Drug & supplement interaction

Propionyl-l-carnitine + Tolcapone

Tolcapone brand name: Tasmar.

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 Propionyl-l-carnitine and Tolcapone 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

Propionyl-l-carnitine and Tolcapone

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 Tolcapone and Propionyl-l-carnitine 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.

Propionyl-l-carnitine safety at a glance

Propionyl-l-carnit... overall Use caution Generally well tolerated for short-term use, but talk to a healthcare provider first.
Pregnancy Avoid Safety has not been established, so it is best avoided during pregnancy.
Breastfeeding Avoid Not enough safety data is available, so avoid use while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Tolcapone and Propionyl-l-carnitine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Tolcapone

Interactions in our licensed database are recorded against drug classes, not just single drug names. Tolcapone is filed under 3 classifications — dopamine agonists, hepatotoxic drugs, oral drugs. Propionyl-l-carnitine has documented interactions with 3 drug classes — the most serious being acenocoumarol (sintrom) (moderate), thyroid hormone (moderate) and warfarin (coumadin) (moderate) — and none of Tolcapone’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

Propionyl-l-carnitine Does Interact With Other Medications

Propionyl-l-carnitine has 19 moderate known drug interactions in our database — Tolcapone isn’t one of them. If you take anything else, check it against the full list below.

Moderate 19 No known interaction 2,811 (incl. Tolcapone)
Taking anything else?

Check Another of Your Medications Against Propionyl-l-carnitine

Covers the 2,830 medications we’ve checked against Propionyl-l-carnitine. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Propionyl-l-carnitine and Tolcapone 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.

  • Diarrhea / Vomiting / Nausea Additional detail

    Propionyl-l-carnitine

    “Orally, nausea, vomiting, diarrhea, and gastric pain have been reported with propionyl-L-carnitine use.”

    Propionyl-l-carnitine · Natural Medicines adverse-effect record, reported in diarrhea.

    6 sources cited
    1. 1579. Cherchi A, Lai C, Onnis E, et al. Propionyl carnitine in stable effort angina. Cardiovasc Drugs Ther 1990;4:481-6. PubMed
    2. 1580. Bartels GL, Remme WJ, den Hartog FR, et al. Additional anti-ischemic effects of long-term L-propionylcarnitine in anginal patients treated with conventional antianginal therapy. Cardiovasc Drugs Ther 1995;9:749-53.
    3. 1582. Caponnetto S, Canale C, Masperone MA, et al. Efficacy of L-propionylcarnitine treatment in patients with left ventricular dysfunction. Eur Heart J 1994;15:1267-73. PubMed
    4. 12682. Gentile V, Vicini P, Prigiotti G, et al. Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetes. Curr Med Res Opin 2004;20:1377-84. PubMed
    5. 94439. Brass EP, Koster D, Hiatt WR, Amato A. A systematic review and meta-analysis of propionyl-L-carnitine effects on exercise performance in patients with claudication. Vasc Med 2013;18:3-12.
    6. 94443. Hiatt WR, Creager MA, Amato A, Brass EP. Effect of propionyl-L-carnitine on a background of monitored exercise in patients with claudication secondary to peripheral artery disease. J Cardiopulm Rehabil Prev 2011;31:125-32. PubMed

    Tolcapone

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

Reported for Propionyl-l-carnitine but not commonly for Tolcapone: back pain.

Effects for Tolcapone come from the ADVERSE REACTIONS section of its FDA label; effects for Propionyl-l-carnitine 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.

Everything else you take

See Every Supplement That Interacts With Tolcapone

This page covers Propionyl-l-carnitine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tolcapone page lists 58 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Ashwagandha (moderate).

By severity: 4 major · 45 moderate · 9 minor.

Open the Tolcapone interaction page

One more smart check

Taking Propionyl-l-carnitine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 57 real supplement products containing Propionyl-l-carnitine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Propionyl-l-carnitine. Even though Propionyl-l-carnitine itself has no known interaction with Tolcapone, 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 Propionyl-l-carnitine and Tolcapone 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 Propionyl-l-carnitine
Steady interest

#1,115 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tolcapone
Steady interest

#2,399 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 Propionyl-l-carnitine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Propionyl-l-carnitine and Tolcapone 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 Propionyl-l-carnitine

What is Propionyl-l-carnitine?

  • Peripheral artery disease and leg pain
  • Heart and circulation support
  • Energy and exercise performance
  • Erectile dysfunction
  • Diabetic nerve pain

Propionyl-l-carnitine is a form of the amino acid derivative carnitine that the body uses to help turn fat into energy, and it is studied mostly for circulation problems like peripheral artery disease. Some evidence suggests it may help walking distance in people with poor leg circulation, but results are mixed and it is not a substitute for standard medical care. Talk to a pharmacist or doctor before using it, especially if you have a medical condition or take other medicines.

Capsules, tablets, oral powder

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

Propionyl-l-carnitine: dosing

There is no single official dose of PLC for supplement use, and the right amount can depend on the condition being studied and the specific product. They can help you decide whether PLC is appropriate for you and what amount makes sense.Do not assume more is better. Higher doses raise the chance of side effects without guaranteeing more benefit.

