Drug & supplement interaction

Kefir + Durvalumab

Durvalumab brand name: Imfinzi.

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

Kefir has a moderate interaction with Durvalumab. Theoretically, kefir might increase the risk of bacterial and yeast infections in patients taking immunosuppressants.

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

Kefir and Durvalumab

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

Moderate

IMMUNOSUPPRESSANTS

Why this applies to Durvalumab

Durvalumab falls under IMMUNOSUPPRESSANTS — the group Kefir interacts with.

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

Kefir contains actively growing bacteria and yeast.
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 kefir with Imfinzi (durvalumab). This isn't a case where kefir changes how the drug is broken down or how well it fights your cancer. Durvalumab is an immunotherapy antibody, and kefir won't make it stronger or weaker. The concern is different: kefir is a living food, full of active bacteria and yeast, and some cancer treatments can lower your body's ability to keep those microbes in check.

The worry here is mostly theoretical and based on lab-type reasoning, not strong human studies, so I don't want you to panic. Still, if your immune system or blood counts are running low during treatment, it's worth a quick chat with your oncology team or pharmacist before adding daily kefir.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. 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
  2. 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
  3. Rimada PS, Abraham AG. Polysaccharide production by kefir grains during whey fermentation. J Dairy Res 2001;68:653-61. PubMed
  4. 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.

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

Kefir Also Interacts With Other Medications

Kefir has 120 moderate, 1 minor known drug interactions in our database — the Durvalumab one above is one of them. If you take anything else, check it against the full list below.

Moderate 120 Minor 1 No known interaction 2,709 (incl. Durvalumab)
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.

Everything else you take

See Every Supplement That Interacts With Durvalumab

This page covers Kefir only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Durvalumab page lists 54 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Active Hexose Correlated Compound (ahcc) (moderate), Alfalfa (moderate), American Ginseng (moderate), Andrographis (moderate) and Ashwagandha (moderate).

By severity: 52 moderate · 2 minor.

From our pharmacist’s overview on the Durvalumab page

“Nearly everything on this page interacts with durvalumab (Imfinzi) for the same underlying reason, immune stimulation. Durvalumab is a cancer immunotherapy, and because the treatment works through the immune system itself, supplements that push immune activity in their own direction (echinacea, ashwagandha, astragalus, and dozens of si…”

Reviewed by 2 · Jul 18, 2026

Open the Durvalumab 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. Your product may carry other ingredients that interact with Durvalumab too, on top of Kefir — 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 Kefir and Durvalumab 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

#1,064 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Durvalumab
Steady interest

#2,208 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 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.

Read the full Kefir monograph & all interactions
Medication

About Durvalumab Injection

What Is Durvalumab Injection Used For?

Brand name: Imfinzi

Imfinzi is used to treat a wide range of cancers in adults. For lung cancer, it is approved for resectable non-small cell lung cancer (given before and after surgery), unresectable Stage III non-small cell lung cancer (after chemoradiation), metastatic non-small cell lung cancer, limited-stage small cell lung cancer (after chemoradiation), and extensive-stage small cell lung cancer.

Beyond lung cancer, Imfinzi is also approved for locally advanced or metastatic biliary tract cancer (cancers of the bile ducts and gallbladder), unresectable hepatocellular carcinoma (liver cancer), mismatch repair deficient (dMMR) advanced or recurrent endometrial cancer, BCG-naive high-risk non-muscle-invasive bladder cancer, muscle-invasive bladder cancer, and resectable gastric or gastroesophageal junction adenocarcinoma (stomach cancer at the junction with the esophagus). Most of these uses involve Imfinzi given alongside other chemotherapy drugs.

See full Durvalumab Injection 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
120Moderate
1Minor
2,708No known interaction
120 Moderate 1 Minor 2,708 No interaction
Moderate

120 interactions

Showing 60 of 120 moderate interactions — see all 120 on the Kefir page.

Minor

1 interaction

No interaction 2,708 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 2,708 medications checked with no known interaction — see the full Kefir list.

See the full Kefir interactions page
See every supplement checked against Durvalumab, 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
Kefir monograph › Uses, safety, and every drug interaction in one place Durvalumab supplement interactions › Every supplement checked against Durvalumab, ranked by severity Durvalumab Injection 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 Kefir and Durvalumab Together: Common Questions

Can you take Kefir with Durvalumab?
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 Kefir and Durvalumab 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 Durvalumab and Kefir?

Our pharmacists answer your medication & supplement questions — free.

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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.