increases the bioavailability of cyclosporine. This has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, black pepper might increase levels of drugs metabolized by CYP2D6.
In vitro research suggests that some constituents of black pepper inhibit CYP2D6. This has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, black pepper might increase levels of drugs metabolized by CYP3A4.
In vitro research and pharmacokinetic simulation data suggest that piperine, a constituent of black pepper, as well as the pepper fruit seem to inhibit CYP3A4. This has not been reported in humans.

Likelihood Possible Evidence D
Lithium

Theoretically, black pepper might increase blood levels of lithium due to its diuretic effects. The dose of lithium might need to be reduced.
Black pepper is thought to have diuretic properties.

Likelihood Probable Evidence D
Nevirapine (Viramune)

Black pepper might increase blood levels of nevirapine.
Clinical research shows that piperine, a constituent of black pepper, increases the plasma concentration of nevirapine. However, no adverse effects were observed in this study.

Likelihood Probable Evidence D
P-Glycoprotein Substrates

Theoretically, black pepper might increase levels of P-glycoprotein substrates.
In vitro research shows that piperine, a constituent of black pepper, seems to inhibit P-glycoprotein.

Likelihood Possible Evidence D
Pentobarbital (Nembutal)

Theoretically, black pepper might increase the sedative effects of pentobarbital.
Animal research shows that piperine, a constituent of black pepper, increases pentobarbital-induced sleeping time.

Likelihood Possible Evidence D
Phenytoin (Dilantin)

Black pepper might increase blood levels of phenytoin.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption, slow elimination, and increase levels of phenytoin. Taking a single dose of black pepper 1 gram along with phenytoin seems to double the serum concentration of phenytoin. Consuming a soup with black pepper providing piperine 44 mg/200 mL of soup along with phenytoin also seems to increase phenytoin levels when compared with consuming the same soup without black pepper.

Likelihood Possible Evidence B
Propranolol (Inderal)

Black pepper might increase blood levels of propranolol.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of propranolol.

Likelihood Possible Evidence B
Rifampin (Rifadin)

Black pepper might increase blood levels of rifampin.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and serum levels of rifampin.

Likelihood Possible Evidence B
Theophylline

Black pepper might increase blood levels of theophylline.
Clinical research shows that piperine, a constituent of black pepper, seems to increase absorption and slow elimination of theophylline.

Likelihood Possible Evidence D
Amoxicillin (Amoxil, Trimox)

Theoretically, black pepper might increase the effects and side effects of amoxicillin.
Animal research shows that taking piperine, a constituent of black pepper, with amoxicillin increases plasma levels of amoxicillin. This has not been reported in humans.

Likelihood Possible Evidence D
Carbamazepine (Tegretol)

Theoretically, black pepper might increase blood levels of carbamazepine, potentially increasing the effects and side effects of carbamazepine.
One clinical study in patients taking carbamazepine 300 mg or 500 mg twice daily shows that taking a single 20 mg dose of purified piperine, a constituent of black pepper, increases carbamazepine levels. Piperine may increase carbamazepine absorption by increasing blood flow to the GI tract, increasing the surface area of the small intestine, or inhibiting cytochrome P450 3A4 (CYP3A4) in the gut wall. Absorption was significantly increased by 7-10 mcg/mL/hour. The time to eliminate carbamazepine was also increased by 4-8 hours. Although carbamazepine levels were increased, this did not appear to increase side effects. In vitro research also shows that piperine can increase carbamazepine levels by 11% in a time-dependent manner.

Likelihood Possible Evidence B
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, black pepper might decrease levels and clinical effects of drugs metabolized by CYP1A2.
In vitro research suggests that black pepper induces CYP1A2. This has not been reported in humans.

Likelihood Possible Evidence D
Black Pepper seed Oil full monograph & interactions

Clove bud Oil7 drug types · 977 drugs

Antidiabetes Drugs

Theoretically, concomitant use of clove extracts with antidiabetes drugs might increase the risk of hypoglycemia.
Clinical and laboratory research suggest that polyphenol extracts from clove flower buds might lower blood glucose levels. Dosing adjustments for insulin or oral hypoglycemic agents may be necessary when taken with clove. Monitor blood glucose levels closely.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, concomitant use of clove may increase levels of drugs metabolized by CYP1A2.
In vitro research shows that eugenol, the principal constituent of clove, can inhibit CYP1A2 in a dose-dependent manner,. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, concomitant use of clove may increase levels of drugs metabolized by CYP2C9.
In vitro research shows that eugenol, the principal constituent of clove, inhibits CYP2C9 in a dose-dependent manner. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, concomitant use of clove may increase levels of drugs metabolized by CYP2D6.
In vitro research shows that eugenol, the principal constituent of clove, can inhibit CYP2D6 in a dose-dependent manner. This effect has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, concomitant use of clove may increase levels of drugs metabolized by CYP3A4.
In vitro research shows that eugenol, the principal constituent of clove, can inhibit CYP3A4 in a dose-dependent manner. This effect has not been reported in humans.

Likelihood Possible Evidence D
Anticoagulant/Antiplatelet Drugs

Theoretically, clove oil may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
Laboratory research suggests that eugenol, a constituent of clove, has antiplatelet activity. This interaction has not been reported in humans.

Likelihood Unlikely Evidence D
Ibuprofen (Advil, Others)

Theoretically, topical application of clove oil with ibuprofen might increase the absorption and side effects of topical ibuprofen.
Laboratory research shows that topical application of clove oil increases the absorption of topical ibuprofen. This interaction has not been reported in humans.

