A nurse is teaching a client who is prescribed metronidazole for a gastrointestinal infection. Which instruction should the nurse include to promote safe and effective use of the medication?

A. Taking metronidazole with antacids is not necessary for gastrointestinal upset and may alter the absorption of the medication. Clients should take it as prescribed, usually with food if gastrointestinal discomfort occurs, but antacids are not required. B. Metronidazole can cause a disulfiram-like reaction when combined with alcohol, leading to symptoms such as flushing, nausea, vomiting, headache, and palpitations. Clients should avoid alcohol during therapy and for at least 48 hours after the last dose to prevent this reaction. This instruction is crucial for safe use. C. Metronidazole is an antibacterial and antiprotozoal agent, not effective against viral or fungal infections. Expecting it to treat viral or fungal infections indicates a misunderstanding of its therapeutic use. D. A metallic taste in the mouth is a common and harmless side effect of metronidazole. Clients should be informed that this taste may occur but does not require discontinuation of the medication. Stopping the drug unnecessarily can compromise treatment effectiveness.