A 55-year-old woman on fluoxetine, carbamazepine and recently started cimetidine develops sore throat, mouth ulcers and fever. What is the most appropriate initial action?

• A. Take an over-the-counter throat lozenge and monitor symptoms
• B. Stop all medications temporarily and reassess in a week
• C. See the GP immediately
• D. Ask a pharmacist for a different reflux medicine

Answer: (C)

The key issue here is a potential serious drug interaction causing bone marrow suppression. Cimetidine can inhibit enzymes that metabolize carbamazepine, raising carbamazepine levels. Carbamazepine can cause neutropenia or agranulocytosis, and sore throat, mouth ulcers, and fever can be signs of an infection in the setting of low neutrophils. This combination creates a risk that requires urgent medical assessment rather than waiting or trying self-management.

Seeing a GP immediately is the right move because they need to check a full blood count and review the medication plan. They may need to stop or adjust carbamazepine, reassess the need for cimetidine (or switch reflux therapy), and manage any infection risk. This cannot be safely managed with an over-the-counter remedy, delaying care, or by stopping all medications without medical guidance. A pharmacist can discuss safer reflux options, but the symptoms here demand urgent medical evaluation to rule out or treat potential neutropenia.