A nurse is caring for a client who is taking disulfiram for alcohol use disorder and reports ingestion of alcohol. For which of the following adverse effects should the nurse monitor?

The correct answer is B: Headache. Disulfiram causes an unpleasant reaction when alcohol is consumed, leading to symptoms like headache, nausea, vomiting, and flushing. Headache is a common side effect due to the inhibition of aldehyde dehydrogenase, causing acetaldehyde buildup. Hypertension is not a typical reaction to disulfiram-alcohol interaction. Insomnia is not a direct effect but may occur due to discomfort. Tinnitus is also not a common symptom associated with disulfiram use. Monitoring for headache is crucial to assess the effectiveness of disulfiram therapy and encourage abstinence from alcohol.