Millions of friendly bacteria live in our intestines. They’re essential to digestion. But diarrhea can throw the microbes in your gut off balance, and vice versa. Probiotics, which are doses of helpful bacteria or yeasts, may help get things back on track.
One source of probiotics you know about is yogurt, which is made by adding bacteria to milk. The same microbes may help keep your intestines healthy. There are dozens of other kinds that may have health benefits, too.
First, your health care provider will look at your anal area, perhaps by inserting a lubricated gloved finger or an anoscope (a hollow, lighted tube for viewing the lower few inches of the rectum) or a proctoscope (which works like an anoscope, but provides a more thorough rectal exam).
More procedures may be needed to identify internal hemorrhoids or rule out other ailments that frequently cause anal bleeding, such as anal fissure, colitis, Crohn's disease, and colorectal cancer.
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Not all probiotics help diarrhea. And probiotics help only certain types of diarrhea. So which ones may help and when?
Kids and Diarrhea
Some of the best proof that probiotics work comes from studies of diarrhea in children, especially cases caused by rotavirus.
Probiotics can cut bouts of infectious diarrhea by half a day to about 2 days.
Some research shows that the bacteria strains most likely to help are Lactobacillus rhamnosus, Lactobacillus reuteri, and Saccharomyces boulardii, although other strains might also be useful. A mix of a few different probiotics may also help treat this type of diarrhea.
Diarrhea From Antibiotics
Antibiotics kill the bad germs in your body that make you sick, but they also kill the good bacteria. This can disrupt the normal balance in your intestines, leading to diarrhea. It’s common for 10% to 30% of people taking these medicines.
Studies of both children and adults have shown that probiotics taken before and with antibiotics can lower the risk of diarrhea. Saccharomyces boulardii and Lactobacillus can be effective.
Travelers often come down with diarrhea caused by bad food or water. Cases can last a month or longer.
There’s no hard proof probiotics work for this condition. A 2007 report found they helped travelers avoid this kind of diarrhea. But other studies have shown that they don’t really help. The strongest evidence pointed to benefits from S. boulardii, Lactobacillus acidophilus, and Bifidobacteria bifidum.
Diarrhea Caused By C. difficile
Infection with C. difficile bacteria causes severe and sometimes life-threatening diarrhea and inflammation in the colon, called colitis. Probiotics may keep you from getting this germ. And there’s some evidence they can stop the condition from coming back. That’s important, since repeat infections become hard to control.
Scientists have studied Saccharomyces boulardii the most against this type of bacteria. In one large study, patients with recurrent diarrhea took either a probiotic or a placebo. Only 9 out of 26 people in the probiotics group had more diarrhea. In the placebo group, 22 out of 34 had diarrhea that came back. Lactobacillus plantarum may also help this type of diarrhea.