Which adverse effect of lamotrigine is most concerning?

A. Photosensitivity: Photosensitivity can occur with some anticonvulsants, but it is not a hallmark or high-risk adverse effect of lamotrigine. When present, it is typically mild and manageable with sun protection. It does not usually indicate a serious systemic reaction. B. Headache: Headache is a relatively common and nonspecific side effect associated with many antiepileptic medications. It is often transient and does not suggest a severe or life-threatening complication. Symptomatic management is usually sufficient. C. Dizziness: Dizziness reflects central nervous system effects related to lamotrigine initiation or dose changes. While it may increase fall risk, it is generally dose-related and self-limiting. It does not signal a dangerous immune-mediated response. D. Fever: Fever may be an early indicator of a serious hypersensitivity reaction associated with lamotrigine, including Stevens–Johnson syndrome or toxic epidermal necrolysis. These reactions involve immune activation and can progress rapidly. Fever warrants immediate evaluation and possible discontinuation of the medication.