Kefir is a creamy and tart probiotic drink that's made by adding kefir grains to milk and allowing it to ferment. The grains contain bacteria and yeast.

Kefir grains resemble cooked cauliflower. The bacteria and yeast they contain depend on where the kefir is made. Lactobacillus lactis, Lactobacillus casei, and other Lactobacillus species may be present in kefir. Many of these species can survive traveling through the stomach to the intestinal tract.

People use kefir for hay fever, diarrhea from antibiotics, athletic performance, constipation, Crohn disease, diabetes, high cholesterol, obesity, osteoporosis, and many other conditions, but there is no good scientific evidence to support these uses.

Don't confuse kefir with other fermented dairy products, including fermented milk and yogurt. These are not the same.
When taken by mouth: Kefir is possibly safe when used for up to 12 weeks. It's usually well-tolerated. Side effects might include bloating, nausea, stomach cramps, diarrhea, and constipation. These symptoms usually go away after continued use.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn't enough reliable information to know if kefir is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: Kefir is possibly safe for children between the ages of 1 and 5 years when taken by mouth for up to 10 days.

AIDS and other conditions that weaken the immune system: Kefir contains actively growing bacteria and yeast. People with a weakened immune system might be more likely to develop infections from these bacteria or yeast.

Colon cancer: In people undergoing chemotherapy for colon cancer, kefir might increase side effects such as stomach and intestinal problems, mouth sores, drowsiness, sweats, and hair loss.


There is interest in using kefir for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.
Likely effective Effectiveness definitions
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Dosing & administration

Kefir is most often used by adults in doses of 400-500 mL by mouth daily for up to 4 weeks. Lower doses of 100-180 mL daily have been used for up to 12 weeks. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Interactions with pharmaceuticals

Disulfiram (Antabuse)

Interaction Rating=Minor Be watchful with this combination.

Kefir might contain alcohol. The body breaks down alcohol to get rid of it. Disulfiram decreases the break-down of alcohol. Taking kefir along with disulfiram can cause a pounding headache, vomiting, flushing, and other unpleasant reactions. Don't drink any alcohol if you are taking disulfiram.

Medications that decrease the immune system (Immunosuppressants)

Interaction Rating=Moderate Be cautious with this combination.

Kefir contains live bacteria and yeast. The immune system usually controls bacteria and yeast in the body to prevent infections. Taking kefir along with medications that decrease the immune system might increase the chances of getting sick from bacteria and yeast.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods. has licensed monographs from TRC Healthcare.
This monograph was last reviewed on 31/05/2023 10:00:00 and last updated on 14/11/2014 17:47:44. Monographs are reviewed and/or updated multiple times per month and at least once per year.
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