Interactions on record — worth a quick check against your medications. Based on 2 of 3 ingredients. Check your meds →
Dietary supplement

Tri-Metabolic Control Ingredients & Drug Interactions

by Douglas Laboratories

Tri-Metabolic Control label
See full label image
Capsule Category: Other Combinations
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Tri-Metabolic Control 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: Moderate

Tri-Metabolic Control is a dietary supplement by Douglas Laboratories with 3 active ingredients. Its ingredients are commonly taken for memory and cognitive support, nerve pain (neuropathy), energy and fatigue.Based on those ingredients, 1,077 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Piper betle (leaf) extract, Acetyl-L-Carnitine. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against Tri-Metabolic Control by Douglas Laboratories

Ask about any prescription or over-the-counter medication and we check it for interactions with Tri-Metabolic Control by Douglas Laboratories — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of Tri-Metabolic Control by Douglas Laboratories

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Jul 11, 2026

What’s inside

Low disclosure
Ingredient Transparency · database check
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 1 of its 3 active ingredients.
  • “LOWAT Proprietary Blend” is a proprietary blend — the label gives one combined amount (300 mg) without saying how much of each component you get.

This product contains 3 active ingredients. Acetyl-L-carnitine is an amino acid that plays a role in energy production in cells.

The other two — Dolichos biflorus seed extract and Piper betle leaf extract — are herbal ingredients. The capsule also contains inactive ingredients: hydroxypropyl methylcellulose, microcrystalline cellulose, ascorbyl palmitate, and silica.

Does it work?

Moderate evidence
Evidence for Intended Use · database check
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

This product doesn't appear to be marketed for a specific use, so we graded its ingredients' overall clinical evidence instead.

Moderate

Some clinical evidence supports its ingredients for:

Why this rating?
  • We looked at the product name, claims, and label statements and couldn't find a stated purpose to grade.
  • Since the label doesn't commit to one use, we graded the ingredients' overall clinical evidence instead.
  • On file: Age-related cognitive decline — rated "Possibly Effective" (Acetyl-l-carnitine) (Natural Medicines).
  • On file: Alcohol use disorder — rated "Possibly Effective" (Acetyl-l-carnitine) (Natural Medicines).
  • On file: Alzheimer disease — rated "Possibly Effective" (Acetyl-l-carnitine) (Natural Medicines).
  • On file: Depression — rated "Possibly Effective" (Acetyl-l-carnitine) (Natural Medicines).
  • On file: Diabetic neuropathy — rated "Possibly Effective" (Acetyl-l-carnitine) (Natural Medicines).

Acetyl-L-carnitine in this product is rated possibly effective for age-related cognitive decline, Alzheimer disease, alcohol use disorder, diabetic nerve pain, and depression — meaning there's some evidence, but it's not definitive. We hold no effectiveness data on the herbal extracts in this product.

The evidence, ingredient by ingredient Acetyl-l-carnitine Black Pepper

How safe is it?

Well-documented data
Safety Information · database check
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 2 of the 2 matched ingredients.
  • Pregnancy & breastfeeding safety ratings cover 2 of 2.
  • General safety write-ups exist for 2 of 2.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

Acetyl-L-carnitine is generally well tolerated over short-term use, but its long-term safety isn't fully established. Common side effects include agitation, dry mouth, headache, insomnia, and reduced appetite.

A few people report a fishy odor to their urine, breath, or sweat. Nausea, vomiting, diarrhea, and stomach upset are possible but don't occur more often than with placebo.

In people with Alzheimer disease, there are rare reports of mood changes and confusion, though it's unclear whether acetyl-L-carnitine causes them or the disease does. During breastfeeding, the safety of acetyl-L-carnitine is unknown, and avoiding it is the safer choice.

For pregnancy, there is not enough reliable safety information, so it's best avoided unless your doctor advises otherwise. We hold no pregnancy or breastfeeding data for the herbal extracts.

Side effects, ingredient by ingredient Acetyl-l-carnitine Black Pepper

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 2 of the 2 matched ingredients can interact with medications — Black Pepper, Acetyl-l-carnitine.
  • The most serious interaction on file is rated Moderate.
  • Some involve high-stakes drug classes: anticoagulant / antiplatelet drugs; immunosuppressants / transplant drugs; diabetes medications; lithium.
  • For scale: 1,078 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.

Before taking this product, check with us if you take serotonergic drugs such as antidepressants (Moderate risk of serotonin syndrome), blood thinners like warfarin or acenocoumarol (Moderate risk of increased bleeding), or thyroid hormone replacement (Moderate risk of reduced effectiveness). No interactions are documented for the herbal extracts we could check.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFormula with limited ingredient disclosure with some supporting evidence behind its ingredients' uses. Moderate medication interactions have been identified, and safety information is well characterized.

