Drug & supplement interaction

Saigon Cinnamon + Nirmatrelvir, Ritonavir

Nirmatrelvir, Ritonavir brand name: Paxlovid.

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

Saigon Cinnamon has a moderate interaction with Nirmatrelvir, Ritonavir. Theoretically, Saigon cinnamon might cause additive effects when used with hepatotoxic drugs.

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

Saigon Cinnamon 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 Saigon Cinnamon interacts with.

Theoretically, Saigon cinnamon might cause additive effects when used with hepatotoxic drugs.
Saigon cinnamon contains coumarin. Coumarin has caused hepatotoxicity in animal models. In otherwise healthy humans, very high doses of coumarin, from 50-7000 mg daily, can result in hepatotoxicity that resolves when coumarin use is discontinued. Lower amounts might also cause liver problems in sensitive people, such as those with liver disease or those taking potentially hepatotoxic agents.
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 to know about pairing Saigon cinnamon with Paxlovid. This isn't about cinnamon changing how the drug works or how fast your body clears it. Instead, it's a concern about your liver. Saigon cinnamon is a cassia type that's naturally high in coumarin, a compound that, in big or regular supplement doses, can stress the liver in sensitive people.

Paxlovid (especially the ritonavir part) can also affect the liver, so the worry is simply an additive load. Honestly, this is theoretical and based on the chemistry, not strong human studies. A sprinkle of cinnamon on your oatmeal is very unlikely to matter. Concentrated cinnamon capsules during your short Paxlovid course are where I'd pause. Watch for yellowing skin, dark urine, or belly pain, and check with your pharmacist before adding a supplement.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Press release. Cinnamon capsules to reduce blood sugar are medicinal products! Efficacy has not been scientifically proven - some products contain high levels of coumarin. Federal Institute of Risk Assessment (BfM), Germany, November 11, 2006. Available a
  2. Felter SP, Vassallo JD, Carlton BD, Daston GP. A safety assessment of coumarin taking into account species-specificity of toxicokinetics. Food Chem Toxicol 2006;44:462-75. PubMed
  3. Choi, J., Lee, K. T., Ka, H., Jung, W. T., Jung, H. J., and Park, H. J. Constituents of the essential oil of the Cinnamomum cassia stem bark and the biological properties. Arch Pharm Res 2001;24(5):418-423.
  4. Wang YH, Avula B, Nanayakkara NP, Zhao J, Khan IA. Cassia cinnamon as a source of coumarin in cinnamon-flavored food and food supplements in the United States. J Agric Food Chem. 2013;61(18):4470-6. 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

Saigon Cinnamon Also Interacts With Other Medications

Saigon Cinnamon has 369 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 369 No known interaction 2,461 (incl. Nirmatrelvir, Ritonavir)
Taking anything else?

Check Another of Your Medications Against Saigon Cinnamon

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

Everything else you take

See Every Supplement That Interacts With Nirmatrelvir, Ritonavir

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

We hold 4 real supplement products containing Saigon Cinnamon, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Saigon Cinnamon. Your product may carry other ingredients that interact with Nirmatrelvir, Ritonavir too, on top of Saigon Cinnamon — 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 Saigon Cinnamon 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 Saigon Cinnamon
Steady interest

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

29 days ago today
Medication Nirmatrelvir, Ritonavir
Top half

#814 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 Saigon Cinnamon

What is Saigon Cinnamon?

  • Blood sugar support
  • Digestive upset
  • Antioxidant support
  • Flavoring and culinary use
  • Antimicrobial

Saigon cinnamon is a flavorful spice from a Cinnamomum tree grown mainly in Vietnam, and it is a type of 'cassia' cinnamon. Some people use it for blood sugar and digestion, but the human evidence is limited. Because cassia cinnamons like this one are high in a compound called coumarin, regularly taking large supplement doses may be hard on the liver in sensitive people, so use food amounts and check with your pharmacist before taking concentrated products.

Read the full Saigon Cinnamon 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 & Saigon Cinnamon

Browse every other medication we’ve checked against Saigon Cinnamon — 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 Saigon Cinnamon page.

No interaction 2,460 drugs checked — show the list

We also checked Saigon Cinnamon 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 Saigon Cinnamon list.

See the full Saigon Cinnamon 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
Saigon Cinnamon 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 Saigon Cinnamon and Nirmatrelvir, Ritonavir Together: Common Questions

Can you take Saigon Cinnamon 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 Saigon Cinnamon 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 Saigon Cinnamon?

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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.