Diarrhea is one of the most common antibiotic side effects. About 1 in 5 people who take antibiotics have loose stools, according to Mayo Clinic.
Antibiotics are medicines that kill bacteria. They're an important treatment for bacterial infections like strep throat and pneumonia, which is why doctors prescribe them to millions of Americans every year.
Usually, antibiotic-associated diarrhea is mild and it clears up after you’ve finished taking the antibiotic. But sometimes this symptom can be serious enough to make you stop taking the antibiotic and get treatment. This article will look at the causes of antibiotic-associated diarrhea, what symptoms to watch for if you take antibiotics, and how to manage this side effect.
What Is Antibiotic-Associated Diarrhea?
Antibiotic-associated diarrhea is loose, watery stools three or more times a day after taking antibiotics. These medicines can disrupt the balance of helpful ("good") bacteria and harmful ("bad") bacteria in your GI tract. When there are too many bad bacteria, they can cause symptoms like diarrhea and nausea.
Antibiotic-Associated Diarrhea Causes and Risk Factors
Certain antibiotics are more likely than others to cause diarrhea, including:
Cephalosporins like cefdinir (Omnicef) and cephalexin (Keflex)
Fluoroquinolones such as ciprofloxacin (Cipro) and levofloxacin (Levaquin)
Macrolides like clarithromycin (Biaxin) and clindamycin (Cleocin)
Penicillins such as amoxicillin (Amoxil)
Certain antibiotics, including clindamycin, fluoroquinolones, cephalosporins, and penicillins, cause a type of bacteria called Clostridioides difficile (C. diff) to multiply out of control. These bacteria release a toxin that attacks the lining of the intestines. A C. diff infection produces more severe symptoms like bloody diarrhea, weight loss, nausea, and vomiting.
Symptoms to Watch For
Loose stools usually appear within a week after you start taking the antibiotic and can last for a few days. But sometimes, you may not see any symptoms until after you've finished taking the antibiotic.
Symptoms of C. diff diarrhea include:
Severe watery diarrhea
Abdominal cramps
Fever
Pus or blood in the stools
Low-grade fever
Nausea
Appetite loss
How to Prevent Diarrhea When Taking Antibiotics
Try to use antibiotics only when you need them. Don't take these medicines for a viral illness like a cold or the flu. Antibiotics only kill bacteria; they won't work against viruses. If you have to take antibiotics to treat a bacterial infection, follow these tips to help prevent them from causing diarrhea.
Take Probiotics
Probiotics are bacteria and yeast that have positive effects on human health. They help restore the balance of good and bad bacteria in the gut, which can make them useful for preventing or helping you recover from antibiotic-associated diarrhea.
Research shows that probiotics help to prevent antibiotic-associated diarrhea in both children and adults. In a review of 33 studies comparing the effects of probiotics with placebo (inactive pills), other treatments like infant formula, and no treatment in more than 6,000 children taking antibiotics, fewer children in the probiotic group (8 percent) developed antibiotic-associated diarrhea compared to the other groups (19 percent). The authors say that probiotics can prevent one case of antibiotic-associated diarrhea for every nine children treated. High doses of probiotics were more effective at preventing diarrhea in children taking antibiotics.
An analysis of 36 studies that included 9,312 adults found that probiotics reduced antibiotic-associated diarrhea by 38 percent. Most of the reported side effects from probiotics were mild, including nausea, bloating, and indigestion.
Probiotics contain different strains of beneficial bacteria. The species with the best evidence for treating antibiotic-associated diarrhea include:
Lactobacillus
Bifidobacterium
Saccharomyces
Probiotic supplements come in tablets, powders, and capsules. You can also get probiotics from foods like yogurt, sauerkraut, and kombucha. Follow the directions when you take supplements. Some products are easier for your body to absorb on an empty stomach. Others might cause stomach upset if you don't take them with food. If you have a weakened immune system because of a chronic condition or medication you take, ask your doctor before using probiotic supplements.
Make Dietary Changes
Diarrhea can cause fluid loss and dehydration. To replenish fluids, drink more clear liquids (water, broth) and drinks that contain electrolytes, such as a sports drink or oral rehydration solution. Avoid drinks that are high in sugar or that contain alcohol or caffeine, which can dehydrate you even more.
While there's no specific diet for diarrhea, it's best to eat foods that are gentle on your stomach, like bananas, rice, baked potato, toast, or crackers. Foods that contain probiotics, like Greek yogurt, can help to reset the correct balance of good-to-bad bacteria in your gut.
