Kefir's disadvantages include its saturated fat content, relatively high calorie density and heavy sugar concentration. Kefir also interacts poorly with certain medications. The bacteria, yeast and probiotics found in kefir can also potentially cause digestion problems, such as constipation, intestinal cramping and stomach pain.
Due to the bacteria created during the fermentation process, kefir may cause illnesses and infections in people with compromised immune systems. It also aggravates symptoms of bowel disorders, like Crohn's Disease and Irritable Bowel Syndrome.
Potential side effects are another disadvantage of kefir. The bacteria and probiotics found in kefir often induce several unpleasant side effects, especially when users first begin drinking kefir. Negative side effects include nausea, abdominal pain, headaches, diarrhea, stomach discomfort, bloating and gas. Some people report skin problems like acne or boils.
Kefir also causes dangerous blood pressure spikes in people who take antidepressants. It interferes with most immunosuppresant medications, including basiliximab, azathioprine, tacrolimus and prednisone. Research suggests that kefir may trigger migraines in some patients.
Additionally, there is no concrete proof that kefir is a suitable treatment option for any medical condition. Despite numerous claims, there is no evidence that kefir improves high cholesterol, treats antibiotic-induced diarrhea, cures lactose intolerance or alleviates mouth sores.