Likelihood Possible Evidence D
Clove bud Oil full monograph & interactions

Eucalyptus leaf Oil7 drug types · 878 drugs

Amphetamines

Theoretically, inhaling eucalyptol may reduce the effectiveness of amphetamines.
Animal research suggests that inhaling eucalyptol may reduce the levels of amphetamines in the blood.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, eucalyptus leaf might increase the risk of hypoglycemia.
Animal research suggests that eucalyptus leaf might have hypoglycemic activity, and might have additive effects when used with antidiabetes drugs.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, eucalyptus might increase the levels of CYP1A2 substrates.
In vitro research suggests that eucalyptus oil might inhibit CYP1A2, although this has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C19 (Cyp2C19) Substrates

Theoretically, eucalyptus might increase the levels of CYP2C19 substrates.
In vitro research suggests that eucalyptus oil might inhibit CYP2C19, although this has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, eucalyptus might increase the levels of CYP2C9 substrates.
In vitro research suggests that eucalyptus oil might inhibit CYP2C9, although this has not been reported in humans.

Likelihood Possible Evidence D
Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, eucalyptus might increase the levels of CYP3A4 substrates.
In vitro research suggests that eucalyptus oil might inhibit CYP3A4, although this has not been reported in humans.

Likelihood Possible Evidence D
Pentobarbital (Nembutal)

Theoretically, inhaling eucalyptol might reduce the effectiveness of pentobarbital.
Animal research suggests that inhaling eucalyptol reduces the level of pentobarbital that reaches the brain.

Likelihood Possible Evidence D
Eucalyptus leaf Oil full monograph & interactions

Cinnamon bark Oil2 drug types · 442 drugs

Antidiabetes Drugs

Theoretically, cassia cinnamon may have additive effects with antidiabetes drugs.
Cassia cinnamon may lower blood glucose levels, and have additive effects in patients treated with antidiabetic agents. Dose adjustments to diabetes medications might be necessary.

Likelihood Possible Evidence B
Hepatotoxic Drugs

Theoretically, large doses of cassia cinnamon might cause additive effects when used with hepatotoxic drugs.
There is some concern that ingesting large amounts of cassia cinnamon for an extended duration might cause hepatotoxicity in some people. Cassia cinnamon contains coumarin, which can cause hepatotoxicity in animal models. In humans, very high doses of coumarin from 50-7000 mg/day can result in hepatotoxicity that resolves when coumarin use is discontinued. Lower amounts might also cause liver problems in sensitive people, such as those with liver disease or those taking potentially hepatotoxic agents.

Likelihood Possible Evidence D
Cinnamon bark Oil full monograph & interactions

Rosemary leaf Oil6 drug types · 372 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, rosemary may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro and animal research suggests that rosemary inhibits platelet aggregation.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, taking rosemary with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research shows that rosemary extract can decrease blood glucose levels in diabetic models. However, research in humans is conflicting. Although rosemary powder decreased blood glucose levels in healthy adults, no change in blood glucose levels was seen in adults with type 2 diabetes, most of whom were taking antidiabetes drugs.

Likelihood Possible Evidence B
Aspirin

Theoretically, rosemary might have additive effects with salicylate-containing drugs such as aspirin.
Rosemary is reported to contain salicylates.

Likelihood Possible Evidence D
Choline Magnesium Trisalicylate (Trilisate)

Theoretically, rosemary might have additive effects with salicylate-containing drugs such as choline magnesium trisalicylate.
Rosemary is reported to contain salicylate.

Likelihood Possible Evidence D
Salsalate (Disalcid)

Theoretically, rosemary might have additive effects with salicylate-containing drugs such as salsalate.
Rosemary is reported to contain salicylate.

Likelihood Possible Evidence D
Cytochrome P450 1A2 (Cyp1A2) Substrates

Theoretically, rosemary might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that rosemary induces CYP1A2 enzymes. This effect has not been reported in humans.

Likelihood Unlikely Evidence D
Rosemary leaf Oil full monograph & interactions

Melissa Oil2 drug types · 264 drugs

Cns Depressants

Theoretically, concomitant use of lemon balm might have additive effects with CNS depressant drugs.
Lemon balm seems to have CNS depressant activity in animals and in humans.

Likelihood Possible Evidence B
Thyroid Hormone

Theoretically, lemon balm might interfere with thyroid hormone replacement therapy.
In vitro, constituents of lemon balm extract bind to thyroid stimulating hormone (TSH), preventing TSH receptor-binding and leading to the inhibition of TSH-stimulated adenylate cyclase activity. In animals, lemon balm extract has been shown to decrease levels of circulating TSH and inhibit thyroid secretion.

Likelihood Possible Evidence D
Melissa Oil full monograph & interactions

wild Orange peel Oil7 drug types · 246 drugs

Celiprolol (Celicard)

Consuming sweet orange with celiprolol can decrease oral absorption of celiprolol.
A pharmacokinetic study in healthy volunteers shows that celiprolol levels, after a single dose of 100 mg, are decreased by up to 90% in people who drink sweet orange juice 200 mL three times daily. It's not known if lower consumption of sweet orange juice will have the same effect. Theoretically, this occurs due to short-term inhibition of organic anion transporting polypeptide (OATP). Recommend separating drug administration and consumption of sweet orange by at least 4 hours.

Likelihood Likely Evidence B
Ivermectin (Stromectol, Others)

Consuming sweet orange juice with ivermectin can decrease the oral absorption of ivermectin.
A pharmacokinetic study in healthy volunteers shows that taking ivermectin orally with sweet orange juice 750 mL over 4 hours reduces the bioavailability of ivermectin. This effect does not seem to be related to effects on P-glycoprotein. The effect on ivermectin is more pronounced in males compared to females.

