What to Know About Antibiotic-Induced Diarrhea

• Antibiotics work by killing bacteria, but they also eliminate beneficial microbes in the gut, disrupting the microbial balance that supports normal digestion. Broad-spectrum antibiotics that target many bacterial species carry greater risk than narrower, more targeted options.
• Loose stools linked to antibiotic use typically appear within about a week of starting treatment. If diarrhea develops, contact your doctor before discontinuing the medication—stopping early may allow the infection to return.
• Managing antibiotic-related diarrhea involves consuming easily digestible foods, maintaining hydration with electrolyte-containing beverages, and incorporating probiotics. Foods high in fat, spice, or caffeine should be limited during this time.
• The best defense against antibiotic-induced diarrhea centers on using the most appropriate antibiotic for your specific infection and supporting gut health through probiotic foods and supplements both during and after treatment.

Infections often land patients in the doctor's office with a prescription for antibiotics. While these drugs are highly effective at eliminating harmful bacteria, they bring unwanted side effects—and one of the most bothersome is diarrhea.

Antibiotic-induced diarrhea is extremely common, and fortunately, it usually resolves once you finish your medication course. Still, while taking antibiotics, you may find yourself making frequent trips to the bathroom and wondering whether the side effect warrants stopping treatment early or if anything can ease the discomfort.

This guide explains why antibiotics trigger diarrhea, which medications pose the greatest risk, and what steps you can take to manage or prevent the problem.

Why antibiotics cause diarrhea

Yes—loose stools are among the most frequently reported antibiotic side effects. Research indicates that between 5% and 35% of patients using antibiotics experience antibiotic-associated diarrhea.

The mechanism is straightforward: antibiotics destroy bacteria indiscriminately, killing both disease-causing organisms and the beneficial microbes that live in your intestines. This disruption of the gut's natural microbial ecosystem prevents your digestive system from processing stool normally, resulting in loose or watery output.

Not all antibiotics carry equal risk. When physicians don't know the exact cause of an infection, they often prescribe "broad-spectrum" antibiotics—drugs that kill a wide range of bacterial species. These broad-acting medications are more likely to wipe out protective gut bacteria than narrower, targeted antibiotics designed to fight specific pathogens. As Christina M. Madison, Pharm.D., FCCP, explains, "Different classes of antibiotics treat different types of bacteria." She adds, "When we are unsure what the infection is being caused by, we typically use what’s called 'empiric' therapy with a 'broad spectrum' antibiotic."

According to the Mayo Clinic, antibiotic-associated diarrhea typically emerges about one week after the first dose. If you develop diarrhea during antibiotic treatment, notify your healthcare provider about the frequency and severity rather than discontinuing the medication on your own. Stopping antibiotics prematurely can allow your infection to worsen or return.

Antibiotic types most likely to cause diarrhea

Most antibiotic classes carry some diarrhea risk, but the level varies. Narrowly targeted antibiotics that attack only one or two bacterial species pose lower risk than broad-spectrum drugs, which disrupt a wider swath of your microbiome.

As Dr. Minesh Amin explains, "We can never select an antibiotic with the intent to try and avoid antibiotic-induced diarrhea. The choice of antibiotic is always based on the greatest likelihood of eradicating the active infection."

The antibiotic classes most strongly linked to diarrhea include:

Lincosamides (notably clindamycin) carry the highest risk according to meta-analyses of over 2 million adverse reaction reports.

Beta-lactams such as amoxicillin, penicillin, ampicillin, and cephalosporins (including cephalexin, cefpodoxime, and cefdinir) frequently trigger loose stools.

Macrolides like erythromycin, clarithromycin, and azithromycin are common culprits, though azithromycin appears slightly less disruptive to gut bacteria than other drugs in this class.

Fluoroquinolones including ciprofloxacin and levofloxacin are frequently prescribed for urinary and respiratory infections and commonly cause diarrhea.

C. difficile infection risk from antibiotics

Repeated antibiotic courses can allow a dangerous bacterium called Clostridioides difficile (C. difficile or C. diff) to proliferate unchecked in the colon. "When it is allowed to overgrow, C. diff releases a toxin that damages the lining of our gut," Dr. Pepin explains. "The result of this is an infection that causes severe diarrhea and inflammation."

Unlike garden-variety antibiotic-induced diarrhea, C. difficile infection is highly contagious and poses serious health risks, particularly among hospitalized patients. Mortality is significant in vulnerable populations—roughly 9% of adults aged 65 and older die within 30 days of a C. difficile diagnosis.

Scrupulous hand hygiene is essential for preventing transmission. If you suspect C. difficile infection, seek immediate medical attention.