Consider this product if you're interested in acetyl-L-carnitine for cognitive support or energy metabolism and have no blood-thinning or serotonergic medications in your routine. If you take warfarin, other blood thinners, thyroid medication, or antidepressants, talk to your pharmacist before starting.

Breastfeeding parents should avoid it.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 2 of 3 active ingredients matched to our full ingredient reviews (monographs). Based on the product label dated Feb 25, 2021.

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 Tri-Metabolic Control, straight from the product label.

Brand Douglas Laboratories
Barcode (UPC) 310539977569
Net contents 120 Vegetarian Capsule(s)
Market status On market
Date entered into DSLD Feb 25, 2021
DSLD ID 245362
Product type Other Combinations
Supplement form Capsule
Dietary claims / uses All Other, Structure/Function
Intended target group(s) Adult (18 - 50 Years), Gluten Free
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 Tri-Metabolic Control by Douglas Laboratories, 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:
2 Vegetarian Capsule(s)
Maximum serving Sizes:
2 Vegetarian Capsule(s)
Servings per container
60
UPC/BARCODE
310539977569
IngredientAmount% DV
Acetyl-L-Carnitine300 mg--
Dolichos biflorus (seed) extract0 NP--
Piper betle (leaf) extract0 NP--
LOWAT Proprietary Blend300 mg--

Other ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Ascorbyl Palmitate, Silica

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.
Suggested/Recommended/Usage/Directions

Suggested Usage: As a dietary supplement, adults take 2 capsules 30 minutes before a meal, three times daily or as directed by your health professional.

Precautions

Warning: If you are pregnant, nursing, have any health condition or are taking any medication, consult your health professional before using this product.

Keep out of the reach of children.

Use only if safety seal is intact.

Brand IP Statement(s)

LOWAT is a Nutraceuticals trademark

Storage

Store in a cool, dry place.

Formulation

Gluten-free, Non-GMO

Supports metabolic hormones leptin, ghrelin and adiponectin

FDA Disclaimer Statement

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

General Statements

Scan to learn about our manufacturing excellence Contents may not fill bottle in order to accommodate required labeling. Please rely on stated quantity.

FDA Statement of Identity

Dietary Supplement

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

See for yourself

Tri-Metabolic Control by Douglas Laboratories label

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

Tri-Metabolic Control 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 Tri-Metabolic Control by Douglas Laboratories

These are the 3 active ingredients this product is made of. Select any to open its full monograph.

Serving size2 Vegetarian Capsule(s) Dosage formCapsule 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.

Acetyl-L-Carnitine

Interacts with
203 drugs
300 mg per serving Form: Acetyl-L-Carnitine HCl

Acetyl-L-carnitine is a form of the amino acid carnitine that the body uses to help produce energy in cells. It is most studied for nerve pain and mem...

Acetyl-L-Carnitine monograph & interactions

LOWAT Proprietary Blend

300 mg per serving

Other (inactive) ingredients: Hydroxypropyl Methylcellulose, Microcrystalline Cellulose, Ascorbyl Palmitate, Silica. These complete the product’s ingredient list but are not active constituents.

Interaction report

Tri-Metabolic Control by Douglas Laboratories Drug Interactions

Want to check YOUR meds against Tri-Metabolic Control?

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
1,077Drugs
1,036 Moderate 41 Minor

Ingredients driving the most interactions

Piper betle (leaf) extract 1,019
Acetyl-L-Carnitine 203

Individual Drug Interactions

The ingredients in Tri-Metabolic Control interact with 1,077 drugs. Click any drug to see the details.

2 of the 3 ingredients in Tri-Metabolic Control interact with drugs. Each result below shows which ingredient is responsible. Piper betle (leaf) extract Acetyl-L-Carnitine

Each ingredient & the kinds of drugs it affects

For each ingredient in Tri-Metabolic Control 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.

Piper betle (leaf) extract17 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
Piper betle (leaf) extract full monograph & interactions

Acetyl-L-Carnitine4 drug types · 203 drugs

Acenocoumarol (Sintrom)

Theoretically, acetyl-L-carnitine might increase the anticoagulant effects of acenocoumarol.
L-carnitine, the parent compound of acetyl-L-carnitine, might enhance the anticoagulant effects of acenocoumarol, an oral anticoagulant that is similar to warfarin, but shorter-acting. There are at least two case reports of INR elevation when L-carnitine was taken with acenocoumarol. In one case, a 33-year-old male with a previously stable INR had an elevated INR of 4.65 after L-carnitine was started and continued for 10 weeks. INR normalized after discontinuation of the L-carnitine-containing product. It is unclear if such an interaction would also occur with acetyl-L-carnitine.

