Dynamic Duo: Antibiotics and Probiotics

colorful photograph of antibiotics
Photograph of antibiotics, courtesy of sparktography via Creative Commons license.

When your cold or flu virus turns into a bacterial infection, like a severe sinus infection, taking antibiotics can seem like a miracle. You often start feeling better after just a day or two, and you’re no longer contagious after about three days.

Antibiotics work by killing bacteria or by stopping bacteria from multiplying. Each type of antibiotics affects different bacteria in different ways, although broad-spectrum antibiotics are used to treat a wide range of infections. Antibiotics quickly make you feel better because the drug kills the majority of the targeted bacteria very quickly.

However antibiotics also kill beneficial bacteria and induce negative side effects -- most commonly diarrhea, upset stomach, and vaginal yeast infection. For instance, antibiotics cause about one out of three people to get diarrhea by disrupting the balance of the intestinal flora, a collection of bacteria and other microorganisms in the digestive tract. This can result in an overgrowth of the Clostridium difficile bacteria that causes diarrhea. Similarly, antibiotics can disrupt the vaginal flora and cause an overgrowth of Candida yeasts to cause a yeast infection.

Probiotics are live bacteria, yeasts and other microbes intended to maintain or restore the supply of beneficial bacteria in the body, particularly the stomach and intestines. Probiotics are found naturally in certain foods, including yogurt, aged cheeses, kefir, miso, tempeh, and fermented cabbage. Dietary supplements are another common source of probiotics.

Although probiotics have been widely promoted as a way to keep your body in balance, scientific evidence for these claims have been weakened by the small size of most research studies. However, the use of probiotics to reduce antibiotic-induced side effects is now becoming more widely accepted by the medical profession.


A recent study published in the Journal of the American Medical Association supports taking probiotics with antibiotics. A team of researchers from southern California combined and analyzed the results of 63 randomized controlled trials of probiotics for the prevention or treatment of antibiotic-associated diarrhea. The 11811 men and women included in this large combined study took a placebo or probiotics supplement along with their antibiotics. The people who took the probiotics were 42% less likely to develop diarrhea than those taking the placebo. This pooled evidence strongly suggests that probiotics can help populations of beneficial bacteria recover and more quickly restore balance in the intestines.

However, further research is needed to determine which probiotics are the most effective at preventing and treating antibiotic-associated side effects, as well as determine the optimal dose of the probiotics. Research is also needed to identify which antibiotics are most likely to induce adverse effects. Hopefully these further studies are underway.

Of course it is also important to limit your use of antibiotics, using them only for bacterial infections when necessary. Common cold and flu viruses don’t respond to antibiotics anyway.