Drug & supplement interaction

Buchu + Selpercatinib

Selpercatinib brand name: Retevmo.

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

Buchu has a moderate interaction with Selpercatinib. Buchu contains pulegone, a known hepatotoxin.

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

Buchu and Selpercatinib

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Selpercatinib

Selpercatinib falls under HEPATOTOXIC DRUGS — the group Buchu interacts with.

Buchu contains pulegone, a known hepatotoxin. There is some concern that buchu may adversely affect the liver, especially when the leaf is used in large doses or the oil is ingested. Theoretically, concomitant use with hepatotoxic drugs might increase the risk of liver damage. Some of these drugs include acarbose (Precose, Prandase), amiodarone (Cordarone), atorvastatin (Lipitor), azathioprine (Imuran), carbamazepine (Tegretol), cerivastatin (Baycol), diclofenac (Voltaren), felbamate (Felbatol), fenofibrate (Tricor), fluvastatin (Lescol), gemfibrozil (Lopid), isoniazid, itraconazole, (Sporanox), ketoconazole (Nizoral), leflunomide (Arava), lovastatin (Mevacor), methotrexate (Rheumatrex), nevirapine (Viramune), niacin, nitrofurantoin (Macrodantin), pioglitazone (Actos), pravastatin (Pravachol), pyrazinamide, rifampin (Rifadin), ritonavir (Norvir), rosiglitazone (Avandia), simvastatin (Zocor), tacrine (Cognex), tamoxifen, terbinafine (Lamisil), valproic acid, and zileuton (Zyflo)
Severity Moderate Likelihood Possible Evidence D

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 simple version: Selpercatinib (Retevmo) can be tough on your liver on its own, and your cancer team already keeps an eye on your liver enzymes while you take it. Buchu contains a compound called pulegone, which in large amounts (especially the concentrated oil) may also stress the liver. Stacking two things that can irritate the liver is the concern here.

I'll be honest with you: this is a theoretical caution based on how these compounds behave, not on real patient cases, so don't panic. Still, with a serious medicine like this, I wouldn't add concentrated buchu oil or high-dose supplements without checking first. Watch for yellowing skin or eyes, dark urine, belly pain, or unusual tiredness, and please run any buchu product past your oncologist or pharmacist before starting.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Moolla A, Viljoen AM. 'Buchu' - Agathosma betulina and Agathosma crenulata (Retaceae): a review. J Ethnopharmacol 2008;119(3):413-9.

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

Buchu Also Interacts With Other Medications

Buchu has 480 moderate known drug interactions in our database — the Selpercatinib one above is one of them. If you take anything else, check it against the full list below.

Moderate 480 No known interaction 2,350 (incl. Selpercatinib)
Taking anything else?

Check Another of Your Medications Against Buchu

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

Everything else you take

See Every Supplement That Interacts With Selpercatinib

This page covers Buchu only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Selpercatinib page lists 178 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 11 major · 132 moderate · 35 minor.

From our pharmacist’s overview on the Selpercatinib page

“People facing a RET-driven lung or thyroid cancer often add supplements for strength, sleep, or immune support, and with selpercatinib (Retevmo) that instinct needs a careful check. Eleven of the 178 ingredients here carry a major rating, and the largest cluster affects how the drug is cleared by the CYP3A4 enzyme: St.”

Reviewed by 2 · Jul 18, 2026

Open the Selpercatinib interaction page

One more smart check

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

We hold 128 real supplement products containing Buchu, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Buchu. Your product may carry other ingredients that interact with Selpercatinib too, on top of Buchu — 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 Buchu and Selpercatinib 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 Buchu
Top 25%

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

29 days ago today
Medication Selpercatinib
Steady interest

#1,494 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 Buchu

What is Buchu?

Buchu
  • Urinary tract complaints
  • Diuretic (increasing urine flow)
  • Bloating and fluid retention
  • Mild digestive upset
  • Antimicrobial/antiseptic use
  • Flavoring and fragrance

Buchu is a fragrant South African shrub whose leaves are traditionally used for urinary and bladder complaints and as a diuretic. Solid human studies are lacking, so its benefits are largely unproven, and it should be avoided in pregnancy and breastfeeding. Talk to a pharmacist or doctor before using it, especially if you have kidney or liver problems.

Read the full Buchu monograph & all interactions
Medication

About Selpercatinib

What Is Selpercatinib Used For?

Brand name: Retevmo

Selpercatinib treats cancers driven by changes in the RET gene — either a gene fusion (where RET joins abnormally with another gene) or a RET mutation (a change in the gene itself). Your doctor will confirm one of these changes with an FDA-approved test before prescribing it.

It is approved for adults with RET fusion-positive non-small cell lung cancer; adults and children 2 and older with RET-mutant medullary thyroid cancer or RET fusion-positive thyroid cancer; and adults and children 2 and older with other advanced solid tumors that have a RET gene fusion and have not responded to prior treatment.

See full Selpercatinib drug information
Keep checking

Other Drugs & Buchu

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

0Major
480Moderate
0Minor
2,349No known interaction
480 Moderate 2,349 No interaction
Moderate

480 interactions

Showing 60 of 480 moderate interactions — see all 480 on the Buchu page.

No interaction 2,349 drugs checked — show the list

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

Showing the 60 most looked-up of 2,349 medications checked with no known interaction — see the full Buchu list.

See the full Buchu interactions page
See every supplement checked against Selpercatinib, 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
Buchu monograph › Uses, safety, and every drug interaction in one place Selpercatinib supplement interactions › Every supplement checked against Selpercatinib, ranked by severity Selpercatinib 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 Buchu and Selpercatinib Together: Common Questions

Can you take Buchu with Selpercatinib?
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 Buchu and Selpercatinib 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 Selpercatinib and Buchu?

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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.