Does Leqembi (lecanemab) cause nightmares?

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Last updated: May 19, 2025View editorial policy

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From the Research

Leqembi (lecanemab) has not been widely reported to cause nightmares as a common side effect, and the most recent and highest quality study 1 confirms that sleep disturbances, including nightmares, are not listed among the primary side effects in clinical trials. The most frequently reported side effects of Leqembi include infusion-related reactions, headache, and ARIA (Amyloid-Related Imaging Abnormalities), which can involve brain swelling or small brain bleeds. Some key points to consider about Leqembi include:

  • The therapeutic regimens vary across reported studies and trials, ranging from 2.5 mg/kg biweekly, 5 mg/kg monthly, 5 mg/kg biweekly, 10 mg/kg monthly, and 10 mg/kg intravenously biweekly 1.
  • The Clarity AD phase 3 trial, the AHEAD study, and the DIAN-TU-001 trials have reported positive study outcomes with robust efficacy and safety outcomes with minimal side effects 1.
  • Completed and ongoing trials report on the onset of amyloid-related imaging abnormalities (ARIA) and the continuation of care status following the onset of ARIA in these patients 1. However, all medications can affect individuals differently, and some patients might experience unusual side effects not commonly reported. If you're taking Leqembi and experiencing nightmares, it's essential to discuss this with your healthcare provider, as they can help determine if the medication is the cause or if other factors might be contributing to your sleep disturbances, and suggest monitoring your symptoms, adjusting the timing of your medication, or considering other approaches to manage these effects while continuing treatment.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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