Likelihood Likely Evidence B
Organic Anion-Transporting Polypeptide Substrates (Oatp)

Consuming sweet orange juice can decrease oral absorption of OATP substrates. Separate administration by at least 4 hours.
Clinical research shows that consuming sweet orange juice inhibits OATP, which reduces bioavailability of oral drugs that are substrates of OATP. For example, sweet orange juice decreases bioavailability of fexofenadine, a substrate of OATP, by about 72% and of celiprolol, another OATP substrate, by up to 90%. Since sweet orange juice seems to affect OATP for a short time, recommend separating drug administration and consumption of sweet orange juice by at least 4 hours.

Likelihood Likely Evidence B
Pravastatin (Pravachol)

Consuming sweet orange juice with pravastatin can increase the absorption of pravastatin.
A small pharmacokinetic study in healthy volunteers shows that consuming sweet orange juice 800 mL over 3 hours, including before, during, and after taking pravastatin 10 mg, increases pravastatin levels by about 149%, without affecting pravastatin elimination. Theoretically this effect might be due to modulation of organic anion transporting polypeptides (OATPs) by sweet orange juice. Sweet orange juice does not seem to affect simvastatin levels, but it is not known if sweet orange affects any of the other statins.

Likelihood Likely Evidence B
Fexofenadine (Allegra)

Consuming sweet orange juice with fexofenadine can decrease oral absorption of fexofenadine.
Clinical research shows that coadministration of sweet orange juice 1200 mL decreases bioavailability of fexofenadine by about 72%. In an animal model, sweet orange juice decreased bioavailability of fexofenadine by 31%. Fexofenadine manufacturer data indicates that concomitant administration of sweet orange juice and fexofenadine results in larger wheal and flare sizes in research models. This suggests that sweet orange reduces the clinical response to fexofenadine. Theoretically, this occurs due to short-term inhibition of organic anion transporting polypeptide (OATP). Recommend separating drug administration and consumption of sweet orange by at least 4 hours.

Likelihood Likely Evidence B
P-Glycoprotein Substrates

Sweet orange juice seems to modulate P-glycoprotein (P-gp), which might affect the blood levels of P-gp substrates.
Animal and in vitro research suggest that orange juice extract inhibits drug efflux by P-gp, increasing absorption and levels of P-gp substrates. In contrast, pharmacokinetic research in humans shows that drinking large amounts of sweet orange juice decreases absorption and levels of the P-gp substrate celiprolol. This suggests that orange juice actually induces drug efflux by P-gp or affects drug levels by another mechanism such as inhibiting the gut drug transporter called organic anion transporting polypeptide (OATP). Until more is known, sweet orange juice should be used cautiously in people taking P-gp substrates.

Likelihood Possible Evidence B
Quinolone Antibiotics

Calcium-fortified sweet orange juice might reduce quinolone absorption.
Calcium binds to quinolones in the gut. Theoretically, the calcium in certain fortified orange juices can also bind to quinolone antibiotics and reduce their absorption and levels.

Likelihood Possible Evidence D
wild Orange peel Oil full monograph & interactions

Oregano leaf Oil2 drug types · 208 drugs

Anticoagulant/Antiplatelet Drugs

Theoretically, oregano might increase the risk of bleeding when taken with anticoagulant or antiplatelet drugs.
In vitro research shows that aristolochic acid isolated from oregano leaves has antithrombin activity. It has also been reported that oregano oil inhibits arachidonic acid-induced, and ADP-induced, platelet aggregation.

Likelihood Possible Evidence D
Antidiabetes Drugs

Theoretically, oregano might increase the risk for hypoglycemia when taken with antidiabetes drugs.
In vitro and animal research shows that oregano extracts might lower blood glucose levels.

Likelihood Possible Evidence D
Oregano leaf Oil full monograph & interactions
The maker

Brand information

Manufacturer and brand details for On Guard +, from the product label.

doTERRA

See all doTERRA products
Name
doTERRA Intl, LLC
Street Address
389 South 1300 West
City
Pleasant Grove
State
UT
ZipCode
84062
Pharmacist Counseling Corner

On Guard + by doTERRA: Common Questions

Does On Guard + by doTERRA interact with any medications?
Yes. Based on its ingredients, On Guard + has a known interaction with 1,307 medications, including 48 rated major. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
On Guard + contains 9 active ingredients, and an interaction can come from any of them. We check every ingredient, combine the results into one list per medication, and show which ingredient and mechanism is responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

On Guard + label
Go deeper

The Full Monographs Behind On Guard +’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Sweet Orange

Interacts with 246 drugs

Sweet orange is a common citrus fruit that is a good source of vitamin C, fiber, and antioxidants, and is enjoyed as a food worldwide. Its peel and essential oil are used in aromatherapy and...

Read the full Sweet Orange monograph → Herb & supplement monograph

Cassia Cinnamon

Interacts with 442 drugs

Cassia cinnamon is the common, inexpensive cinnamon used in cooking, and it is also taken as a supplement, most often for blood sugar support. The evidence for its health benefits is mixed a...

Read the full Cassia Cinnamon monograph → Herb & supplement monograph

Rosemary

Interacts with 372 drugs

Rosemary is a fragrant Mediterranean herb that is safe and flavorful in normal food amounts. Some early research suggests possible benefits for memory, mood, and hair growth, but the evidenc...

Read the full Rosemary monograph → Herb & supplement monograph

Clove

Interacts with 977 drugs

Clove is a common cooking spice that is also used in traditional medicine, especially as a topical numbing agent for tooth pain thanks to its main compound, eugenol. Food amounts are general...

Read the full Clove monograph → Herb & supplement monograph

Oregano

Interacts with 208 drugs

Oregano is a common Mediterranean cooking herb that is also sold as a concentrated oil or supplement, often standardized for a compound called carvacrol. While lab studies suggest it may hav...

