A nurse is assessing a client who has systemic lupus erythematosus and is taking hydroxychloroquine. The nurse should report which of the following adverse effects to the provider immediately?

Choice A rationale Diarrhea is a common gastrointestinal side effect of hydroxychloroquine, generally managed symptomatically, but is not typically an immediate life-threatening concern. The drug's mechanism involves immunomodulation; gastrointestinal upset is often a direct irritation effect. Choice B rationale Pruritus (itching) is a frequent dermatological adverse effect, likely a hypersensitivity reaction, but it does not represent an acute, potentially irreversible organ damage requiring immediate cessation or intervention. Choice C rationale Blurred vision can be a sign of irreversible retinal toxicity (retinopathy), a rare but serious adverse effect associated with hydroxychloroquine, which can lead to permanent vision loss. Immediate reporting is necessary for prompt ophthalmologic evaluation and drug discontinuation. Choice D rationale Fatigue is a non-specific and common symptom in clients with systemic lupus erythematosus itself, and can be a side effect of many medications. While it should be monitored, it does not suggest acute, irreversible organ damage like retinal toxicity.