Supplements containing probiotics--"friendly" bacteria that promote digestive health and immunity--are increasingly popular among health-conscious consumers. According to the National Center for Complementary and Alternative Medicine (NCCAM), sales of probiotics nearly tripled between 1994 and 2003. NCCAM notes that probiotics show promise as a treatment for diarrhea, irritable bowel syndrome, urinary tract infections and pediatric eczema. Nevertheless, like all supplements, probiotics are associated with some drawbacks.
Medline Plus, a service of the National Institutes of Health, notes that many of the uses for L. acidophilus--the world's most popular probiotic--are unproven. While good scientific evidence supports the use of acidophilus as a treatment for bacterial vaginosis, there have not been enough large-scale, double-blind clinical trials to fully establish the notion that probiotics can treat other illnesses.
Gastrointestinal Side Effects
According to the National Institutes of Health, probiotics sometimes cause mild gas or stomach discomfort. However, this side effect usually diminishes with continued use. This side effect is rarely seen in people taking moderately low doses of probiotics.
Possibility of Infection
According to the National Institutes of Health, people with severely compromised immune systems may experience a systemic infection after taking probiotics. This life-threatening side effect is extremely rare. It has only been documented in people whose immune systems have been compromised by AIDS, chemotherapy drugs or immunosuppressants.