Read the full Oregano monograph → Herb & supplement monograph

Black Pepper

Interacts with 1,019 drugs

Black pepper is a common kitchen spice that is generally safe in the amounts used in food. Its extract, piperine, is mostly added to supplements to help the body absorb other ingredients (li...

Read the full Black Pepper monograph → Herb & supplement monograph

Eucalyptus

Interacts with 878 drugs

Eucalyptus is best known for its strong-smelling oil used in vapor rubs, inhalants, and lozenges to ease coughs and congestion. It may provide mild, short-term relief of cold symptoms, but t...

Read the full Eucalyptus monograph → Herb & supplement monograph

Lemon Balm

Interacts with 264 drugs

Lemon balm is a gentle, lemon-scented mint-family herb traditionally used to ease stress, support sleep, and calm digestion, and topically for cold sores. Early studies are promising but gen...

Read the full Lemon Balm monograph →
Sources

Sources & How We Checked

On Guard +'s label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 159 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Sweet Orange 17 references
  1. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  2. FDA, CFSAN. FDA-approved potassium health claim notification for potassium containing foods. 2000. Available at: www.cfsan.fda.gov/~dms/hclm-k.html.
  3. Kurowska EM, Spence JD, Jordan J, et al. HDL-cholesterol-raising effect of orange juice in subjects with hypercholesterolemia. Am J Clin Nutr 2000;72:1095-100. PubMed
  4. Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
  5. Bailey DG, Dresser GK, Munoz C, et al. Reduction of fexofenadine bioavailability by fruit juices. Clin Pharmacol Ther 2001;69:P21.
  6. Pletz MW, Petzold P, Allen A, et al. Effect of calcium carbonate on bioavailability of orally administered gemifloxacin. Antimicrob Agents Chemother 2003;47:2158-60.. PubMed
  7. Lilja JJ, Juntti-Patinen L, Neuvonen PJ. Orange juice substantially reduces the bioavailability of the beta-adrenergic-blocking agent celiprolol. Clin Pharmacol Ther 2004;75:184-90.
  8. Tian R, Koyabu N, Takanaga H, et al. Effects of grapefruit juice and orange juice on the intestinal efflux of P-glycoprotein substrates. Pharm Res 2002;19:802-9. PubMed
  9. Vanapalli SR, Chen Y, Ellingrod VL, et al. Orange juice decreases the oral bioavailability of ivermectin in health volunteers. Clin Pharmacol Ther 2003;73 (Abstract PDII-A-10):P94.
  10. Huang SM, Lesko LJ. Drug-drug, drug-dietary supplement, and drug-citrus fruit and other food interactions: what have we learned? J Clin Pharmacol 2004;44:559-69. PubMed
  11. Koitabashi Y, Kumai T, Matsumoto N, et al. Orange juice increased the bioavailability of pravastatin, 3-hydroxy-3-methylglutaryl CoA reductase inhibitor, in rats and healthy human subjects. Life Sci 2006;78:2852-9. PubMed
  12. Takanaga H, Ohnishi A, Yamada S, et al. Polymethoxylated flavones in orange juice are inhibitors of P-glycoprotein but not cytochrome P450 3A4. J Pharmacol Exp Ther 2000;293:230-6. DOI
  13. Greenblatt DJ. Analysis of drug interactions involving fruit beverages and organic anion-transporting polypeptides. J Clin Pharmacol 2009;49:1403-7. PubMed
  14. Bailey DG. Fruit juice inhibition of uptake transport: a new type of food-drug interaction. Br J Clin Pharmacol 2010;70:645-55. PubMed
  15. Kamath AV, Yao M, Zhang Y, Chong S. Effect of fruit juices on the oral bioavailability of fexofenadine in rats. J Pharm Sci 2005;94:233-9. PubMed
  16. Kays MB, Overholser BR, Mueller BA, et al. Effects of sevelamer hydrochloride and calcium acetate on the oral bioavailability of ciprofloxacin. Am J Kidney Dis. 2003;42(6):1253-9. PubMed
  17. Neuhofel, A. L., Wilton, J. H., Victory, J. M., Hejmanowsk, L. G., and Amsden, G. W. Lack of bioequivalence of ciprofloxacin when administered with calcium-fortified orange juice: a new twist on an old interaction. J Clin Pharmacol. 2002;42(4):461-466. DOI

