Drug & supplement interaction

Testolone + Tolcapone

Tolcapone brand name: Tasmar.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Testolone has a moderate interaction with Tolcapone. Theoretically, concomitant use might have additive hepatotoxic effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Testolone and Tolcapone

Here is the interaction we found between these two, with the evidence behind it.

Moderate

HEPATOTOXIC DRUGS

Why this applies to Tolcapone

Tolcapone falls under HEPATOTOXIC DRUGS — the group Testolone interacts with.

Theoretically, concomitant use might have additive hepatotoxic effects.
In a case report, a 52-year-old male was diagnosed with liver injury thought to be related to the use of products containing testolone. Also, elevated liver enzymes were commonly reported in a dose escalation study of testolone.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the concern with pairing these two. Tolcapone (Tasmar) is already known to be hard on the liver, so much so that anyone taking it needs regular blood tests to watch their liver enzymes. Testolone (RAD-140) has its own track record of liver trouble, including a case report of liver injury and raised liver enzymes in a dosing study.

Put them together and you may be stacking two liver stressors on top of each other. Warning signs of liver strain include yellowing of the skin or eyes, dark urine, belly pain, nausea, or unusual tiredness. Keep in mind Testolone is an unapproved, illegally sold product I wouldn't recommend at all. Please talk with your doctor or pharmacist before combining anything with tolcapone.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. LoRusso P, Hamilton E, Ma C, et al. A first-in-human phase 1 study of a novel selective androgen receptor modulator (SARM), RAD140, in ER+/HER2- metastatic breast cancer. Clin Breast Cancer 2022;22(1):67-77. PubMed
  2. Barbara M, Dhingra S, Mindikoglu AL. Drug-induced liver injury associated with alpha bolic (RAD-140) and alpha elite (RAD-140 and LGD-4033). ACG Case Rep J 2020;7(6):e00409. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Testolone Also Interacts With Other Medications

Testolone has 369 moderate known drug interactions in our database — the Tolcapone one above is one of them. If you take anything else, check it against the full list below.

Moderate 369 No known interaction 2,461 (incl. Tolcapone)
Taking anything else?

Check Another of Your Medications Against Testolone

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

Everything else you take

See Every Supplement That Interacts With Tolcapone

This page covers Testolone 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 Testolone as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9 real supplement products containing Testolone, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Testolone. Your product may carry other ingredients that interact with Tolcapone too, on top of Testolone — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Testolone 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 Testolone
Top half

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

29 days ago today
Medication Tolcapone
Steady interest

#2,395 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.

Supplement

About Testolone

What is Testolone?

  • Muscle building
  • Athletic performance and bodybuilding
  • Strength gains
  • Body recomposition (fat loss with muscle gain)

Testolone (RAD-140) is a synthetic experimental drug called a selective androgen receptor modulator (SARM), not a dietary supplement or herb, and it is not approved or proven safe for human use. It is illegally sold for muscle building, has been linked to serious harms including liver injury, and is banned in sports — it should not be taken outside of supervised clinical research.

Read the full Testolone 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.

See full Tolcapone drug information
Keep checking

Other Drugs & Testolone

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

0Major
369Moderate
0Minor
2,460No known interaction
369 Moderate 2,460 No interaction
Moderate

369 interactions

Showing 60 of 369 moderate interactions — see all 369 on the Testolone page.

No interaction 2,460 drugs checked — show the list

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

Showing the 60 most looked-up of 2,460 medications checked with no known interaction — see the full Testolone list.

See the full Testolone interactions page
See every supplement checked against Tolcapone, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

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

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
Testolone monograph › Uses, safety, and every drug interaction in one place Tolcapone supplement interactions › Every supplement checked against Tolcapone, ranked by severity Tolcapone drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Testolone and Tolcapone Together: Common Questions

Can you take Testolone with Tolcapone?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Testolone and Tolcapone interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Tolcapone and Testolone?

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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.