Drug & supplement interaction

Buchu + Nirmatrelvir, Ritonavir

Nirmatrelvir, Ritonavir brand name: Paxlovid.

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

Buchu has a moderate interaction with Nirmatrelvir, Ritonavir. 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 Nirmatrelvir, Ritonavir

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Nirmatrelvir, Ritonavir

Nirmatrelvir, Ritonavir 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 gist with Paxlovid (nirmatrelvir plus ritonavir) and buchu. Buchu's essential oil contains a compound called pulegone, which can be hard on the liver in large amounts. The ritonavir part of Paxlovid is also known to occasionally stress the liver. So the worry is simply that stacking two things that lean on the liver could add up and raise your risk of liver trouble.

This is theoretical, based on how these substances behave, not on real cases of people taking them together. Paxlovid is also a short course, usually just five days. Still, if you ever notice yellowing skin or eyes, dark urine, belly pain, or unusual tiredness, contact your doctor. Casual culinary use matters less than concentrated buchu oil or capsules. Please check with your pharmacist before combining them.

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 Nirmatrelvir, Ritonavir 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. Nirmatrelvir, Ritonavir)
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 Nirmatrelvir, Ritonavir

This page covers Buchu only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nirmatrelvir, Ritonavir page lists 176 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Grapefruit (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 134 moderate · 36 minor.

From our pharmacist’s overview on the Nirmatrelvir, Ritonavir page

“Paxlovid (nirmatrelvir and ritonavir) deserves genuine care around supplements, mostly because its ritonavir component strongly blocks the liver enzyme CYP3A4. The bulk of this list is made up of ingredients that enzyme normally clears, so their levels can climb unpredictably during the five-day course.”

Reviewed by 2 · Jul 18, 2026

Open the Nirmatrelvir, Ritonavir 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 Nirmatrelvir, Ritonavir 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 Nirmatrelvir, Ritonavir 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%

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

29 days ago today
Medication Nirmatrelvir, Ritonavir
Top half

#878 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 Nirmatrelvir and Ritonavir

What Is Nirmatrelvir and Ritonavir Used For?

Brand name: Paxlovid

Paxlovid is approved to treat mild-to-moderate COVID-19 in adults who are at high risk of progressing to severe disease — meaning hospitalization or death. It is intended for people who already have symptoms and a confirmed COVID-19 diagnosis.

Paxlovid is not approved to prevent COVID-19 before or after exposure. It is a treatment, not a preventive medication.

See full Nirmatrelvir and Ritonavir 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 Nirmatrelvir, Ritonavir, 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 Nirmatrelvir, Ritonavir supplement interactions › Every supplement checked against Nirmatrelvir, Ritonavir, ranked by severity Nirmatrelvir and Ritonavir 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 Nirmatrelvir, Ritonavir Together: Common Questions

Can you take Buchu with Nirmatrelvir, Ritonavir?
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 Nirmatrelvir, Ritonavir 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 Nirmatrelvir, Ritonavir 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.