Side effects and risks
Some live microorganisms have a long history of use as probiotics without
causing illness in people. Probiotics' safety has not been thoroughly studied
scientifically, however. More information is especially needed on how safe they
are for young children, elderly people, and people with compromised immune
Probiotics' side effects, if they occur, tend to be mild and digestive (such
as gas or bloating). More serious effects have been seen in some people.
Probiotics might theoretically cause infections that need to be treated with
antibiotics, especially in people with underlying health conditions. They could
also cause unhealthy metabolic activities, too much stimulation of the immune
system, or gene transfer (insertion of genetic material into a cell).
Probiotic products taken by mouth as a dietary supplement are
manufactured and regulated as foods, not drugs.
Some other points to consider
- If you are thinking about using a probiotic product as CAM, consult your
health care provider first. No CAM therapy should be used in place of
conventional medical care or to delay seeking that care.
- Effects from one
species or strain of probiotics do not necessarily hold true for others, or even
for different preparations of the same species or strain.
- If you use a probiotic
product and experience an effect that concerns you, contact your health care
- You can locate research reports in peer-reviewed journals on
probiotics' effectiveness and safety through the resources PubMed and CAM on
NCCAM-sponsored research on probiotics
Among recent NCCAM-sponsored research
are the following projects:
- Investigators at Tulane University School of Public Health and Tropical
Medicine are studying the effectiveness of selected probiotic agents to treat
diarrhea in undernourished children in a developing country.
- At the Mayo Clinic
College of Medicine, researchers have been examining probiotics for possibly
decreasing the levels of certain substances in the urine that can cause problems
such as kidney stones.
- A team at Tufts-New England Medical Center is studying
probiotics for treating an antibiotic-resistant type of bacteria that causes
severe infections in people who are hospitalized, live in nursing homes, or have
weakened immune systems.