From our Propionyl-l-carnitine monograph — the full record covers uses, side effects and every documented interaction.

Read the full Propionyl-l-carnitine monograph & all interactions
Medication

About Tolcapone

What Is Tolcapone Used For?

Brand name: Tasmar

Tolcapone tablets are used as an add-on treatment to levodopa and carbidopa for idiopathic Parkinson's disease (Parkinson's disease with no known cause). Both Tasmar and tolcapone tablets (generic) carry this indication.

Because of a serious risk of liver failure, tolcapone is ordinarily reserved for patients who are experiencing symptom fluctuations — such as "wearing-off" episodes between doses — and who are not responding satisfactorily to, or are not appropriate candidates for, other add-on therapies.

Most-Reported Side Effects for Tolcapone

From FAERS, the FDA’s public side-effect reporting system (349 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fall 30 reports
Hallucination 27 reports
Dyskinesia 26 reports
Pneumonia 20 reports
General physical health deterioration 19 reports
See full Tolcapone drug information
Keep checking

Other Drugs & Propionyl-l-carnitine

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

0Major
19Moderate
0Minor
2,810No known interaction
19 Moderate 2,810 No interaction
Moderate

19 interactions

No interaction 2,810 drugs checked — show the list

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

Showing the 60 most looked-up of 2,810 medications checked with no known interaction — see the full Propionyl-l-carnitine list.

See the full Propionyl-l-carnitine interactions page
See every supplement checked against Tolcapone, ranked by severity
Evidence & sources

Propionyl-l-carnitine References

The 12 references that drive our Propionyl-l-carnitine 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. Cherchi A, Lai C, Onnis E, et al. Propionyl carnitine in stable effort angina. Cardiovasc Drugs Ther 1990;4:481-6. PubMed
  2. Bartels GL, Remme WJ, den Hartog FR, et al. Additional anti-ischemic effects of long-term L-propionylcarnitine in anginal patients treated with conventional antianginal therapy. Cardiovasc Drugs Ther 1995;9:749-53.
  3. Caponnetto S, Canale C, Masperone MA, et al. Efficacy of L-propionylcarnitine treatment in patients with left ventricular dysfunction. Eur Heart J 1994;15:1267-73. PubMed
  4. 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
  5. Martinez E, Domingo P, Roca-Cusachs A. Potentiation of acenocoumarol action by L-carnitine. J Intern Med 1993;233:94.
  6. Bachmann HU, Hoffmann A. Interaction of food supplement L-carnitine with oral anticoagulant acenocoumarol. Swiss Med Wkly 2004;134:385. PubMed
  7. Gentile V, Vicini P, Prigiotti G, et al. Preliminary observations on the use of propionyl-L-carnitine in combination with sildenafil in patients with erectile dysfunction and diabetes. Curr Med Res Opin 2004;20:1377-84. PubMed
  8. 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
  9. Brass EP, Koster D, Hiatt WR, Amato A. A systematic review and meta-analysis of propionyl-L-carnitine effects on exercise performance in patients with claudication. Vasc Med 2013;18:3-12.
  10. Hiatt WR, Creager MA, Amato A, Brass EP. Effect of propionyl-L-carnitine on a background of monitored exercise in patients with claudication secondary to peripheral artery disease. J Cardiopulm Rehabil Prev 2011;31:125-32. PubMed
  11. Jacobs PL, Goldstein ER, Blackburn W, et al. Glycine propionyl-L-carnitine produces enhanced anaerobic work capacity with reduced lactate accumulation in resistance trained males. J Int Soc Sports Nutr 2009;6:9. PubMed
  12. Jacobs PL, Goldstein ER. Long-term glycine propionyl-l-carnitine supplementation and paradoxical effects on repeated anaerobic sprint performance. J Int Soc Sports Nutr 2010;7:35.

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 Propionyl-l-carnitine and Tolcapone Together: Common Questions

Is it safe to take Propionyl-l-carnitine with Tolcapone?
We do not list a known interaction between Propionyl-l-carnitine and Tolcapone. 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 Propionyl-l-carnitine and Tolcapone 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 Propionyl-l-carnitine and Tolcapone combination checked?
Interactions in our licensed database are recorded against drug classes. Tolcapone is filed under 3 classifications, and Propionyl-l-carnitine has documented interactions with 3 drug classes — none of Tolcapone'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 Propionyl-l-carnitine interact with any other medications?
Yes. Propionyl-l-carnitine has 19 documented drug interactions in our database — Tolcapone 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 Tolcapone interact with any supplements?
Yes. Tolcapone has documented interactions with 58 supplements in our database — Propionyl-l-carnitine is not one of them. The Tolcapone 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

Propionyl-l-carnitine monograph Uses, safety profile, and every drug interaction in one place Tolcapone drug information The full plain-English guide to this medication Tolcapone supplement interactions Every supplement checked against Tolcapone, 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 Tolcapone and Propionyl-l-carnitine?

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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.