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Cassia Cinnamon 20 references
  1. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  2. Khan A, Safdar M, Ali Khan M, et al. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care 2003;26:3215-8. PubMed
  3. De Benito V, Alzaga R. Occupational allergic contact dermatitis from cassia (Chinese cinnamon) as a flavouring agent in coffee. Contact Dermatitis 1999;40:165. PubMed
  4. Drake TE, Maibach HI. Allergic contact dermatitis and stomatitis caused by a cinnamic aldehyde-flavored toothpaste. Arch Dermatol 1976;112:202-3.
  5. Press release. Cinnamon capsules to reduce blood sugar are medicinal products! Efficacy has not been scientifically proven - some products contain high levels of coumarin. Federal Institute of Risk Assessment (BfM), Germany, November 11, 2006. Available a
  6. Felter SP, Vassallo JD, Carlton BD, Daston GP. A safety assessment of coumarin taking into account species-specificity of toxicokinetics. Food Chem Toxicol 2006;44:462-75. PubMed
  7. Crawford P. Effectiveness of cinnamon for lowering hemoglobin A1C in patients with type 2 diabetes: a randomized, controlled trial. J Am Board Fam Med 2009;22:507-12. PubMed
  8. Akilen, R., Tsiami, A., Devendra, D., and Robinson, N. Glycated haemoglobin and blood pressure-lowering effect of cinnamon in multi-ethnic Type 2 diabetic patients in the UK: a randomized, placebo-controlled, double-blind clinical trial. Diabet.Med. 2010; PubMed
  9. Lu T, Sheng H Wu J Cheng Y Zhu J Chen Y. Cinnamon extract improves fasting blood glucose and glycosylated hemoglobin level in Chinese patients with type 2 diabetes. Nutr Res. 2012;32(6):408-412. PubMed
  10. Choi, J., Lee, K. T., Ka, H., Jung, W. T., Jung, H. J., and Park, H. J. Constituents of the essential oil of the Cinnamomum cassia stem bark and the biological properties. Arch Pharm Res 2001;24(5):418-423.
  11. Altschuler JA, Casella SJ, MacKenzie TA, Curtis KM. The effect of cinnamon on A1C among adolescents with type 1 diabetes. Diabetes Care 2007;30(4):813-6. PubMed
  12. Stoecker BR, Zhan Z, Luo R, et al. Cinnamon extract lowers blood glucose in hyperglycemic subjects. FASEB J. 2010;22:722.1 (Abstract only). DOI
  13. Admani S, Hill H, Jacob SE. Cinnamon Sugar Scrub Dermatitis: "Natural" Is Not Always Best. Pediatr Dermatol. 2017;34(1):e42-e43. PubMed
  14. Isaac-Renton M, Li MK, Parsons LM. Cinnamon spice and everything not nice: many features of intraoral allergy to cinnamic aldehyde. Dermatitis. 2015;26(3):116-21. PubMed
  15. Vandersall A, Katta R. Eyelid dermatitis as a manifestation of systemic contact dermatitis to cinnamon. Dermatitis. 2015 Jul-Aug;26(4):189. PubMed
  16. Wickenberg J, Lindstedt S, Nilsson J, Hlebowicz J. Cassia cinnamon does not change the insulin sensitivity or the liver enzymes in subjects with impaired glucose tolerance. Nutr J 2014 Sep 24;13:96. PubMed
  17. Brancheau D, Patel B, Zughaib M. Do cinnamon supplements cause acute hepatitis? Am J Case Rep 2015;16:250-4. PubMed
  18. Shekarchizadeh-Esfahani P, Heydarpour F, Izadi F, Jalili C. The effect of cinnamon supplementation on liver enzymes in adults: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med 2021;58:102699. PubMed
  19. Bernaola J, Valverde-Monge M, Otal-Buesa M, Cullen D, Heras-Mendaza F. Cinnamon allergic contact cheilitis. Contact Dermatitis 2023;88(5):418-419. PubMed
  20. Patel K, Howard M, Tate B. Cheilitis caused by allergic contact dermatitis to cinnamon in chai tea: A case report. Contact Dermatitis 2023;88(3):239-240. PubMed

See these in context on the Cassia Cinnamon monograph →

Rosemary 20 references
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.
  3. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  4. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  5. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  6. Cartier LC, Lehrer A, Malo JL. Occupational asthma caused by aromatic herbs. Allergy 1996;51:647-9. DOI
  7. Burkhard PR, Burkhardt K, Haenggeli CA, Landis T. Plant-induced seizures: reappearance of an old problem. J Neurol 1999;246:667-70. PubMed
  8. Swain AR, Dutton SP, Truswell AS. Salicylates in foods. J Am Diet.Assoc 1985;85(8):950-60. DOI
  9. Zhu BT, Loder DP, Cai MX, et al. Dietary administration of an extract from rosemary leaves enhances the liver microsomal metabolism of endogenous estrogens and decreases their uterotropic action in CD-1 mice. Carcinogenesis 1998;19(10):1821-7. PubMed
  10. Debersac P, Heydel JM, Amiot MJ, et al. Induction of cytochrome P450 and/or detoxication enzymes by various extracts of rosemary: description of specific patterns. Food Chem Toxicol 2001;39(9):907-18. PubMed
  11. Debersac P, Vernevaut MF, Amiot MJ, et al. Effects of a water-soluble extract of rosemary and its purified component rosmarinic acid on xenobiotic-metabolizing enzymes in rat liver. Food Chem Toxicol 2001;39(2):109-17. PubMed
  12. Lee JJ, Jin YR, Lee JH, et al. Antiplatelet activity of carnosic acid, a phenolic diterpene from Rosmarinus officinalis. Planta Med 2007;73(2):121-7.
  13. Yamamoto J, Yamada K, Naemura A, et al. Testing various herbs for antithrombotic effect. Nutrition 2005;21(5):580-7. PubMed
  14. Naemura A, Ura M, Yamashita T, et al. Long-term intake of rosemary and common thyme herbs inhibits experimental thrombosis without prolongation of bleeding time. Thromb Res 2008;122(4):517-22. PubMed
  15. Lee JJ, Jin YR, Lim Y, et al. Antiplatelet activity of carnosol is mediated by the inhibition of TXA2 receptor and cytosolic calcium mobilization. Vascul Pharmacol 2006;45:148-53. PubMed
  16. Bakirel, T., Bakirel, U., Keles, O. U., Ulgen, S. G., and Yardibi, H. In vivo assessment of antidiabetic and antioxidant activities of rosemary (Rosmarinus officinalis) in alloxan-diabetic rabbits. J Ethnopharmacol 2-28-2008;116(1):64-73. PubMed
  17. Erenmemisoglu, A., Saraymen, R., and Ustun, S. Effect of a Rosmarinus officinalis leave extract on plasma glucose levels in normoglycaemic and diabetic mice. Pharmazie 1997;52(8):645-646.
  18. Valones MAA, Silva ICG, Gueiros LAM, Leão JC, Caldas AF Jr, Carvalho AAT. Clinical assessment of rosemary-based toothpaste (Rosmarinus officinalis Linn.): A randomized controlled double-blind study. Braz Dent J. 2019;30(2):146-151. PubMed
  19. Quirarte-Báez SM, Zamora-Perez AL, Reyes-Estrada CA, et al. A shortened treatment with rosemary tea (rosmarinus officinalis) instead of glucose in patients with diabetes mellitus type 2 (TSD). J Popul Ther Clin Pharmacol. 2019;26(4):e18-e28.
  20. Al Jamal A. Effect of rosemary (Rosmarinus officinalis) on lipid profiles and blood glucose in human diabetic patients (type-2). African J. Biochem. Res. 2014;8(8):147-50. DOI

