What to do when your antibiotic gives you diarrhea?

October 13, 2025 •

4 min read

About 1 in 5 people who take antibiotics will develop antibiotic-associated diarrhea (AAD), which is defined as loose, watery stools occurring three or more times a day [1.2.1]. Knowing what to do when your antibiotic gives you diarrhea is key to managing symptoms and preventing complications.

Quick Summary

Antibiotic-associated diarrhea is a common side effect of medication. Management involves staying hydrated, adjusting your diet, considering probiotics, and monitoring for severe symptoms that require medical attention, such as a C. diff infection.

Key Points

Prevalence: Roughly 1 in 5 people who take antibiotics experience diarrhea as a side effect [1.2.1].
Primary Cause: Antibiotics disrupt the natural balance of good and bad bacteria in the gut, leading to digestive issues [1.5.6].
Initial Management: Focus on staying hydrated with water and electrolyte-rich fluids and switch to a bland, low-fiber diet [1.3.1, 1.5.2].
Probiotics are Helpful: Taking probiotics like Saccharomyces boulardii or Lactobacillus species can help prevent and reduce the severity of antibiotic-associated diarrhea [1.4.2, 1.4.6].
Beware of C. diff: Severe, watery diarrhea accompanied by fever and abdominal pain could indicate a serious C. difficile infection that requires immediate medical care [1.6.5, 1.7.5].
Consult a Doctor: Do not take anti-diarrheal medications like Imodium without a doctor's approval, as they can worsen a C. diff infection [1.9.1, 1.9.4].
When to Call for Help: Contact a healthcare provider if you have severe symptoms like high fever, blood in the stool, or signs of dehydration [1.6.2, 1.6.3].

Understanding Why Antibiotics Cause Diarrhea

Antibiotics are powerful medications designed to kill harmful bacteria causing infections [1.5.6]. However, they can be indiscriminate, also eliminating the beneficial bacteria that reside in your gut [1.5.6]. This disruption of the natural gut microbiome can lead to digestive upset, most commonly diarrhea [1.2.2]. The incidence rate for adults is between 5% and 25% [1.2.3]. The diarrhea is typically mild and resolves after you finish the antibiotic course [1.6.3]. However, in some cases, the imbalance allows opportunistic and harmful bacteria, such as Clostridioides difficile (C. diff), to multiply and cause a more severe infection [1.2.3, 1.3.5]. Certain antibiotics, including clindamycin, cephalosporins, and penicillins, are more frequently associated with this side effect [1.3.6, 1.8.2].

Immediate Steps to Take

If you experience mild diarrhea, the primary goals are to manage symptoms and prevent dehydration.

Stay Hydrated: Diarrhea leads to a loss of fluids and electrolytes. It's crucial to replenish these by drinking plenty of water, broths, or oral rehydration solutions [1.3.1, 1.3.4]. Avoid sugary drinks, caffeine, and alcohol, as they can worsen symptoms [1.3.1].
Adjust Your Diet: Opt for bland, low-fiber foods that are easy to digest. The BRAT diet (bananas, rice, applesauce, and toast) is often recommended [1.5.2]. Also include peeled and boiled potatoes, plain noodles, and lean proteins like chicken or fish [1.5.2]. Temporarily avoid dairy products (except for probiotic-rich yogurt), fatty foods, spicy foods, and high-fiber foods [1.5.2, 1.5.3].
Continue Your Medication: Do not stop taking your antibiotic without consulting your doctor first. Stopping prematurely can lead to incomplete treatment of your original infection.
Consider Probiotics: Probiotics are beneficial live bacteria that can help restore balance to your gut [1.4.5]. Studies suggest that taking probiotics, such as Lactobacillus rhamnosus and Saccharomyces boulardii, during antibiotic treatment can reduce the risk of developing diarrhea [1.4.2, 1.4.6]. They are available in supplements and in fermented foods like yogurt with "live and active cultures" [1.3.3, 1.5.4]. It is generally recommended to take probiotics a few hours apart from your antibiotic dose [1.5.6].

The Risk of C. difficile Infection

While most cases of AAD are mild, a small percentage are caused by an overgrowth of Clostridioides difficile [1.2.4]. This bacterium produces toxins that can cause severe, watery diarrhea (10 to 15 times a day), abdominal cramping, fever, nausea, and loss of appetite [1.6.5, 1.7.5]. C. diff is a serious condition that requires immediate medical attention and can lead to life-threatening complications like severe dehydration, toxic megacolon, and sepsis [1.7.2, 1.7.4].

