A 6‑year‑old boy (35 kg) with impetigo receiving oral co‑amoxiclav suspension 642 mg (10 mL) every 8 hours for 7 days plus topical mupirocin develops diarrhea on day 2; should the antibiotic dose be reduced or discontinued?

Management of Diarrhea in a Child on Co‑Amoxiclav for Impetigo

Do not reduce or discontinue the co‑amoxiclav; instead, reassure the family that mild diarrhea is a common, expected side effect that typically resolves without intervention, and continue the full 7‑day course to ensure complete eradication of the impetigo.

Understanding Antibiotic‑Associated Diarrhea in This Context

• Diarrhea is a common problem caused by antibiotics and usually ends when the antibiotic is discontinued; many antibiotics can cause diarrhea, and if it is severe or lasts more than 2 or 3 days, the physician should be contacted. 1
• Co‑amoxiclav (amoxicillin‑clavulanate) is associated with gastrointestinal upset, and each dose should be taken with a meal or snack to reduce the possibility of this side effect. 1
• The clavulanate component is the primary driver of diarrhea, causing osmotic effects in the gut; this is dose‑related and typically mild to moderate in severity. (General medical knowledge, supported by FDA labeling 1)

Decision Algorithm: Continue vs. Modify Therapy

Continue Current Therapy (Most Appropriate)

• The standard treatment duration for oral antibiotics in impetigo is 7 days, and skipping doses or not completing the full course may decrease the effectiveness of treatment and increase the likelihood that bacteria will develop resistance. 1
• For impetigo with numerous lesions or when topical therapy is impractical, oral co‑amoxiclav is an acceptable alternative and should be completed as prescribed. 2
• Mild diarrhea on day 2 does not constitute treatment failure or a serious adverse event requiring discontinuation; the infection requires the full 7‑day course for adequate bacterial eradication. 2, 3

When to Modify or Stop Therapy

• Discontinue the antibiotic and contact the physician if the patient develops watery and bloody stools (with or without stomach cramps and fever), even as late as 2 or more months after the last dose, as this may indicate Clostridioides difficile infection. 1
• If diarrhea is severe (≥6 watery stools per day), persists beyond 2–3 days, or is accompanied by fever, abdominal pain, or blood in stool, the physician should be contacted immediately. 1
• If superinfections occur (usually involving Pseudomonas or Candida), the drug should be discontinued and/or appropriate therapy instituted. 1

Practical Management Steps

Symptomatic Relief Without Stopping Antibiotics

• Ensure each dose of co‑amoxiclav is taken with a meal or snack to minimize gastrointestinal upset. 1
• Maintain adequate hydration with oral fluids; mild diarrhea in a 6‑year‑old can be managed with increased water, diluted juice, or oral rehydration solutions. (General pediatric practice)
• Probiotics (e.g., Lactobacillus or Saccharomyces boulardii) may be considered to reduce antibiotic‑associated diarrhea, though evidence is mixed and they should not replace completion of the antibiotic course. (General medical knowledge)

Monitoring for Red Flags

• Watch for signs of dehydration (decreased urine output, dry mucous membranes, lethargy) and escalate care if present. (General pediatric practice)
• Monitor for progression to severe diarrhea (≥6 stools/day), bloody stools, high fever (>39°C), or severe abdominal pain, all of which warrant immediate physician contact. 1

Why Dose Reduction Is Not Appropriate

• Reducing the dose of co‑amoxiclav would compromise antimicrobial efficacy and increase the risk of treatment failure and bacterial resistance. 1
• The 642 mg dose (10 mL) every 8 hours is the standard pediatric regimen for a 35 kg child with impetigo, and subtherapeutic dosing would not adequately cover Staphylococcus aureus and Streptococcus pyogenes. 2, 3
• Mild diarrhea is not an indication to reduce antibiotic dosing; only severe or complicated adverse events (e.g., C. difficile colitis, anaphylaxis) warrant discontinuation. 1

Alternative Antibiotic Considerations (If Diarrhea Becomes Intolerable)

• If diarrhea becomes severe enough to warrant switching antibiotics, oral cephalexin 25–50 mg/kg/day divided into 4 doses for 7 days is a first‑line alternative for presumed methicillin‑susceptible S. aureus impetigo. 2
• Clindamycin syrup 20–30 mg/kg/day divided into 3 doses for 7 days is another option when MRSA is suspected or if the patient cannot tolerate beta‑lactams. 2
• Topical mupirocin 2% ointment applied twice daily for 5 days is highly effective for limited impetigo and may be superior to oral antibiotics, avoiding systemic side effects entirely. 2, 4, 5

Key Pitfalls to Avoid

• Do not stop antibiotics prematurely based on mild diarrhea alone; this increases the risk of treatment failure and bacterial resistance. 1
• Do not assume all diarrhea is benign; severe or bloody diarrhea, especially with fever or abdominal pain, may indicate C. difficile infection and requires immediate evaluation. 1
• Do not reduce the dose of co‑amoxiclav in an attempt to minimize diarrhea; subtherapeutic dosing will not adequately treat the impetigo. 1
• Do not overlook the importance of taking each dose with food, as this simple measure significantly reduces gastrointestinal side effects. 1