See these in context on the Rosemary monograph →

Clove 26 references
  1. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
  3. Kanerva L, Estlander T, Jolanki R. Occupational allergic contact dermatitis from spices. Contact Dermatitis 1996;35:157-62. PubMed
  4. Chen SJ, Wang MH, Chen IJ. Antiplatelet and calcium inhibitory properties of eugenol and sodium eugenol acetate. Gen Pharmacol 1996;27:629-33. PubMed
  5. Malson JL, Lee EM, Murty R, et al. Clove cigarette smoking: biochemical, physiological, and subjective effects. Pharmacol Biochem Behav 2003;74:739-45. PubMed
  6. Kirsch CM, Yenokida GG, Jensen WA, et al. Non-cardiogenic pulmonary oedema due to the intravenous administration of clove oil. Thorax 1990;45:235-6. PubMed
  7. Pallares, D. E. Link between clove cigarettes and urticaria? Postgrad.Med 10-1-1999;106(4):153. PubMed
  8. Barnard, D. R. Repellency of essential oils to mosquitoes (Diptera: Culicidae). J Med Entomol. 1999;36(5):625-629. PubMed
  9. Sanchez-Perez, J. and Garcia-Diez, A. Occupational allergic contact dermatitis from eugenol, oil of cinnamon and oil of cloves in a physiotherapist. Contact Dermatitis 1999;41(6):346-347. PubMed
  10. Andersen, K. E., Johansen, J. D., Bruze, M., Frosch, P. J., Goossens, A., Lepoittevin, J. P., Rastogi, S., White, I., and Menne, T. The time-dose-response relationship for elicitation of contact dermatitis in isoeugenol allergic individuals. Toxicol.Appl PubMed
  11. Alqareer, A., Alyahya, A., and Andersson, L. The effect of clove and benzocaine versus placebo as topical anesthetics. J Dent 2006;34(10):747-750. PubMed
  12. Lane, B. W., Ellenhorn, M. J., Hulbert, T. V., and McCarron, M. Clove oil ingestion in an infant. Hum.Exp Toxicol. 1991;10(4):291-294. PubMed
  13. Quirce, S., Fernandez-Nieto, M., del, Pozo, V, Sastre, B., and Sastre, J. Occupational asthma and rhinitis caused by eugenol in a hairdresser. Allergy 2008;63(1):137-138. PubMed
  14. Srivastava, K. C. and Malhotra, N. Acetyl eugenol, a component of oil of cloves (Syzygium aromaticum L.) inhibits aggregation and alters arachidonic acid metabolism in human blood platelets. Prostaglandins Leukot.Essent.Fatty Acids 1991;42(1):73-81. PubMed
  15. Dyrbye, B. A., Dubois, L., Vink, R., and Horn, J. A patient with clove oil intoxication. Anaesth.Intensive Care 2012;40(2):365-366.
  16. Guidotti, T. L., Laing, L., and Prakash, U. B. Clove cigarettes. The basis for concern regarding health effects. West J Med 1989;151(2):220-228.
  17. Anonymous. Evaluation of the health hazard of clove cigarettes. Council on Scientific Affairs. JAMA 12-23-1988;260(24):3641-3644. DOI
  18. Romaguera, C., Alomar, A., Camarasa, J. M., Garcia, Bravo B., Garcia, Perez A., Grimalt, F., Guerra, P., Lopez, Gorretcher B., Pascual, A. M., Miranda, A., and . Contact dermatitis in children. Contact Dermatitis 1985;12(5):283-284. PubMed
  19. Hackett, P. H., Rodriguez, G., and Roach, R. C. Clove cigarettes and high-altitude pulmonary edema. JAMA 6-28-1985;253(24):3551-3552. DOI
  20. Isaacs, G. Permanent local anaesthesia and anhidrosis after clove oil spillage. Lancet 4-16-1983;1(8329):882. PubMed
  21. Saeed, S. A. and Gilani, A. H. Antithrombotic activity of clove oil. J Pak Med Assoc 1994;44(5):112-115.
  22. Hartnoll, G., Moore, D., and Douek, D. Near fatal ingestion of oil of cloves. Arch.Dis Child 1993;69(3):392-393. PubMed
  23. Srivastava, K. C. Antiplatelet principles from a food spice clove (Syzygium aromaticum L) [corrected]. Prostaglandins Leukot.Essent.Fatty Acids 1993;48(5):363-372.
  24. Jiang Q, Wu Y, Zhang H, et al. Development of essential oils as skin permeation enhancers: penetration enhancement effect and mechanism of action. Pharmaceutical Biol. 2017;55(1):1592-1600. PubMed
  25. Mohan R, Jose S, Mulakkal J, Karpinsky-Semper D, Swick AG, Krishnakumar IM. Water-soluble polyphenol-rich clove extract lowers pre- and post-prandial blood glucose levels in healthy and prediabetic volunteers: an open label pilot study. BMC Complement Alt PubMed
  26. Alharbi NFM, Ahad A, Bin Jardan YA, Al-Jenoobi FI. Effect of eugenol on cytochrome P450 1A2, 2C9, 2D6, and 3A4 activity in human liver microsomes. Saudi Pharm J 2024;32(7):102118. PubMed

