Can Antibiotics Cause Diarrhea or Chronic Diarrhea?

Key takeaways:

• Diarrhea is a common side effect of many antibiotics
• Antibiotic-induced diarrhea can sometimes indicate a more serious infection, such as Clostridium difficile, known as C. diff.
• Other things can cause diarrhea besides antibiotics, so knowing what to look for can help you determine the cause.
• Learning to recognize when your symptoms require medical attention is important so you can avoid complications such as dehydration.

Antibiotics are routinely used to treat all kinds of bacterial infections, ranging from skin infections to pneumonia. While antibiotics are very effective, like all medications they can have side effects. One of the relatively common side effects is diarrhea, particularly with certain antibiotics, which can affect children as well as adults and older people.

Diarrhea often happens because the antibiotics disrupt the balance of normal bacteria in your gut. In some cases, this can progress to a more serious infection which requires medical attention. Let’s explore how antibiotics cause diarrhea, how to tell when diarrhea is from an antibiotic or may be due to something else, and what to do about it.

Is it normal to experience diarrhea when taking antibiotics?

Diarrhea is a well recognized side effect of taking an antibiotic. This is especially true for those antibiotics that are considered broad-spectrum, meaning they target a wide range of bacteria.

While in some cases this broad spectrum of activity can be an advantage, these antibiotics don’t discriminate between harmful and beneficial bacteria. This means they have the potential to upset the balance in your gut’s good bacteria which can often lead to diarrhea.

Studies show that up to 30% of people taking antibiotics can experience diarrhea. Symptoms can appear shortly after you begin taking the medication and may last even after you finish your prescription.

In many cases, the diarrhea is mild and stops once you have finished the antibiotic. If you have diarrhea that continues or is severe, this could be a sign of an infection or a reaction to the medication and should be discussed with your physician.

Antibiotics most commonly linked to diarrhea

Certain antibiotics are much more likely to cause diarrhea than others. Broad-spectrum antibiotics, such as amoxicillin-clavulanate (brand name Augmentin), cephalosporins (brand names Keflex and Duricef), and clindamycin (brand name Cleocin), are often associated with this side effect. This is because they have an impact on a wider range of gut bacteria, both good and bad.

Tetracyclines, fluoroquinolones (like ciprofloxacin), and macrolides (such as erythromycin) can also cause digestive upset in some people. If you are particularly sensitive to antibiotics or have experienced digestive issues in the past, you should discuss alternatives with your healthcare provider.

How antibiotics can cause diarrhea

Antibiotics can cause diarrhea by changing the normal balance of bacteria in your gut. This imbalance can often lead to an overgrowth of less beneficial bacteria, which can affect your digestion and the consistency of your stool.

When your gut is healthy, all of the various bacterial species in your intestinal tract coexist as a balanced community known as your microbiome. When you take an antibiotic, your microbiome may become unbalanced due to the reduction of the population of protective bacteria. This imbalance can lead to a condition known as antibiotic-associated diarrhea (AAD), in which you have loose, watery stools as well as an increased frequency of bowel movements.

Sometimes, the diarrhea that results from antibiotics may be caused by a bacterial infection, most commonly Clostridium difficile known as C. diff. This bacteria thrives in unbalanced microbiomes and can cause severe diarrhea, abdominal pain, and fever. An infection with C. diff requires prompt medical treatment.

The role of gut flora

The term “gut flora” is simply another name for your microbiome, the community of bacteria living in your intestines.

Your gut flora is vital to the maintenance of your digestive health, as these bacteria help to break down food, make certain vitamins, and protect the lining of your gut. If antibiotics disrupt your gut flora, this can lead to diarrhea, bloating, and even symptoms that may resemble irritable bowel syndrome (IBS).

How to tell the difference between diarrhea from antibiotics and other causes of diarrhea

Figuring out if diarrhea is being caused by antibiotics or is from another cause can be tricky, as symptoms may overlap.

Typically, antibiotic-related diarrhea develops shortly after you have started taking a new medication, often within a few days of your first dose. If your symptoms began immediately after starting antibiotics, it’s more likely that the diarrhea is related to the medication. If the diarrhea goes away shortly after you have finished taking your medication, then this is another clue that the antibiotic caused your symptoms.

If you have diarrhea that goes beyond the course of your antibiotics, or you have other symptoms such as blood in your stool, fever, or abdominal pain, you may have another underlying condition. Spoiled or contaminated food, IBS, viral infections, and food intolerances can all lead to diarrhea.

Monitoring symptoms

Carefully keeping track of your symptoms can help you to identify the cause of diarrhea. You should note the frequency, color, and consistency of your stool as these can all provide clues.

For example, if your diarrhea is accompanied by intense cramping, nausea, or vomiting, then a foodborne illness or a viral infection might be the cause. Keeping a symptom diary can help you track patterns and is also very useful if you need to discuss your symptoms with your physician.