Likelihood Possible Evidence D
Serotonergic Drugs

Theoretically, acetyl-L-carnitine might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders, when taken with serotonergic drugs.
Animal research shows that acetyl-L-carnitine can increase levels of serotonin in the brain.

Likelihood Possible Evidence D
Thyroid Hormone

Theoretically, acetyl-L-carnitine might decrease the effectiveness of thyroid hormone replacement.
L-carnitine appears to act as a peripheral thyroid hormone antagonist by inhibiting entry of thyroid hormone into the nucleus of cells. Taking L-carnitine also seems to diminish some of the symptoms of hyperthyroidism. It is unclear if such an interaction would occur with acetyl-L-carnitine.

Likelihood Probable Evidence B
Warfarin (Coumadin)

Theoretically, acetyl-L-carnitine might increase the anticoagulant effects of warfarin.
L-carnitine, the parent compound of acetyl-L-carnitine, might increase the anticoagulant effects of acenocoumarol, a shorter-acting oral anticoagulant similar to warfarin. There is not enough information to know whether this interaction occurs with acetyl-L-carnitine and warfarin.

Likelihood Possible Evidence D
Acetyl-L-Carnitine full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Tri-Metabolic Control, from the product label.

Douglas Laboratories

See all Douglas Laboratories products
Name
Douglas Laboratories
Street Address
600 Boyce Road
City
Pittsburgh
State
PA
ZipCode
15205
Phone Number
1.800.245.4440
Web Address
www.douglaslabs.com
Pharmacist Counseling Corner

Tri-Metabolic Control by Douglas Laboratories: Common Questions

Does Tri-Metabolic Control by Douglas Laboratories interact with any medications?
Yes. Based on its ingredients, Tri-Metabolic Control has a known interaction with 1,077 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Tri-Metabolic Control contains 3 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.
What is acetyl-L-carnitine and what does it do in this product?
Acetyl-L-carnitine is an amino acid that helps cells produce energy. It's included here as an active ingredient possibly effective for cognitive decline, Alzheimer disease, diabetic nerve pain, depression, and alcohol use disorder.
What are the most common side effects I might notice?
The most common are agitation, dry mouth, headache, trouble sleeping, and reduced appetite. Some people report nausea, stomach upset, or diarrhea, though these don't occur more often than with placebo. A small number notice a fishy odor to their urine, breath, or sweat.
Is it safe to take if I'm breastfeeding?
No — the safety of acetyl-L-carnitine while breastfeeding is unknown, so avoiding it is the safer choice. Talk with your doctor or pharmacist if you have questions.
What about during pregnancy?
There isn't enough reliable safety information about acetyl-L-carnitine in pregnancy, so it's best avoided unless your doctor advises otherwise. Talk to your doctor or pharmacist for personalized advice.
Does long-term use have any safety concerns?
Acetyl-L-carnitine is generally well tolerated in the short term, but long-term safety hasn't been fully established. It's worth discussing with your pharmacist if you're planning extended use.
What are Dolichos biflorus and Piper betle in this product?
They're herbal extracts included as active ingredients, but we hold no interaction or effectiveness data for them. We can't say what they do or how they interact with medications.

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

Not sure if Tri-Metabolic Control is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

Tri-Metabolic Control label
Go deeper

The Full Monographs Behind Tri-Metabolic Control’s Ingredients

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

Herb & supplement monograph

Acetyl-l-carnitine

Interacts with 203 drugs

Acetyl-L-carnitine is a form of the amino acid carnitine that the body uses to help produce energy in cells. It is most studied for nerve pain and memory-related conditions, though the evide...

Read the full Acetyl-l-carnitine 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 →
Sources

Sources & How We Checked

Tri-Metabolic Control'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 51 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.

