Drug & supplement interaction

Kefir + Simvastatin

Simvastatin brand name: Zocor.

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 Kefir and Simvastatin 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Kefir and Simvastatin

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 Simvastatin and Kefir 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.

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.

Kefir safety at a glance

Kefir overall Generally safe Kefir is generally safe for most healthy people as a food.
Pregnancy Use caution Pasteurized-milk kefir is likely fine, but avoid unpasteurized or homemade versions and consult your doctor.
Breastfeeding Use caution Likely fine as a food, but choose pasteurized products and check with your doctor.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Simvastatin and Kefir? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Simvastatin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Simvastatin is filed under 8 classifications — including hmg-coa reductase inhibitors ("statins"), organic anion-transporting polypeptide substrates (oatp), glucuronidated drugs. Kefir has documented interactions with 2 drug classes — the most serious being immunosuppressants (moderate) and disulfiram (antabuse) (minor) — and none of Simvastatin’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Kefir Does Interact With Other Medications

Kefir has 121 moderate, 1 minor known drug interactions in our database — Simvastatin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 121 Minor 1 No known interaction 2,708 (incl. Simvastatin)
Taking anything else?

Check Another of Your Medications Against Kefir

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

What to actually watch for

No Interaction Found — But Data Suggests Kefir and Simvastatin May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Constipation / Stomach pain / Nausea reported in 5.3% of FDA reports for Simvastatin Additional detail

    Kefir

    “Orally, kefir might cause bloating, nausea, intestinal cramping, diarrhea, and constipation with initial use. These symptoms are uncommon and usually resolve after continued use. However, severe bloating and abdominal cramping resulting in withdrawal from a clinical trial has been reported for 3 patients.”

    Kefir · Natural Medicines adverse-effect record, reported in constipation.

    4 sources cited
    1. 7636. St-Onge MP, Farnworth ER, Savard T, et al. Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810]. BMC Complement Altern Med 200 PubMed
    2. 95314. Turan I, Dedeli Ö, Bor S, Ilter T. Effects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: a pilot study. Turk J Gastroenterol. 2014;25(6):650-6. PubMed
    3. 112046. Bellikci-Koyu E, Sarer-Yurekli BP, Karagozlu C, Aydin-Kose F, Ozgen AG, Buyuktuncer Z. Probiotic kefir consumption improves serum apolipoprotein A1 levels in metabolic syndrome patients: a randomized controlled clinical trial. Nutr Res 2022;102:59-70. PubMed
    4. 95311. Fathi Y, Faghih S, Zibaeenezhad MJ, Tabatabaei SH. Kefir drink leads to a similar weight loss, compared with milk, in a dairy-rich non-energy-restricted diet in overweight or obese premenopausal women: a randomized controlled trial. Eur J Nutr. 2016;55(1) PubMed

    Simvastatin

    Listed in the ADVERSE REACTIONS section of the FDA label for Simvastatin, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Kefir but not commonly for Simvastatin: diarrhea and bloating or gas.

Effects for Simvastatin come from the ADVERSE REACTIONS section of its FDA label; effects for Kefir come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 261,345 voluntary FDA FAERS reports for Simvastatin that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Simvastatin Is Prescribed For, and What Kefir Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Simvastatin is a prescription medicine with approved uses on its FDA label. Kefir is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Simvastatin is prescribed for: Simvastatin tablets are used alongside a cholesterol-lowering diet to treat high LDL cholesterol (bad cholesterol), high triglycerides, and certain inherited cholesterol disorders, including heterozygous familial hypercholesterolemia (HeFH) in adults and children aged 10 and older, and homozygous familial hypercholesterolemia (HoFH) in adults. In adults who already have coronary heart disease, cerebrovascular disease, peripheral vascular disease, or diabetes and are at high risk for heart events, simvastatin is also used to reduce the risk of death from heart disease, non-fatal heart attack, stroke, and the need for procedures to open blocked arteries. Zocor is one brand-name product containing simvastatin and carries these same indications.

Kefir has been studied for:

  • Hypercholesterolemia studied, not established Kefir has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Kefir for hypercholesterolemia

    It is unclear if oral kefir is beneficial in patients with hypercholesterolemia.

  • Diabetes studied, not established Kefir has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Kefir for diabetes

    It is unclear if oral kefir is beneficial in patients with diabetes.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Simvastatin on your own; if you are taking Kefir for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Kefir or Simvastatin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Kefir or Simvastatin, 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 Simvastatin

This page covers Kefir only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Simvastatin page lists 183 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Beer (major), Grapefruit (major) and Siberian Cocklebur (major).

By severity: 8 major · 139 moderate · 36 minor.

Open the Simvastatin interaction page

One more smart check

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

We hold 29 real supplement products containing Kefir, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Kefir. Even though Kefir itself has no known interaction with Simvastatin, 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 Kefir and Simvastatin 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 Kefir
Steady interest

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

29 days ago today
Medication Simvastatin
Top 25%

#462 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 Kefir reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Kefir and Simvastatin records this page draws on were last updated July 10, 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 Kefir

What is Kefir?

  • Digestive health
  • Source of probiotics
  • Lactose intolerance support
  • General immune support
  • Gut microbiome balance

Kefir is a fermented drink made by adding kefir grains to milk (or sugar water), creating a tangy beverage rich in probiotics. It is generally a safe, nutritious food that may support gut health, but strong evidence for treating specific medical conditions is still limited. If you have a weakened immune system or other health concerns, check with your pharmacist or doctor first.