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Oregano 12 references
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. Benito M, Jorro G, Morales C, et al. Labiatae allergy: systemic reactions due to ingestion of oregano and thyme. Ann Allergy Asthma Immunol 1996;76:416-8. PubMed
  3. Chevallier A. Encyclopedia of Herbal Medicine. 2nd ed. New York, NY: DK Publ, Inc., 2000.
  4. Ciganda C, and Laborde A. Herbal infusions used for induced abortion. J Toxicol.Clin Toxicol. 2003;41:235-239. PubMed
  5. Futrell, J. M. and Rietschel, R. L. Spice allergy evaluated by results of patch tests. Cutis 1993;52(5):288-290.
  6. Tognolini, M., Barocelli, E., Ballabeni, V., Bruni, R., Bianchi, A., Chiavarini, M., and Impicciatore, M. Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity. Life Sci. 2-23-2006;78(13):1419-1432. PubMed
  7. Goun, E., Cunningham, G., Solodnikov, S., Krasnykch, O., and Miles, H. Antithrombin activity of some constituents from Origanum vulgare. Fitoterapia 2002;73(7-8):692-694. PubMed
  8. Lemhadri, A., Zeggwagh, N. A., Maghrani, M., Jouad, H., and Eddouks, M. Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. J Ethnopharmacol. 2004;92(2-3):251-256. PubMed
  9. McCue, P., Vattem, D., and Shetty, K. Inhibitory effect of clonal oregano extracts against porcine pancreatic amylase in vitro. Asia Pac.J Clin.Nutr. 2004;13(4):401-408.
  10. Ragi, J., Pappert, A., Rao, B., Havkin-Frenkel, D., and Milgraum, S. Oregano extract ointment for wound healing: a randomized, double-blind, petrolatum-controlled study evaluating efficacy. J.Drugs Dermatol. 2011;10(10):1168-1172.
  11. Singletary K. Oregano: overview of the literature on health benefits. Nutrition Today 2010;45(3):129-38.
  12. Silva MLAE, Lucarini R, Dos Santos FF, et al. Hypoglycemic effect of rosmarinic acid-rich infusion (RosCE) from Origanum vulgare in alloxan-induced diabetic rats. Nat Prod Res 2022;36(17):4525-4531.

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Black Pepper 29 references
  1. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  3. Bano G, Amla V, Raina RK, et al. The effect of piperine on pharmacokinetics of phenytoin in healthy volunteers. Planta Med 1987;53:568-9. PubMed
  4. Bano G, et al. Effect of piperine on bioavailability and pharmacokinetics of propranolol and theophylline in healthy volunteers. Eur J Clin Pharmacol 1991;41;615-7. PubMed
  5. Cohle SD, Trestrail JD III, Graham MA, et al. Fatal pepper aspiration. Am J Dis Child 1988;142:633-6. PubMed
  6. Bhardwaj RK, Glaeser H, Becquemont L, et al. Piperine, a major constituent of black pepper, inhibits human P-glycoprotein and CYP3A4. J Pharmacol Exp Ther 2002;302:645-50. PubMed
  7. Velpandian T, Jasuja R, Bhardwaj RK, et al. Piperine in food: interference in the pharmacokinetics of phenytoin. Eur J Drug Metab Pharmacokinet 2001;26:241-7. PubMed
  8. Pattanaik S, Hota D, Prabhakar S, et al. Pharmacokinetic interaction of a single dose of piperine with steady-state carbamazepine in epilepsy patients. Phytother Res 2009;23:1281-6.
  9. Munakata, M., Kobayashi, K., Niisato-Nezu, J., Tanaka, S., Kakisaka, Y., Ebihara, T., Ebihara, S., Haginoya, K., Tsuchiya, S., and Onuma, A. Olfactory stimulation using black pepper oil facilitates oral feeding in pediatric patients receiving long-term en
  10. Myers, B. M., Smith, J. L., and Graham, D. Y. Effect of red pepper and black pepper on the stomach. Am J Gastroenterol 1987;82(3):211-214.
  11. Raghavendra, R. H. and Naidu, K. A. Spice active principles as the inhibitors of human platelet aggregation and thromboxane biosynthesis. Prostaglandins Leukot.Essent.Fatty Acids 2009;81(1):73-78. PubMed
  12. Subehan, Usia, T., Kadota, S., and Tezuka, Y. Mechanism-based inhibition of human liver microsomal cytochrome P450 2D6 (CYP2D6) by alkamides of Piper nigrum. Planta Med 2006;72(6):527-532.
  13. Kasibhatta, R. and Naidu, M. U. Influence of piperine on the pharmacokinetics of nevirapine under fasting conditions: a randomised, crossover, placebo-controlled study. Drugs R.D. 2007;8(6):383-391. PubMed
  14. Usia, T., Iwata, H., Hiratsuka, A., Watabe, T., Kadota, S., and Tezuka, Y. CYP3A4 and CYP2D6 inhibitory activities of Indonesian medicinal plants. Phytomedicine. 2006;13(1-2):67-73. PubMed
  15. Mujumdar, A. M., Dhuley, J. N., Deshmukh, V. K., Raman, P. H., Thorat, S. L., and Naik, S. R. Effect of piperine on pentobarbitone induced hypnosis in rats. Indian J Exp.Biol. 1990;28(5):486-487.
  16. Panda, S. and Kar, A. Piperine lowers the serum concentrations of thyroid hormones, glucose and hepatic 5'D activity in adult male mice. Horm.Metab Res. 2003;35(9):523-526. PubMed
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  19. Han, Y., Chin Tan, T. M., and Lim, L. Y. In vitro and in vivo evaluation of the effects of piperine on P-gp function and expression. Toxicol.Appl.Pharmacol. 8-1-2008;230(3):283-289. PubMed
  20. Sharma, P., Varma, M. V., Chawla, H. P., and Panchagnula, R. In situ and in vivo efficacy of peroral absorption enhancers in rats and correlation to in vitro mechanistic studies. Farmaco 2005;60(11-12):874-883. PubMed
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  23. Marotta, R. B. and Floch, M. H. Diet and nutrition in ulcer disease. Med Clin North Am 1991;75(4):967-979. PubMed
  24. Subehan, Usia, T., Iwata, H., Kadota, S., and Tezuka, Y. Mechanism-based inhibition of CYP3A4 and CYP2D6 by Indonesian medicinal plants. J Ethnopharmacol. 5-24-2006;105(3):449-455. PubMed
  25. Gimenez L, Zacharisen M. Severe pepper allergy in a young child. WMJ. 2011 Jun;110(3):138-9.
  26. Ren T, Yang M, Xiao M, Zhu J, Xie W, Zuo Z. Time-dependent inhibition of carbamazepine metabolism by piperine in anti-epileptic treatment. Life Sci. 2019;218:314-323. PubMed
  27. Thomas AB, Choudhary DC, Raje A, Nagrik SS. Pharmacokinetics and pharmacodynamic herb-drug interaction of piperine with atorvastatin in rats. J Chromatogr Sci 2021;59(4):371-80. PubMed
  28. Haron MH, Dale O, Martin K, et al. Evaluation of the Herb-Drug Interaction Potential of Commonly Used Botanicals on the US Market with Regard to PXR- and AhR-Mediated Influences on CYP3A4 and CYP1A2. J Diet Suppl 2022. PubMed
  29. Lin F, Hu Y, Zhang Y, Zhao L, Zhong D, Liu J. Predicting Food-Drug Interactions between Piperine and CYP3A4 Substrate Drugs Using PBPK Modeling. Int J Mol Sci 2024;25(20):10955. PubMed