Other common causes of diarrhea

Other things besides antibiotics can also cause diarrhea. Here are some common causes that are not related to antibiotics:

Food poisoning

Eating food contaminated with bacteria or viruses can result in symptoms like diarrhea, abdominal pain, and vomiting. This can happen if food is improperly cooked, stored, or handled.

Gastroenteritis

Gastroenteritis is often called the “stomach flu.” It is caused by a viral or bacterial infection and symptoms include diarrhea, vomiting, and fever.

Lactose intolerance

If you have lactose intolerance, you may experience diarrhea and cramping after you eat dairy products. This condition is due to a deficiency in lactase, the enzyme needed to digest lactose, a sugar found in milk and other dairy products.

Stress and anxiety

For some people, emotional distress can lead to gastrointestinal symptoms, including diarrhea, as the gut and the brain are closely connected.

Read our guides on types of diarrhea and common causes of diarrhea for more.

When to see a doctor about diarrhea while on antibiotics

Although mild diarrhea is usually not a cause for alarm, there are certain situations in which medical advice is necessary.

You should see a doctor if:

• Your diarrhea continues for more than two days without improvement.
• You experience other symptoms, such as fever, dehydration, or weight loss.
• There is blood, mucus, or a foul odor with your stool, which may mean a serious infection.

You should go to the emergency room if:

• Your diarrhea is severe and results in symptoms of dehydration like extreme thirst, dark-colored urine, a fast heart rate, and dizziness.
• You have a high fever (above 101°F) or abdominal pain that doesn’t improve with over-the-counter medications.

Questions to ask your doctor about diarrhea while on antibiotics

Consider asking your healthcare provider the following questions:

• Are my symptoms likely caused by the antibiotic, or could there be another cause?
• Would a probiotic or dietary supplement help reduce my symptoms?
• Are there alternative antibiotics or treatments that you could suggest that may be easier on my digestive system?
• If my symptoms get worse, what should I do, and when should I seek emergency care?

How to treat or get relief from diarrhea while on antibiotics

These strategies may help to reduce the impact of diarrhea while on antibiotics, but it’s important to consult a healthcare provider for guidance if you have severe diarrhea or other symptoms.

Probiotics

Probiotics are live microorganisms that can help restore a healthy balance of bacteria in your gut.

Consuming yogurt, kefir, or taking probiotic supplements may aid in reducing antibiotic-related diarrhea. Restoring gut flora with probiotics or prebiotic-rich foods may help to decrease symptoms in some people.

Stay hydrated

Diarrhea can cause dehydration, so drinking plenty of fluids, including water and oral rehydration solutions such as some sports drinks or PediaLyte™ can help to replace lost fluids and electrolytes.

Adjust your diet:

Eating bland foods like bananas, rice, applesauce, and toast (the BRAT diet) can help to ease your diarrhea symptoms. You should avoid high-fiber or fatty foods, as these can make your diarrhea worse.

Frequently asked questions: diarrhea and antibiotics

Can antibiotics cause black-colored diarrhea?

No, antibiotics don’t usually cause black stools. Black-colored diarrhea may mean you have bleeding in your gastrointestinal system.

This needs to be promptly evaluated by your physician. Certain medications, like iron supplements or Pepto-Bismol™ can also cause darkened, black colored stools.

Can antibiotic eye drops cause diarrhea?

Since antibiotic eye drops are applied locally in your eyes, they have minimal absorption into your bloodstream and are unlikely to cause diarrhea. Digestive side effects are more common with antibiotics taken by mouth or through an IV.

Do intravenous antibiotics cause diarrhea?

Yes, intravenous (IV) antibiotics can disrupt your gut bacteria and cause diarrhea, especially if you are on them for an extended time. This route allows antibiotics to circulate in your bloodstream, and from there they can impact your gut microbiome.

Are older adults more likely to have diarrhea while on antibiotics?

Yes, older adults may be at higher risk for antibiotic-related diarrhea, as their gut microbiome can be more sensitive to disruption than a younger person. They also may be susceptible to serious infections like C. difficile as immunity generally decreases as a person ages.

In review

Antibiotic-related diarrhea is a common experience for many people, with symptoms usually going away after the course of medication is completed. While most cases are mild, severe or prolonged diarrhea can mean you have a more serious condition that requires medical attention. By being aware of the risks and knowing when you should get medical advice, you can manage your symptoms more effectively and recover more quickly.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Jennifer Nadel, MD.

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Kesavelu, Dhanasekhar, and Pramod Jog. “Current Understanding of Antibiotic-Associated Dysbiosis and Approaches for Its Management.” Therapeutic Advances in Infectious Disease, vol. 10, 2023, article 20499361231154443. PubMed Central,https://pmc.ncbi.nlm.nih.gov/articles/PMC9969474/.

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