A nurse is teaching a client who is beginning a course of metronidazole to treat a bacterial infection. For which of the following findings of an adverse effect should the nurse instruct the client as a priority to Stop taking metronidazole and notify the provider?

A. Incorrect: A metallic taste is a common but mild side effect and does not require stopping the medication. B. Incorrect: Dark-colored urine is a harmless and expected side effect of metronidazole. C. Incorrect: Nausea is a common side effect but not a reason to discontinue the medication. D. Correct: Seizures are a serious adverse effect of metronidazole and require immediate discontinuation and medical evaluation.