Minor
Calcium carbonate × Metronidazole
Mineral supplements. Calcium×Imidazole derivatives (antiprotozoal / antibacterial)
Mechanism
Calcium carbonate as an antacid may theoretically reduce metronidazole absorption, but no clinically significant effect on antibacterial efficacy has been described.
Symptoms
The combination usually causes no specific symptoms. Each drug's individual side effects remain.
Management
For short metronidazole courses (5–10 days), no specific adjustment needed. In Helicobacter pylori eradication (with bismuth or a PPI), the combination is standard.