Drug & supplement interaction

Oregano + Cephalexin

Cephalexin brand names: Keflex, Keftab, Cephalex, Lexin.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Oregano and Cephalexin in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Oregano and Cephalexin

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Cephalexin and Oregano in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Oregano safety at a glance

Oregano overall Use caution Safe as a food, but concentrated oregano oil supplements are stronger and less studied.
Pregnancy Possibly Unsafe When used orally in medicinal amounts. Oregano is thought to have abortifacient and emmenagogue effects. Read the full pregnancy detail
Breastfeeding Use caution Stick to normal food amounts; safety of supplements while breastfeeding is not established.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Pharmacist analysis

Oregano (and oregano oil) supplements are generally considered safe and there is no indication that there is an interaction between the drug highlighted in this interaction monograph and oregano.

However, as with all supplements, it is important to talk to your doctor before starting anything new, so you can be appropriately monitored.

In terms of drug interactions that have been reported with oregano, below are some examples.

Anticoagulant; Antiplatelet Drugs

Anticoagulants and antiplatelet drugs work by slowing down or preventing blood clotting. While they are essential medications for individuals with certain conditions, they come with an increased risk of bleeding.

Some studies have reported that oregano oil may also increase the risk of bleeding, as it contains compounds that have antithrombin activity and can inhibit platelet aggregation.

Therefore, taking oregano oil along with anticoagulants or antiplatelet drugs may increase the risk of bleeding, bruising, and other adverse effects.

Anti-Diabetic Drugs

Several studies suggest that oregano supplements may help lower blood glucose (i.e., sugar) levels. In vitro and animal research has shown that oregano extracts might stimulate glucose uptake and reduce blood glucose levels.

Therefore, based on the available evidence, combining oregano oil with antidiabetic drugs could potentially cause blood sugar levels to drop too low, leading to hypoglycemia.

However, it is important to note that studies reporting that oregano can reduce blood glucose levels have not reported it causing hypoglycemia.

References

  • Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region. PubMed
  • Inhibitory effect of clonal oregano extracts against porcine pancreatic amylase in vitro. PubMed
  • Antithrombin activity of some constituents from Origanum vulgare. PubMed
  • Comparative screening of plant essential oils: phenylpropanoid moiety as basic core for antiplatelet activity. PubMed

Safe With Keflex (Cephalexin)?

There is no known interaction between cephalexin and oregano (or oregano oil).

While oregano oil is purported to have antimicrobial effects, it is not known to interact with antibiotics, like cephalexin, in any way. They should not affect one another.

—

Still wondering about combining Cephalexin and Oregano? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Cephalexin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Cephalexin is filed under 7 classifications — including organic anion transporter 3 (oat3) substrates, organic anion transporter 1 (oat1) substrates, antibiotic drugs. Oregano has documented interactions with 2 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate) and antidiabetes drugs (moderate) — and none of Cephalexin’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Oregano Does Interact With Other Medications

Oregano has 208 moderate known drug interactions in our database — Cephalexin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 208 No known interaction 2,622 (incl. Cephalexin)
Taking anything else?

Check Another of Your Medications Against Oregano

Covers the 2,830 medications we’ve checked against Oregano. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Oregano and Cephalexin May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • An allergic reaction Worth acting on Additional detail

    Oregano

    “Systemic allergic reactions have been reported with oregano. A 45-year-old male developed pruritus, respiratory difficulty, hypotension, swelling of the lips and tongue, and facial edema after ingesting pizza seasoned with oregano. He had 2 similar episodes after ingesting foods seasoned with thyme, another member of the Lamiaceae family.”

    Oregano · Natural Medicines adverse-effect record, reported in hypotension.

    1 source cited
    1. 3705. 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

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Stomach upset Additional detail

    Oregano

    Recorded for Oregano in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

  • Itching Additional detail

    Oregano

    Recorded for Oregano in the same Natural Medicines adverse-effect record shown under An allergic reaction above.

    Cephalexin

    Listed in the ADVERSE REACTIONS section of the FDA label for Cephalexin. Read the label on DailyMed ›

Reported for Oregano but not commonly for Cephalexin: low blood pressure, a severe allergic reaction, a skin rash and swelling.