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Eucalyptus 23 references
  1. Electronic Code of Federal Regulations. Title 21. Part 182 -- Substances Generally Recognized As Safe. Available at: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=182
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  12. Jori, A., Bianchetti, A., Prestini, P. E., and Gerattini, S. Effect of eucalyptol (1,8-cineole) on the metabolism of other drugs in rats and in man. Eur.J Pharmacol 1970;9(3):362-366. PubMed
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  16. Higgins C, Palmer A, Nixon R. Eucalyptus oil: contact allergy and safety. Contact Dermatitis. 2015;72(5):344-346. PubMed
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  19. Paulsen E, Thormann H, Vestergaard L. Eucalyptus species as a cause of airborne allergic contact dermatitis. Contact Dermatitis. 2018;78(4):301-303.
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See these in context on the Eucalyptus monograph →

Lemon Balm 12 references
  1. Wolbling RH, Leonhardt K. Local therapy of herpes simplex with dried extract from Melissa officinalis. Phytomedicine 1994;1:25-31.
  2. Akhondzadeh S, Noroozian M, Mohammadi M, et al. Melissa officinalis extract in the treatment of patients with mild to moderate Alzheimer's disease: a double blind, randomised, placebo controlled trial. J Neurol Neurosurg Psychiatry 2003;74:863-6. PubMed
  3. Kennedy DO, Scholey AB, Tildesley NT, et al. Modulation of mood and cognitive performance following acute administration of Melissa officinalis (lemon balm). Pharmacol Biochem Behav 2002;72:953-64. PubMed
  4. Albrecht M, Berger W, Laux P, Schmidt U, et al. Psychopharmaka und Verkehrssicherheit. Der Einfluß von Euvegal® - Dragees forte auf die Fahrtüchtigkeit und Kombinationswirkungen mit Alkohol Z Allg Med 1995;71:1215-25.
  5. Herberg, KW. Nebenwirkungen pflanzlicher Beruhigungsmittel/ Leistung und Befinden nach Einnahme einer Baldrian-Hopfen-Kombination. Z.Allg Med 1996;72:234-240.
  6. Soulimani R, Fleurentin J, Mortier F, et al. Neurotropic action of the hydroalcoholic extract of Melissa officinalis in the mouse. Planta Med. 1991 Apr;57:105-9.
  7. Sourgens H, Winterhoff H, Gumbinger HG, et al. Antihormonal effects of plant extracts. TSH- and prolactin-suppressing properties of Lithospermum officinale and other plants. Planta Med. 1982 Jun;45:78-86. DOI
  8. Auf'mkolk M, Ingbar JC, Amir SM, et al. Inhibition by certain plant extracts of the binding and adenylate cyclase stimulatory effect of bovine thyrotropin in human thyroid membranes. Endocrinology. 1984 Aug;115:527-34. PubMed
  9. Santini F, Vitti P, Ceccarini G, et al. In vitro assay of thyroid disruptors affecting TSH-stimulated adenylate cyclase activity. J Endocrinol Invest. 2003 Oct;26:950-5. PubMed
  10. Alijaniha F, et al. Heart palpitation relief with Melissa officinalis leaf extract: double blind, randomized, placebo controlled trial of efficacy and safety. J Ethnopharmacol. 2015;164:378-384. doi: 10.1016/j.jep.2015.02.007. Epub 2015 Feb 11. PubMed
  11. Araj-Khodaei M, Noorbala AA, Yarani R, et al. A double-blind, randomized pilot study for comparison of Melissa officinalis L. and Lavandula angustifolia Mill. with Fluoxetine for the treatment of depression. BMC Complement Med Ther. 2020;20(1):207. PubMed
  12. Kucuk U, Pham M, Raza Raja MH, Saad Shaukat MH, Clark R. Transient complete atrioventricular block associated with herbal supplement use. S D Med 2023;76(7):311-313.

See these in context on the Lemon Balm monograph →

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DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

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