Moderate
Calcium carbonate × Ciprofloxacin
Mineral supplements. Calcium×Fluoroquinolone antibacterials
Mechanism
Calcium forms insoluble chelates with ciprofloxacin in the gut. Antibiotic bioavailability falls by 40–50%, raising the risk of clinical failure.
Symptoms
Persistent fever, infection symptoms, and inflammation markers 48–72 hours after antibiotic start.
Management
Take ciprofloxacin 2 hours before or 6 hours after calcium carbonate. Apply the same interval for iron, zinc, magnesium, and aluminium-containing antacids. If timing separation is impossible (e.g. continuous calcium need), choose an alternative antibiotic (amoxicillin-clavulanate, a cephalosporin).
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.