Effects for Cephalexin come from the ADVERSE REACTIONS section of its FDA label; effects for Oregano come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Oregano in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally in medicinal amounts. Oregano is thought to have abortifacient and emmenagogue effects.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Oregano or Cephalexin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Oregano or Cephalexin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Cephalexin

This page covers Oregano only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Cephalexin page lists 61 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Siberian Cocklebur (major), African Wild Potato (moderate) and Aristolochia (moderate).

By severity: 3 major · 47 moderate · 11 minor.

From our pharmacist’s overview on the Cephalexin page

“Cephalexin (Keflex) is one of the most commonly prescribed oral antibiotics, usually for skin and urinary infections, and its supplement list warrants genuine care rather than a quick skim. Three of the 61 ingredients on file rate major.”

Reviewed by 2 · Jul 18, 2026

Open the Cephalexin interaction page

One more smart check

Taking Oregano as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,632 real supplement products containing Oregano, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Oregano. Even though Oregano itself has no known interaction with Cephalexin, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Oregano and Cephalexin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Oregano
Top 10%

#133 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Cephalexin
Top 5%

#65 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Oregano reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Oregano and Cephalexin records this page draws on were last updated July 11, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Oregano

What is Oregano?

Oregano
  • Digestive upset
  • Respiratory and cold symptoms
  • Antimicrobial support
  • Intestinal parasites
  • Skin and fungal concerns

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 have antimicrobial and antioxidant properties, strong human evidence for treating any specific health condition is limited. Used as a food, oregano is very safe; concentrated oregano oil supplements should be used cautiously and discussed with your pharmacist or doctor.

Origanum vulgare · Lamiaceae · Leaves and essential oil · Culinary herb, tea, capsules, softgels, liquid oil (oil of oregano), tinctures

An interaction check asks whether these two react with each other — it does not ask whether Oregano is a good idea for someone in your situation. Here is what our Oregano record says about it on its own.

Oregano: dosing

There is no official, well-established dose for oregano supplements. Products vary widely in strength and in how much carvacrol they contain, so it is hard to compare them.The safest approach is to follow the directions on the product label and not exceed the recommended amount.

From our Oregano monograph — the full record covers uses, side effects and every documented interaction.

Read the full Oregano monograph & all interactions
Medication

About Cephalexin

What Is Cephalexin Used For?

Brand names: Keflex, Keftab, Cephalex, Lexin

Cephalexin treats bacterial infections caused by susceptible strains of bacteria. It is used for respiratory tract infections, ear infections (otitis media), skin and skin structure infections, bone infections, and genitourinary tract infections — including acute prostatitis.

It works only against bacterial infections — not viruses like colds or flu. Your prescriber should use it only when a bacterial infection is confirmed or strongly suspected, to help prevent antibiotic resistance.

Most-Reported Side Effects for Cephalexin

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Chronic kidney disease 2,157 reports
Renal failure 1,558 reports
Acute kidney injury 1,550 reports
Diarrhea 1,405 reports
Fatigue 1,303 reports
See full Cephalexin drug information
Keep checking

Other Drugs & Oregano

Browse every other medication we’ve checked against Oregano — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
208Moderate
0Minor
2,621No known interaction
208 Moderate 2,621 No interaction
Moderate

208 interactions

Showing 60 of 208 moderate interactions — see all 208 on the Oregano page.

No interaction 2,621 drugs checked — show the list

We also checked Oregano against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,621 medications checked with no known interaction — see the full Oregano list.

See the full Oregano interactions page
See every supplement checked against Cephalexin, ranked by severity
Evidence & sources

Oregano References

The 12 references that drive our Oregano monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  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.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Oregano and Cephalexin Together: Common Questions

Is it safe to take Oregano with Cephalexin?
We do not list a known interaction between Oregano and Cephalexin. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Oregano and Cephalexin have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Oregano and Cephalexin combination checked?
Interactions in our licensed database are recorded against drug classes. Cephalexin is filed under 7 classifications, and Oregano has documented interactions with 2 drug classes — none of Cephalexin's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Oregano interact with any other medications?
Yes. Oregano has 208 documented drug interactions in our database — Cephalexin is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Cephalexin interact with any supplements?
Yes. Cephalexin has documented interactions with 61 supplements in our database — Oregano is not one of them. The Cephalexin interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Oregano monograph Uses, safety profile, and every drug interaction in one place Cephalexin drug information The full plain-English guide to this medication Cephalexin supplement interactions Every supplement checked against Cephalexin, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Cephalexin and Oregano?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.