Which of the following medications can cause loose stools: paracetamol, Tamiflu (oseltamivir), amoxicillin-clavulanate, Zyrcold (cetirizine and ambroxol), or vitamin D?

Which Medications Can Cause Loose Stools

Amoxicillin-clavulanate (Amoxclav) and Tamiflu (oseltamivir) are the primary culprits for causing loose stools among the medications listed, with amoxicillin-clavulanate being the most frequent offender.

Amoxicillin-Clavulanate (Amoxclav) - Highest Risk

Diarrhea/loose stools is the most frequently reported adverse reaction with amoxicillin-clavulanate, occurring in 9% of patients. 1

• The FDA drug label explicitly states that diarrhea/loose stools occurs in 9% of patients, making it the single most common side effect 1
• The incidence increases with higher doses 1
• Co-amoxiclav specifically carries a 2.08 times higher risk of antibiotic-associated diarrhea compared to other antibiotics 2
• This medication is among the "worst offenders" for causing antibiotic-associated diarrhea and pseudomembranous colitis 3
• Patients should be counseled that diarrhea is a common problem with this antibiotic, and to contact their physician if diarrhea is severe or lasts more than 2-3 days 1

Mechanism and Timing

• Diarrhea typically appears during the first few days of treatment 4
• Can occur through multiple mechanisms: altered gut flora, osmotic effects, and potential C. difficile overgrowth 1
• Taking each dose with a meal or snack may reduce gastrointestinal upset 1

Tamiflu (Oseltamivir) - Moderate Risk

While not explicitly detailed in the provided evidence, oseltamivir is known to cause gastrointestinal side effects including loose stools, though less frequently than amoxicillin-clavulanate 4

Medications with Minimal to No Risk

Paracetamol (Medomol)

• Not associated with causing loose stools or diarrhea 4, 5
• This is a safe option regarding gastrointestinal effects

Cetirizine and Ambroxol (Zyrcold)

• Neither cetirizine nor ambroxol are recognized causes of diarrhea 4, 5
• These medications do not appear in lists of drugs commonly causing loose stools

Vitamin D

• Not a recognized cause of diarrhea at therapeutic doses 4
• Generally well-tolerated gastrointestinally

Clinical Management Approach

If loose stools develop while on amoxicillin-clavulanate:

1. Assess severity immediately - Look for fever >38.5°C, blood in stool, severe abdominal pain, or signs of dehydration 6

2. For mild cases (uncomplicated diarrhea):

   • Continue the antibiotic if clinically necessary 6
   • Implement dietary modifications: eliminate lactose-containing products 6
   • Ensure adequate oral hydration 6
   • Consider loperamide 4 mg initially, then 2 mg after each loose stool (maximum 16 mg/day) 7

3. For severe or persistent cases:

   • Discontinue the antibiotic if possible 1
   • Evaluate for C. difficile infection if diarrhea persists beyond 2-3 days or worsens 1
   • Consider hospitalization if fever, bloody stools, or severe dehydration present 6

Critical Pitfall to Avoid

Do not use antiperistaltic agents (loperamide) if there is fever, bloody diarrhea, or suspected C. difficile infection, as this may worsen outcomes and mask serious complications 6