Final answer:
A patient prescribed with metronidazole should avoid alcohol due to the risk of severe disulfiram-like reactions causing unpleasant symptoms.
Step-by-step explanation:
A patient that has been prescribed metronidazole should avoid alcohol. Metronidazole is an antibacterial and antiprotozoal medication that can cause a severe reaction when combined with alcohol. This reaction, sometimes known as a disulfiram-like reaction, can lead to symptoms such as nausea, vomiting, flushing, headache, and palpitations. Patients taking metronidazole should also be cautious with other substances; however, it is specifically with alcohol that the interaction is most severe and well-documented.