Fermented milk or water with kefir grains (a culture of bacteria and yeast) · Drinkable fermented milk, water kefir, powdered or capsule probiotic products

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

Kefir: dosing

There is no official standardized dose for kefir because it is a food, not a regulated medicine. Many people drink anywhere from a few ounces to a cup per day, often starting small and increasing gradually to allow the gut to adjust.If you use a powdered or capsule probiotic product, follow the directions on the label.

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

Read the full Kefir monograph & all interactions
Medication

About Simvastatin

What Is Simvastatin Used For?

Brand name: Zocor

Simvastatin tablets are used alongside a cholesterol-lowering diet to treat high LDL cholesterol (bad cholesterol), high triglycerides, and certain inherited cholesterol disorders, including heterozygous familial hypercholesterolemia (HeFH) in adults and children aged 10 and older, and homozygous familial hypercholesterolemia (HoFH) in adults.

In adults who already have coronary heart disease, cerebrovascular disease, peripheral vascular disease, or diabetes and are at high risk for heart events, simvastatin is also used to reduce the risk of death from heart disease, non-fatal heart attack, stroke, and the need for procedures to open blocked arteries. Zocor is one brand-name product containing simvastatin and carries these same indications.

Most-Reported Side Effects for Simvastatin

From FAERS, the FDA’s public side-effect reporting system (263,006 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 14,524 reports
Nausea 14,119 reports
Dyspnea 13,226 reports
Diarrhea 12,591 reports
Dizziness 11,830 reports
See full Simvastatin drug information
Keep checking

Other Drugs & Kefir

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

0Major
121Moderate
1Minor
2,707No known interaction
121 Moderate 1 Minor 2,707 No interaction
Moderate

121 interactions

Showing 60 of 121 moderate interactions — see all 121 on the Kefir page.

Minor

1 interaction

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Kefir list.

See the full Kefir interactions page
See every supplement checked against Simvastatin, ranked by severity
Evidence & sources

Kefir References

The 10 references that drive our Kefir 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. St-Onge MP, Farnworth ER, Savard T, et al. Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810]. BMC Complement Altern Med 200 PubMed
  2. Murofushi M, Mizuguchi J, Aibara K, Matuhasi T. Immunopotentiative effect of polysaccharide from kefir grain, KGF-C, administered orally in mice. Immunopharmacology 1986;12:29-35. PubMed
  3. Shiomi M, Sasaki K, Murofushi M, Aibara K. Antitumor activity in mice of orally administered polysaccharide from Kefir grain. Jpn J Med Sci Biol 1982;35:75-80. PubMed
  4. Rimada PS, Abraham AG. Polysaccharide production by kefir grains during whey fermentation. J Dairy Res 2001;68:653-61. PubMed
  5. De Vrese M, Keller B, Barth CA. Enhancement of intestinal hydrolysis of lactose by microbial beta-galactosidase (EC 3.2.1.23) of kefir. Br J Nutr 1992;67:67-75.
  6. Athanasiadis, I., Boskou, D., Kanellaki, M., and Koutinas, A. A. Low-temperature alcoholic fermentation by delignified cellulosic material supported cells of kefir yeast. J.Agric.Food Chem. 1999;47(10):4474-4477. PubMed
  7. Rabl, W., Liniger, B., Sutter, K., and Sigrist, T. [Ethanol content of Kefir water]. Blutalkohol 1994;31(2):76-79.
  8. Fathi Y, Faghih S, Zibaeenezhad MJ, Tabatabaei SH. Kefir drink leads to a similar weight loss, compared with milk, in a dairy-rich non-energy-restricted diet in overweight or obese premenopausal women: a randomized controlled trial. Eur J Nutr. 2016;55(1) PubMed
  9. Turan I, Dedeli Ö, Bor S, Ilter T. Effects of a kefir supplement on symptoms, colonic transit, and bowel satisfaction score in patients with chronic constipation: a pilot study. Turk J Gastroenterol. 2014;25(6):650-6. PubMed
  10. Bellikci-Koyu E, Sarer-Yurekli BP, Karagozlu C, Aydin-Kose F, Ozgen AG, Buyuktuncer Z. Probiotic kefir consumption improves serum apolipoprotein A1 levels in metabolic syndrome patients: a randomized controlled clinical trial. Nutr Res 2022;102:59-70. PubMed

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 Kefir and Simvastatin Together: Common Questions

Is it safe to take Kefir with Simvastatin?
We do not list a known interaction between Kefir and Simvastatin. 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.
Do Kefir and Simvastatin have any of the same side effects?
Yes — our sources link each of them separately to 3 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Kefir and Simvastatin used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Kefir in each. That is a conversation for your prescriber, especially if Simvastatin is being adjusted to a target.
How was the Kefir and Simvastatin combination checked?
Interactions in our licensed database are recorded against drug classes. Simvastatin is filed under 8 classifications, and Kefir has documented interactions with 2 drug classes — none of Simvastatin's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Kefir interact with any other medications?
Yes. Kefir has 122 documented drug interactions in our database — Simvastatin is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Simvastatin interact with any supplements?
Yes. Simvastatin has documented interactions with 183 supplements in our database — Kefir is not one of them. The Simvastatin 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

Kefir monograph Uses, safety profile, and every drug interaction in one place Simvastatin drug information The full plain-English guide to this medication Simvastatin supplement interactions Every supplement checked against Simvastatin, 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Simvastatin and Kefir?

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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.