Why Do Probiotics Make Me Sick?

Probiotics are good bacteria that exist naturally throughout your body, particularly in your intestines. These healthy microorganisms maintain a reciprocal relationship, gaining nourishment from your body, while promoting the proper balance of good and bad bacteria. Although probiotics are naturally occurring, side effects may occur that make you feel sick. Side effects are generally minimal and mild, however long-term effects of supplemental probiotics remain unknown as of 2011.


Probiotics are live microorganisms that are similar to the microorganisms living naturally in your intestines. Microflora occur naturally in your gut, including microorganisms such as bacteria, fungi and yeasts. The healthy bacteria normally make up about 85 to 90 percent of the bacteria in your gut, with bad bacteria comprising the remainder. Use of antibiotics kills the good bacteria along with the bad. While probiotics provide the opportunity to restore the balance of good bacteria, you are also introducing new bacteria to your system, which may yield side effects.


Research shows probiotics are effective supplements for a host of conditions, restoring good bacteria to the body while minimizing the harmful effects of the bad bacteria, yeasts and fungi. The National Center for Complementary and Alternative Medicine indicates research is ongoing regarding the efficacy of probiotics for use in treating urinary tract infections, irritable bowel syndrome, bacterial vaginosis and yeast infections, inflammatory bowel disease and periodontal infections. Research is also promising for use of probiotics to treat skin infections and eczema. MayoClinic.com suggests more evidence is required on use of probiotics, but research as of 2011 is encouraging.

Common Side Effects

Probiotics are living microorganisms, carrying with them inherent unpredictability in how they might interact with you as their host and the other indigenous microbiotica presently in your gastrointestinal tract. Mild symptoms are experienced by some, particularly if probiotics are not introduced incrementally, including gastrointestinal upset, such as gas, abdominal pain and bloating. For some, inactive ingredients in the probiotic supplement, such as plant or mineral materials, may not be tolerated by users. You may also experience an allergic reaction to probiotics, making you feel ill.

Illness from Probiotics

Theoretically probiotics could make you sick, according to the National Center for Complementary and Alternative Medicine, or NCMA. Probiotic supplements introduce bacteria into your system, which could contribute to illness, particularly if you have a compromised immune system. The NCMA also warns that probiotics may also prompt unhealthy metabolic activities, gene transfer or overstimulation of the immune system. Probiotics are not recommended for use if you have severe pancreatitis as they may increase your chances of mortality from this illness, according to a study published in the "Lancet" in February 2008.

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