Herb & supplement monograph

Kefir Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Kefir interacts with medications. The heart of this page is the interaction list — every drug Kefir is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Kefir is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Kefir Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Kefir drug interaction appears low for most people. None of the listed interactions are rated major, and every concern in the profile is theoretical rather than documented in human studies.

Interactions deserving the most attention

The interactions that deserve the most attention involve immunosuppressants, the medicines that lower immune activity, such as those used after an organ transplant. Because kefir contains live, actively growing bacteria and yeast, there is a theoretical concern that it could raise the risk of bacterial or yeast infections in someone whose immune defenses are suppressed. There is also a minor, theoretical concern with disulfiram, since kefir may contain small amounts of alcohol that could trigger a disulfiram reaction. Neither concern has been confirmed in human studies.

What the rest of the list means

Although kefir is linked to a fairly long list of medications, nearly all of them fall under one theme: the possibility that its live microbes could pose a problem when the immune system is weakened by medication. That means the length of the list does not signal many separate dangers. For people not taking these medicines, the profile shows no known reason for concern.

Check your medications against Kefir

Based on HelloPharmacist’s Kefir interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Kefir

122 medications have a known interaction with Kefir, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Kefir using our pharmacist-reviewed interaction data.

AI summaries are generated from our Kefir interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction 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.
Possible. 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
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Kefir combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Kefir affects

Every type of medication (drug category) Kefir is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Kefir interacts with

ImmunosuppressantsDisulfiram (antabuse)

Immunosuppressants

Theoretically, kefir might increase the risk of bacterial and yeast infections in patients taking immunosuppressants.

Kefir contains actively growing bacteria and yeast.

Likelihood Possible Evidence D

Disulfiram (Antabuse)

Theoretically, taking kefir with disulfiram might cause a disulfiram reaction.

Kefir may contain alcohol.

Likelihood Possible Evidence D

Monograph

Kefir: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

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.

Part used: Fermented milk or water with kefir grains (a culture of bacteria and yeast)
Common forms: Drinkable fermented milk, water kefir, powdered or capsule probiotic products

People commonly use it for

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

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallLikely safe

Kefir is generally safe for most healthy people as a food.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail

BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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Overview

Kefir is a fermented drink that is usually made from milk, though a dairy-free version called water kefir is made with sugar water. It is created by adding small, gel-like clusters called kefir grains to the liquid. These grains are not true grains like wheat or rice. Instead, they are a living culture of friendly bacteria and yeast held together in a matrix.

As the grains ferment the milk or water over about 24 hours, they produce a tangy, slightly fizzy drink. Kefir has been used for centuries, with roots traced to the Caucasus Mountains region. Today it is sold in many grocery stores and is also made at home.

People drink kefir as a nutritious food and a natural source of probiotics (helpful live microorganisms). It is often used like yogurt and added to smoothies, eaten plain, or used in cooking.

How it works

Kefir contains a mix of live bacteria and yeast, plus the byproducts they create during fermentation. The main proposed benefit comes from these probiotic microorganisms, which may help support a healthy balance of bacteria in the gut.

During fermentation, the microbes break down some of the milk sugar (lactose) and produce compounds such as organic acids and certain peptides. Laboratory research suggests some of these compounds may have antimicrobial or antioxidant effects, but it is not clear how much of this matters once the drink is digested.

Kefir is also a good source of protein, calcium, and B vitamins. It is important to remember that many of the proposed mechanisms are based on test-tube and animal studies, and may not translate directly to health benefits in people.

Effectiveness

Does Kefir work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 26 uses evaluated

26 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Kefir, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 26 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Allergic rhinitis (hay fever)