Avoid these foods, which might make diarrhea worse:
Dairy products like milk, ice cream, and cheese
Fatty foods such as burgers and fried chicken
Spicy foods
Sugary foods like cookies and candy
High-fiber foods such as whole wheat, bran, and fruit with skins on (apples, pears)
Managing Diarrhea When You're On Antibiotics
Mild diarrhea should clear up within a few days after you finish taking antibiotics. If it's severe, your doctor might recommend stopping antibiotics until the diarrhea improves. C. diff diarrhea can take longer to clear up, and it may come back after you treat it.
Immediate Steps to Take
Mild diarrhea is usually nothing to worry about. Loose bowel movements should stop within a few days.
Drink extra water and other clear fluids to prevent dehydration. Add a sports drink or other rehydration solution to replace lost electrolytes. Eat a bland diet and avoid foods like dairy and high-fiber foods, which can worsen diarrhea.
Don't take an over-the-counter anti-diarrhea medicine like loperamide (Imodium) or bismuth subsalicylate (Pepto-Bismol) without first asking your doctor. These medicines could make it harder for your body to remove harmful bacteria.
When to Call a Doctor
Call your doctor if you've been taking antibiotics and you have:
More than five loose stools a day
A fever
Pain or tenderness in your belly
Blood or pus in your stool
Signs of dehydration, which include a very dry mouth, little or no urination, dizziness, or weakness
To manage severe diarrhea, stop taking the antibiotic that caused it. Your doctor may put you on an antibiotic like fidaxomicin (Dificid) or vancomycin (Firvanq) to treat a C. diff infection. In the rare but very serious situation when antibiotics don't work and the infection becomes life-threatening, surgery may be performed to remove the affected portion of the colon.
The Takeaway
Antibiotic-associated diarrhea is watery stools caused by taking an antibiotic. Most of the time the diarrhea is mild and improves within a few days, but some people may develop a C. diff infection.
To help prevent antibiotic-associated diarrhea, take antibiotics only when absolutely necessary to treat a bacterial infection, and eat foods rich in probiotics or take a supplement.
Manage diarrhea by getting plenty of fluids and electrolytes, and eating a bland diet until this symptom resolves.
Stephanie Young Moss, PharmD, has worked in pharmacy, community outreach, regulatory compliance, managed care, and health economics and outcomes research. Dr. Young Moss is the owner of Integrative Pharmacy Outcomes and Consulting, which focuses on educating underserved communities on ways to reduce and prevent health disparities. She uses her platform to educate families on ways to decrease and eliminate health disparities by incorporating wellness and mental health techniques.
Young Moss is the creator of the websites DrStephanieYoMo.com and MenopauseInColor.com, providing practical health and wellness tips and resources for women experiencing perimenopause and menopause. She has over 100,000 people in her social media communities. She has also contributed to Pharmacy Times and shared her views on international and national podcasts and local television news.
She has served on various boards for organizations that focus on health equity, decreasing implicit bias, addressing social determinants of health, and empowering communities to advocate for their health. She has also been on the boards for the Minority Health Coalition of Marion County and Eskenazi Health Center, for which she was the clinical quality committee chair and board secretary and is currently the board treasurer. She is a board member for Community Action of Greater Indianapolis.
Stephanie Watson is a freelance health writer who has contributed to WebMD, AARP.org, BabyCenter, Forbes Health, Fortune Well, Time, Self, Arthritis Today, Greatist, Healthgrades, and HealthCentral. Previously, she was the executive editor of Harvard Women’s Health Watch and Mount Sinai’s Focus on Healthy Aging. She has also written more than 30 young adult books on subjects ranging from celebrity biographies to brain injuries in football.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
Antibiotic-Associated Diarrhea. Mayo Clinic. August 11, 2021.
Guo Q et al. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Children. Cochrane. April 30, 2019.
Wanqian L et al. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Adults: A Meta-Analysis of Randomized Placebo-Controlled Trials. Journal of Clinical Gastroenterology. July 2021.
Blaabjerg S et al. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Outpatients—A Systematic Review and Meta-Analysis. Antibiotics. 2017.
Antibiotic-Associated Diarrhea. Mayo Clinic. August 11, 2021.
What to Eat When You Have Diarrhea. Cleveland Clinic. June 16, 2023.
How to Prevent Diarrhea While You Take Antibiotics. Cleveland Clinic. January 24, 2020.