Recognizing symptoms of antibiotic-related diarrhea

Most antibiotic-related diarrhea is mild, presenting as:

• Loose or watery stools • Frequent bowel movements (three or more times daily)

C. difficile infection produces more severe symptoms:

• Profuse, often uncontrollable watery diarrhea • Frequent bowel movements • Abdominal pain and cramping • Nausea • Reduced appetite • Fever

Seek immediate medical evaluation if you develop symptoms suggestive of C. difficile infection.

Dietary recommendations for managing antibiotic-related diarrhea

Dietary adjustments and hydration form the foundation of managing antibiotic-related diarrhea.

Eat starchy, easily digested foods. Bland carbohydrates are gentler on a compromised digestive tract. The BRAT diet—bananas, rice, applesauce, and toast—is a commonly recommended starting point. As Dr. Minesh Amin notes, "One of the most common recommendations when experiencing antibiotic-induced diarrhea is the BRAT diet. This includes bananas, rice, applesauce, and toast."

Include probiotic-rich foods. Yogurt with live active cultures helps replenish beneficial bacteria that antibiotics have eliminated. Plain yogurt offers added benefits: it contains probiotics, soothes intestinal inflammation with its cooling effect, and delivers essential nutrients including calcium, B-12, and vitamin D. Always check the label to confirm the yogurt contains live active cultures. Dr. Amin also emphasizes that "yogurt is packed with essential nutrients such as calcium, B-12, and vitamin D."

Prioritize hydration with electrolytes. Watery diarrhea causes rapid fluid loss, and with it, essential electrolytes like sodium, potassium, and magnesium. Plain water is insufficient—electrolyte-containing beverages such as Pedialyte, Gatorade, Powerade, and broths are absorbed more efficiently and replace lost minerals more effectively. According to Dr. Amin, "Electrolyte solutions in general are far superior to water when a person has diarrhea because the electrolytes allow quicker absorption of the water into the body."

Avoid problematic foods. Red meat, spicy foods, greasy preparations, caffeine, and alcohol all stimulate the digestive tract and worsen diarrhea. Eliminating these temporarily allows your gut to settle.

Self-care strategies for antibiotic-induced diarrhea

Antibiotic-associated diarrhea typically resolves on its own within days of finishing your medication. While waiting for it to clear, several self-care strategies can ease discomfort:

• Consume bland, low-fiber, starchy foods until symptoms improve • Avoid fried and spicy preparations • Skip alcohol and caffeine while on antibiotics • Use probiotic supplements to restore gut bacteria balance • Drink adequate water, fruit juices, and electrolyte beverages • Ask your doctor about over-the-counter anti-diarrheal medications like loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol)

Research identifies two probiotic strains as particularly effective for antibiotic-induced diarrhea: Lactobacillus rhamnosus GG (LGG) and Saccharomyces boulardii. Both are readily available in oral supplement form.

As Dr. Madison says, "One to two loose stools per day is common from antibiotic therapy. If you are experiencing significant side effects from your medication therapy, you should reach out to the prescribing provider before discontinuing therapy."

Call your healthcare provider right away if you experience additional symptoms such as weakness, fever, or loss of appetite. As Dr. Pepin explains, "A doctor can do a stool sample to test for C. diff and treat it quickly."

Preventing diarrhea during antibiotic treatment

Prevention begins with judicious antibiotic use. Only take antibiotics when prescribed for a confirmed or suspected bacterial infection—these drugs do not work against viruses like the common cold or influenza.

Beyond that, prevention overlaps substantially with treatment strategies:

Use the most targeted antibiotic available. Request or discuss with your doctor whether a narrowly targeted antibiotic is suitable for your infection rather than a broad-spectrum option. Targeted drugs spare more of your beneficial gut bacteria.

Start probiotics during treatment. Introducing good bacteria through probiotic supplements or foods during your antibiotic course may help prevent diarrhea or reduce its severity.

Continue probiotic support after finishing antibiotics. Eating yogurt with live active cultures or taking oral probiotic supplements for approximately one week after completing your antibiotic course can prevent post-treatment diarrhea and help restore your microbiome more completely.

What about constipation?

Constipation is less consistently linked to antibiotics than diarrhea is. When it shows up alongside a course of antibiotics, it's more often related to other factors — reduced activity while unwell, changes in eating or fluid intake, or other medications you're taking at the same time — though disruption to gut bacteria can occasionally play a role here too, since gut flora also has a hand in normal motility. If constipation is severe, persistent, or paired with significant abdominal pain, it's worth mentioning to your prescriber rather than assuming it will resolve on its own.