Acetyl-l-carnitine 22 references
  1. Thal LJ, Carta A, Clarke WR, et al. A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's Disease. Neurology 1996;47:705-11. PubMed
  2. Sano M, Bell K, Cote L, et al. Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer's Disease. Arch Neurol 1992;49:1137-41. PubMed
  3. Spagnoli A, Lucca U, Menasce G, et al. Long-term acetyl-L-carnitine treatment in Alzheimer's Disease. Neurology 1991;41:1726-32. PubMed
  4. Brooks JO 3rd, Yesavage JA, Carta A, Bravi D. Acetyl L-carnitine slows decline in younger patients with Alzheimer's disease: a reanalysis of a double-blind, placebo-controlled study using the trilinear approach. Int Psychoger 1998;10:193-203. PubMed
  5. Pettegrew JW, Klunk WE, Panchalingam K, et al. Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer's disease. Neurobiol Aging 1995;16:1-4. PubMed
  6. Rai G, Wright G, Scott L, et al. Double-blind, placebo controlled study of acetyl-l-carnitine in patients with Alzheimer's dementia. Curr Med Res Opin 1990;11:638-47. PubMed
  7. Benvenga S, Ruggeri RM, Russo A, et al. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Meta
  8. Montgomery SA, Thal LJ, Amrein R. Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease. Int Clin Psychopharmacol 2003;18:61-71.. PubMed
  9. Martinez E, Domingo P, Roca-Cusachs A. Potentiation of acenocoumarol action by L-carnitine. J Intern Med 1993;233:94.
  10. Hudson S, Tabet N. Acetyl-L-carnitine for dementia. Cochrane Database Syst Rev 2003;2:CD003158.. PubMed
  11. Bachmann HU, Hoffmann A. Interaction of food supplement L-carnitine with oral anticoagulant acenocoumarol. Swiss Med Wkly 2004;134:385. PubMed
  12. De Grandis D, Minardi C. Acetyl-L-carnitine (levacecarnine) in the treatment of diabetic neuropathy. A long-term, randomised, double-blind, placebo-controlled study. Drugs R D 2002;3:223-31. PubMed
  13. 12761 Benvenga S, Amato A, Calvani M, Trimarchi F. Effects of carnitine on thyroid hormone action. Ann N Y Acad Sci 2004;1033:158-67. PubMed
  14. Sima AAF, Calvani M, Mehra M, et al. Acetyl-L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy: An analysis of two randomized, placebo-controlled trials. Diabetes Care 2005;28:89-94.
  15. Youle, M. and Osio, M. A double-blind, parallel-group, placebo-controlled, multicentre study of acetyl L-carnitine in the symptomatic treatment of antiretroviral toxic neuropathy in patients with HIV-1 infection. HIV.Med. 2007;8(4):241-250.
  16. Brennan BP, Jensen JE, Hudson JI, Coit CE, Beaulieu A, Pope HG Jr, Renshaw PF, Cohen BM. A placebo-controlled trial of acetyl-L-carnitine and a-lipoic acid in the treatment of bipolar depression. J Clin Psychopharmacol. 2013 Oct;33(5):627-35.
  17. Ledinek AH, Sajko MC, Rot U. Evaluating the effects of amantadin, modafinil and acetyl-L-carnitine on fatigue in multiple sclerosis--result of a pilot randomized, blind study. Clin Neurol Neurosurg. 2013 Dec;115 Suppl 1:S86-9. PubMed
  18. Martinotti G, Andreoli S, Reina D, Di Nicola M, Ortolani I, Tedeschi D, Fanella F, Pozzi G, Iannoni E, D'Iddio S, Prof LJ. Acetyl-l-Carnitine in the treatment of anhedonia, melancholic and negative symptoms in alcohol dependent subjects. Prog Neuropsychop PubMed
  19. Baek SM, Zheng R, Seo EJ, Hwang DY, Kim BH. Pharmacokinetic comparisons of two acetyl-L-carnitine formulations in healthy Korean volunteers. Int J Clin Pharmacol Ther. 2015;53(11):980-6. PubMed
  20. Goodison G, Overeem K, de Monte V, Siskind D. Mania associated with self-prescribed acetyl-l-carnitine in a man with bipolar I disorder. Australas Psychiatry. 2017;25(1):13-4.
  21. Bruno A, Pandolfo G, Crucitti M, Lorusso S, Zoccali RA, Muscatello MR. Acetyl-L-Carnitine Augmentation of Clozapine in Partial-Responder Schizophrenia: A 12-Week, Open-Label Uncontrolled Preliminary Study. Clin Neuropharmacol. 2016;39(6):277-80. PubMed
  22. Veronese N, Stubbs B, Solmi M, Ajnakina O, Carvalho AF, Maggi S. Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis. Psychosom Med. 2018;80(2):154-9. PubMed

See these in context on the Acetyl-l-carnitine monograph →

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
  17. Lawless, H. and Stevens, D. A. Effects of oral chemical irritation on taste. Physiol Behav. 1984;32(6):995-998. PubMed
  18. Hiwale, A. R., Dhuley, J. N., and Naik, S. R. Effect of co-administration of piperine on pharmacokinetics of beta-lactam antibiotics in rats. Indian J Exp.Biol. 2002;40(3):277-281.
  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
  21. Aher, S., Biradar, S., Gopu, C. L., and Paradkar, A. Novel pepper extract for enhanced P-glycoprotein inhibition. J Pharm.Pharmacol. 2009;61(9):1179-1186. PubMed
  22. Zutshi, R. K., Singh, R., Zutshi, U., Johri, R. K., and Atal, C. K. Influence of piperine on rifampicin blood levels in patients of pulmonary tuberculosis. J Assoc.Physicians India 1985;33(3):223-224.
  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

See these in context on the Black Pepper monograph →

Parts of this content are provided by the Therapeutic Research Center, LLC.

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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team