Drug & supplement interaction

Cranberry + Nirmatrelvir, Ritonavir

Nirmatrelvir, Ritonavir brand name: Paxlovid.

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

Cranberry has a moderate interaction with Nirmatrelvir, Ritonavir. Theoretically, cranberry might increase the levels and adverse effects of CYP3A4 substrates.

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

Cranberry and Nirmatrelvir, Ritonavir

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Nirmatrelvir, Ritonavir

Nirmatrelvir, Ritonavir falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Cranberry interacts with.

Theoretically, cranberry might increase the levels and adverse effects of CYP3A4 substrates.
A case of upper back pain, rhabdomyolysis, and abnormal liver function has been reported for a patient taking atorvastatin, a CYP3A4 substrate, in combination with cranberry juice 16 ounces daily for 2 weeks. Creatinine kinase and liver enzymes normalized within 2 weeks of stopping cranberry juice. Also, animal research suggests that cranberry juice, administered intraduodenally 30 minutes prior to nifedipine, a CYP3A4 substrate, inhibits nifedipine metabolism and increases the area under the concentration-time curve by 1.6-fold compared to control.
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 thing about Paxlovid: the ritonavir part is actually a deliberate CYP3A4 blocker, included on purpose to slow the breakdown of nirmatrelvir so it stays at a useful level. Cranberry has been suggested, mostly in theory and from a single case report with a different drug, to mildly slow that same CYP3A4 pathway. So if it did anything at all, it would nudge nirmatrelvir levels up a touch, possibly meaning a bit more of side effects like an odd taste in the mouth, nausea, diarrhea, or muscle aches.

Honestly, the evidence here is weak and the effect would be small next to ritonavir's strong, intentional one. A regular glass of cranberry juice is unlikely to matter. Paxlovid is also short, just five days, so the overlap is brief. Still, run it by your pharmacist to be safe.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Uesawa, Y. and Mohri, K. Effects of cranberry juice on nifedipine pharmacokinetics in rats. J Pharm Pharmacol 2006;58(8):1067-1072. PubMed
  2. Doad GJ, Kabange W. Cranberry juice, atorvastatin and back pain. J Med Assoc Ga 2014;103(1):14.

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

Cranberry Also Interacts With Other Medications

Cranberry has 642 moderate, 69 minor 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 642 Minor 69 No known interaction 2,119 (incl. Nirmatrelvir, Ritonavir)
Taking anything else?

Check Another of Your Medications Against Cranberry

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

From our Q&A

Questions About Cranberry or Nirmatrelvir, Ritonavir

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Cranberry or Nirmatrelvir, Ritonavir, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Nirmatrelvir, Ritonavir

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

We hold 5,249 real supplement products containing Cranberry, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cranberry. Your product may carry other ingredients that interact with Nirmatrelvir, Ritonavir too, on top of Cranberry — 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 Cranberry 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 Cranberry
Top 5%

#55 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 Cranberry

What is Cranberry?

Cranberry
  • Urinary tract infection prevention
  • Bladder health
  • Antioxidant support
  • Source of vitamin C

Cranberry is best known for helping to prevent repeated urinary tract infections (UTIs) in some people, and the evidence here is moderate but mixed. It is not a reliable treatment for an active UTI, which usually needs antibiotics. For most people cranberry products are well tolerated, but check with a pharmacist before relying on them, especially if you have frequent infections.

Read the full Cranberry 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 & Cranberry

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

0Major
642Moderate
69Minor
2,118No known interaction
642 Moderate 69 Minor 2,118 No interaction
Moderate

642 interactions

Showing 60 of 642 moderate interactions — see all 642 on the Cranberry page.

Minor

69 interactions

Showing 60 of 69 minor interactions — see all 69 on the Cranberry page.

No interaction 2,118 drugs checked — show the list

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

Showing the 60 most looked-up of 2,118 medications checked with no known interaction — see the full Cranberry list.

See the full Cranberry 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
Cranberry 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 Cranberry and Nirmatrelvir, Ritonavir Together: Common Questions

Can you take Cranberry 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 Cranberry 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 Cranberry?

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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.