Amoxicillin is a frequently prescribed antibiotic for babies, used to treat various bacterial infections. While effective, a known and common side effect is diarrhea. Parents should be aware this can occur during or after the course of treatment. Understanding why this happens and how to manage it can help ease concerns and ensure the baby’s well-being.
Why Diarrhea Can Occur
Antibiotics, including amoxicillin, eliminate harmful bacteria causing infections. However, they are not selective and also affect beneficial gut bacteria, known as the gut microbiota. This disrupts the natural balance of microorganisms in the intestines.
When the balance of beneficial bacteria is disturbed, other bacteria, including potentially harmful ones, can multiply excessively. This overgrowth interferes with normal digestive processes and nutrient absorption. As a result, stool consistency changes, leading to loose or watery bowel movements. This phenomenon, known as antibiotic-associated diarrhea, is a common side effect across many types of antibiotics, not just amoxicillin.
Managing Diarrhea
When a baby experiences diarrhea while taking amoxicillin, maintaining hydration is a primary concern. Continue feeding with breast milk or formula is important, as these provide essential fluids and nutrients. For older babies on solids, oral rehydration solutions (ORS) can replace lost fluids and electrolytes. Avoid fruit juices or carbonated beverages, as these can worsen diarrhea.
Most cases of antibiotic-associated diarrhea are mild and tend to resolve within a few days to two weeks after the antibiotic course is completed. Unless advised by a healthcare provider, it is important to continue the full course of amoxicillin as prescribed, even if diarrhea occurs. Probiotics, which introduce beneficial bacteria, might help restore gut balance, but their use should always be discussed with a pediatrician first. Keeping the diaper area clean and dry, and applying a barrier cream, can prevent or soothe diaper rash caused by frequent, acidic stools.
When to Seek Medical Advice
While antibiotic-associated diarrhea is often mild, certain signs indicate the need for prompt medical attention. Dehydration is a concern, especially in infants. Symptoms include decreased urination (fewer wet diapers), dry mouth or tongue, absence of tears when crying, sunken eyes, or a sunken soft spot on the head. Lethargy or unusual drowsiness also warrant immediate evaluation.
Other red flags include severe abdominal pain or cramping, high fever, or the presence of blood or mucus in the stool. Diarrhea that is very frequent (e.g., 10 or more watery stools in 24 hours) or persistent for over two weeks should also be evaluated by a doctor. In rare cases, antibiotic use can lead to a more severe infection caused by Clostridioides difficile (C. difficile), which can manifest with severe diarrhea, abdominal pain, and fever. If any concerning symptoms appear, contacting a healthcare provider is essential.