Note: This document contains side effect information about lecanemab. Some dosage forms listed on this page may not apply to the brand name Leqembi.

Applies to lecanemab: intravenous solution.

Serious side effects of Leqembi

Along with its needed effects, lecanemab (the active ingredient contained in Leqembi) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking lecanemab:

More common

• Back pain
• blurred or changes in vision
• chest tightness
• chills
• confusion
• diarrhea
• dizziness
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• drowsiness
• feeling shaky
• fever
• flushing
• general feeling of discomfort or illness
• headache
• joint pain
• loss of appetite
• muscle aches and pain
• nausea and vomiting
• nervousness
• pale skin
• pounding in the ears
• runny nose
• seizures
• shivering
• slow or fast heartbeat
• sore throat
• sweating
• trouble breathing
• trouble sleeping
• unusual tiredness or weakness

Less common

• Cough or hoarseness
• lower back or side pain
• painful or difficult urination

For Healthcare Professionals

Applies to lecanemab: intravenous solution.

General

The most common adverse reactions reported were infusion-related reactions, headache, and amyloid related imaging abnormalities.^[Ref]

Cardiovascular

Common (1% to 10%): Atrial fibrillation^[Ref]

Gastrointestinal

Common (1% to 10%): Diarrhea^[Ref]

Hematologic

Common (1% to 10%): Lymphopenia^[Ref]

Other

Very common (10% or more): Infusion-related reactions (20%)^[Ref]

Respiratory

Common (1% to 10%): Cough^[Ref]

Nervous system

Very common (10% or more): Amyloid related imaging abnormalities (10%), headache (14%)^[Ref]