Haemophagocytic lymphohistiocytosis precipitated by lamotrigine.

Haemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening hyperinflammatory syndrome of uncontrolled systemic inflammation. In 2018, the US Food and Drug Administration issued a safety warning of the risk of HLH after starting lamotrigine. Early recognition and prompt and effective immunosuppression, alongside trigger identification, are essential for a good outcome in HLH. We report two cases of HLH temporally associated with lamotrigine initiation. Both patients had presented with refractory fever, falling cell counts and hyperferritinaemia-the hallmark 3Fs of HLH-and were admitted to critical care with multiorgan failure within 10 days of starting lamotrigine. They received treatment for HLH with intravenous corticosteroids, immunoglobulin and anakinra; lamotrigine was withdrawn. Both patients recovered fully following protracted hospital admissions and remain stable on alternative antiseizure medication. HLH is a very rare but life-threatening complication of lamotrigine therapy. Appropriate consent and clinical vigilance are relevant to clinicians using lamotrigine in clinical practice.