Lecanemab is used to treat adults with Alzheimer's disease.

Lecanemab may also be used for purposes not listed in this medication guide.

Lecanemab can cause a condition called Amyloid Related Imaging Abnormalities or "ARIA" which is a temporary swelling or small spots of bleeding in the brain that usually clears up with time. Your doctor may perform an MRI of your brain before and during your treatment with lecanemab. Ask your doctor about your risk.

It is not known if lecanemab will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Ask a doctor if it is safe to breastfeed while using this medicine.

Use Lecanemab (Injection) (Intravenous) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection. Tell your medical caregiver if you feel dizzy, nauseated, light-headed, itchy, sweaty, or have a headache, flu-like symptoms, fever, or vomiting; chest tightness, fast/slow heartbeats or pounding heartbeats, back pain, trouble breathing, or swelling in your face.

Common side effects may include:

• ARIA with symptoms or with signs that appear on an MRI;
• infusion-related reactions; or
• headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.