Drug & supplement interaction

Black Haw + Tolcapone

Tolcapone brand name: Tasmar.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Black Haw 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.

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Interaction report

Black Haw 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 Black Haw 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.

Worth understanding: our licensed dataset holds no drug-interaction record for Black Haw at all — not against Tolcapone, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

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.

Black Haw safety at a glance

Black Haw overall Use caution Generally used in traditional medicine, but human safety data are limited.
Pregnancy Possibly Unsafe When used orally. Some evidence suggests black haw has uterine relaxant effects; avoid using. Read the full pregnancy detail
Breastfeeding Avoid Not enough safety information exists for nursing mothers.

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.

Still wondering about combining Tolcapone and Black Haw? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Tolcapone’s Own FDA Label Lists

This is not an interaction — none of it involves Black Haw. These are the most notable effects listed in the ADVERSE REACTIONS section of Tolcapone’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • A stroke or mini-stroke Worth acting on
  • Pain or burning when passing urine Worth acting on
  • Memory problems Worth acting on
  • Dehydration Worth acting on
  • Trouble swallowing Worth acting on
  • Bleeding in the gut Worth acting on
  • Trouble passing urine Worth acting on
  • A slow heartbeat Worth acting on
  • Blood clots Worth acting on
  • Hallucinations Worth acting on

Showing the 10 most notable of 69 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Tolcapone. Read the label on DailyMed › Black Haw’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Black Haw side to compare — that is a limit of the record, not a statement that Black Haw has no side effects.

Special populations

Black Haw in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally. Some evidence suggests black haw has uterine relaxant effects; avoid using.

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

Everything else you take

See Every Supplement That Interacts With Tolcapone

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

We hold 20 real supplement products containing Black Haw, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Haw. Even though Black Haw 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 Black Haw 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 Black Haw
Steady interest

#1,176 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tolcapone
Steady interest

#2,380 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 Black Haw reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Black Haw 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 Black Haw

What is Black Haw?

Black Haw
  • Menstrual cramps
  • Uterine spasms
  • Threatened miscarriage (traditional)
  • Menopause-related discomfort
  • General muscle cramps

Black Haw is a traditional herbal bark long used to ease menstrual cramps and uterine spasms, but modern human studies are very limited. It contains compounds that may relax smooth muscle, but its effectiveness is not well proven, and it should be used with caution, especially during pregnancy. Talk to a pharmacist or doctor before trying it.

Viburnum prunifolium · Adoxaceae · Bark of the stem and root · Tea (decoction), tincture, liquid extract, capsules, dried bark

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

Black Haw: dosing

There is no established standardized dose for Black Haw. Traditional preparations include teas (decoctions of the bark), tinctures, and liquid extracts, but reliable dosing has not been confirmed by modern research.If you choose to use a product, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Black Haw 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 & Black Haw

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Black Haw list.

See the full Black Haw interactions page
See every supplement checked against Tolcapone, ranked by severity
Evidence & sources

Black Haw References

The 1 references that drive our Black Haw 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. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.

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 Black Haw and Tolcapone Together: Common Questions

Is it safe to take Black Haw with Tolcapone?
We do not list a known interaction between Black Haw 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.
Does Tolcapone interact with any supplements?
Yes. Tolcapone has documented interactions with 58 supplements in our database — Black Haw 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

Black Haw 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 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Tolcapone and Black Haw?

Our pharmacists answer your medication & supplement questions — free.

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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.