Risk factors for C. diff infection include being over 65, having a weakened immune system, and a recent or long stay in a hospital or nursing home [1.7.2, 1.6.3]. If you suspect a C. diff infection, it is crucial not to take anti-diarrheal medications like loperamide (Imodium), as they can prevent your body from expelling the toxins and worsen the condition [1.9.1, 1.9.4]. Treatment for C. diff involves stopping the initial antibiotic and starting a different one, such as vancomycin or fidaxomicin, that specifically targets C. diff [1.3.5, 1.6.6].

Management Strategy Comparison


Strategy	Mechanism of Action	Best For	Onset of Action	Precautions
Dietary Management (BRAT)	Provides bland, low-fiber foods that are easy on the digestive system and help firm up stool [1.5.2].	Mild, uncomplicated diarrhea.	Within a day or two.	A short-term solution; lacks a full range of nutrients.
Probiotics	Restore beneficial bacteria in the gut, helping to re-establish a healthy microbiome balance [1.4.1, 1.4.5].	Prevention and management of mild to moderate AAD [1.4.2].	Can take several days to show effects.	Generally safe, but those with weakened immune systems should consult a doctor [1.3.3, 1.4.4].
Anti-diarrheal Meds (Loperamide)	Slows down gut motility to reduce the frequency of bowel movements [1.9.1].	Mild AAD only after consulting a doctor.	Within a few hours.	Must not be used if C. diff is suspected or if you have a fever or bloody stool, as it can trap toxins [1.9.1, 1.9.4, 1.9.5].

When to See a Doctor

You should contact your healthcare provider if you experience any of the following symptoms [1.6.3, 1.6.6]:

Severe or frequent diarrhea (more than five watery stools per day)
Diarrhea lasting more than two days [1.6.3]
Severe abdominal pain or cramping
Fever [1.6.2]
Blood or pus in your stool [1.6.2, 1.6.4]
Signs of dehydration, such as intense thirst, dry mouth, little to no urination, weakness, or dizziness [1.6.1, 1.6.3]

Conclusion

Antibiotic-associated diarrhea is a frequent and usually manageable side effect. The primary response involves maintaining hydration and adopting a bland diet. Incorporating probiotics can also be an effective preventative and supportive measure [1.4.6]. However, it's vital to remain vigilant for signs of a more severe infection like C. diff. Never hesitate to contact a healthcare professional for guidance, especially if your symptoms are severe or persistent. Always follow your doctor's advice and do not stop your antibiotic treatment or take anti-diarrheal medication without their approval [1.9.5].

For more information on C. difficile, you can visit the CDC's page on the topic.

Frequently Asked Questions

No, you should not stop taking your antibiotic without first consulting your doctor. Stopping the medication early could prevent the full treatment of your original infection. Contact your provider to discuss your symptoms; they may switch you to a different antibiotic [1.6.3].

For mild cases, the diarrhea usually begins a few days after starting the antibiotic and ends a few days after you finish the treatment [1.6.3]. If it persists longer or is severe, you should contact your doctor.

You should check with your doctor before taking any anti-diarrheal medication. While it may be recommended for mild cases, it can be dangerous if your diarrhea is caused by a C. difficile infection because it can prevent your body from clearing the toxins [1.9.1, 1.9.4].

Studies have shown that probiotics containing Lactobacillus rhamnosus or Saccharomyces boulardii are particularly effective at preventing antibiotic-associated diarrhea. Doses of 5 to 40 billion colony-forming units (CFUs) per day are often suggested [1.4.2, 1.4.6].

It is best to avoid high-fiber foods, fatty or fried foods, spicy foods, and most dairy products (with the exception of probiotic yogurt). You should also avoid alcohol and caffeine, as they can worsen symptoms [1.5.2, 1.3.1].

Clostridioides difficile (C. diff) is a bacterium that can cause severe diarrhea and colitis. When antibiotics wipe out the good bacteria in the gut, C. diff can multiply and release toxins, leading to infection. It is the most common cause of more serious antibiotic-associated diarrhea [1.2.4, 1.7.2].

You should seek immediate medical attention if you have signs of severe dehydration (dizziness, no urination, intense thirst), a high fever, severe abdominal pain, or blood or pus in your stool [1.6.3, 1.6.5, 1.6.6].