Which Antibiotics Cause Diarrhea?

All antibiotics have the potential to cause diarrhea, which can range from mild to severe. Some classes of antibiotics are more likely to cause this side effect than others.

Some antibiotics that pose a high or moderate risk of diarrhea include:

• Cephalosporins, such as cefdinir and cefpodoxime
• Fluoroquinolones, such as ciprofloxacin and levofloxacin
• Macrolides, such as azithromycin, clarithromycin, erythromycin, and roxithromycin
• Penicillins, such as amoxicillin and ampicillin

Knowing which antibiotics are most likely to cause diarrhea can help you and your healthcare provider decide which one may be best for you the next time you need to treat a bacterial infection. This may be particularly important to you for practical reasons, but also if you have certain health conditions.

This article explains why antibiotics cause diarrhea and which ones are most likely to cause it. It also discusses how taking probiotics along with antibiotics can help to prevent antibiotic-associated diarrhea.

Why Antibiotics Cause Diarrhea

Your body harbors friendly bacteria on your skin and throughout your digestive tract. For the most part, these bacteria are beneficial, assisting in digesting and processing nutrients from food. They also provide a barrier to overgrowth or infection by bacteria that may cause illness.

When you have a bacterial infection such as strep throat or a urinary tract infection, your healthcare provider may prescribe an antibiotic to kill the pathogen causing the illness. But antibiotics act throughout your body and may kill both the bacteria that keep you healthy and that which causes illness.

That alters the way your intestine handles nutrients and fluids. It also changes its motility, or the way it contracts to move material through. When that happens, many people develop diarrhea.

In most cases, this diarrhea will be mild and clear up quickly once you have ended your course of antibiotics.

C. Difficile-Associated Diarrhea

In a small number of people (1% to 3% of healthy adults), a bacteria called Clostridioides difficile (C. difficile or C .diff) lives in the colon.

In a minority of those people, C. difficile may begin to multiply and take over the colon after a course of antibiotics. This can, unfortunately, result in C. diff-associated diarrhea (also called pseudomembranous colitis).

In rare cases, this may also be associated with toxic megacolon, which is a life-threatening surgical emergency.

Antibiotics Most Likely to Cause Diarrhea

While any antibiotic can result in either mild diarrhea or C. difficile colitis, some have a higher risk of doing so than others. The antibiotics formulated to kill a wide variety of bacteria (both the good and the bad) are more likely to have this effect.

Highest amount of risk:

• Lincosamides (e.g., clindamycin)
• Monobactams (e.g,. aztreonam)
• Cephalosporins (e.g., ceftriaxone, cefotaxime)
• Fluoroquinolones (e.g., ciprofloxacin, norfloxacin, ofloxacin)
• Carbapenems (e.g., doripenem, ertapenem)

Moderate amount of risk:

• Penicillins (e.g., penicillin G, ampicillin)
• Imipenem
• Macrolides (e.g., erythromycin, azithromycin)
• Sulfa-trimethoprim

Lowest risk:

• Aminoglycosides (e.g., amikacin, gentamicin, streptomycin, tobramycin)
• Metronidazole
• Nitrofurantoin

Tetracycline has shown no increased risk of diarrhea.

Probiotics for Prevention

Probiotics are naturally occurring so-called "friendly" bacteria that help promote a healthy gut. Besides those that reside in the body, probiotics can be consumed in yogurt and fermented foods, and are also widely available over the counter as supplements.

Although limited, there is research to suggest taking probiotics can help to significantly lower the risk of antibiotic-related diarrhea. Lactobacillus rhamnosus GG and Saccharomyces boulardii strains appear to be particularly effective.

The American Gastroenterology Association (AGA) 2020 clinical practice guidelines conditionally recommend the use of certain probiotic strains and combinations of strains over no or other probiotic strains in the prevention of C. difficile infection for adults and children on antibiotic treatment.

In its recommendation, the AGA notes that people concerned about potential harms, those who want to avoid the associated cost and those generally unconcerned about developing C. difficile can reasonably choose to forgo probiotics altogether.

Talk to your healthcare provider before starting probiotics or any other supplements.

Also note that probiotics supplements are not regulated with the same rigor as medications. Be sure you are buying them from a reputable retailer and look for brands that are certified by a third party, such as US Pharmacopeia.

IBD and Antibiotics

If you have inflammatory bowel disease (IBD), especially with an ostomy or a J-pouch, it is important to talk to a gastroenterologist about antibiotics.

While various antibiotics have been explored as treatments for some types of IBD or its complications, antibiotics have been also been associated with IBD flare-ups and an increased risk of C. difficile infection.

If you have IBD and are thinking of using a probiotic to repopulate your digestive system after a course of antibiotics, discuss it with your gastroenterologist first.

A Word From Verywell

A bacterial infection may need to be treated with antibiotics, and there may be no way of getting around that. The choice of antibiotics used won't be based on whether or not it has a low risk of C. difficile colitis, but rather on what is the right choice for killing the bacteria that are causing your infection.

If you have concerns about having problems with diarrhea after taking antibiotics, talk to your healthcare provider. In some cases, there may be some leeway with which antibiotic to use, but it has to be effective against the bacteria that is causing the infection.