Key takeaways

  • Leqembi (lecanemab-irmb) is a prescription drug that’s used to treat Alzheimer’s disease.
  • The drug comes as a liquid that’s given as an infusion into a vein. It is usually given once every 2 weeks.
  • Dosage of Leqembi is based on body weight in kilograms (kg).

Leqembi is prescribed to treat Alzheimer’s disease in adults with:

  • mild cognitive impairment
  • mild dementia (problems with thinking, memory, and communication)

Learn about the dosages of Leqembi as well as its forms, strengths, and how it is given.

Leqembi is available as a liquid solution in a vial. It comes in a strength of 100 milligram per milliliter (mg/mL). Your doctor may order it in a 2-mL or 5-mL vial.

Leqembi is also available as single-dose prefilled autoinjector under the name Leqembi IQLIK. It comes in one strength of 200 mg/mL.

The information below describes the dosage that’s commonly prescribed or recommended. But your doctor will determine the best dosage to fit your needs.

The usual Leqembi dosage for adults with Alzheimer’s disease depends on body weight in kilograms (kg). For reference, 1 kg is about 2.2 pounds (lb).

The recommended starting dose is 10 mg/kg. Your doctor will calculate and prescribe the correct dose for you. You’ll receive this dose as an IV infusion once every 2 weeks.

After 18 months, you may continue to receive 10 mg/kg every 2 weeks as an IV infusion. Or, your doctor may decide to change your dosage to 10 mg/kg every 4 weeks as an IV infusion. Your doctor may also decide to switch you to the subcutaneous injection form of the drug, Leqembi IQLIK, with a dosage of 360 mg given once weekly.

Talk with your doctor if you have questions about the dosage of Leqembi, including what may determine whether a dosage is changed after 18 months.

Is Leqembi prescribed long term?

Yes, Leqembi is usually prescribed as a long-term treatment. If you and your doctor determine that it’s safe and effective for your condition, you’ll likely receive it long term.

Dosage adjustments

Your doctor may adjust your dosing frequency of Leqembi based on side effects you experience, including the presence of amyloid-related imaging abnormalities (ARIA) on a brain scan.

Depending on the severity of the side effects, your doctor may choose to temporarily stop treatment with Leqembi until the side effect resolves. Afterward, your doctor may decide to resume your treatment with Leqembi, or they may recommend a different treatment they think would be safer.

You’ll receive Leqembi at your doctor’s office or at a clinic.

Leqembi comes as a liquid solution in a vial. The small volume of liquid in the vial is first diluted in a larger volume of liquid saline solution by a healthcare professional. You’ll then receive the medication as an intravenous (IV) infusion for about 1 hour. (An IV infusion is an injection into your vein given over time.)

Some people may experience an infusion-related reaction at the time of the infusion. Symptoms may include fever, chills, and nausea. A reaction can also cause changes in blood oxygen level and blood pressure. If this occurs, your doctor will stop the infusion and provide treatment for the reaction. The infusion can usually be started again but at a slower rate.

If you’ve had this experience, your doctor will likely give you medication to help prevent this reaction before your next infusion. Medications they may recommend to help prevent an infusion-related reaction include:

Leqembi IQLIK

Leqembi IQLIK is given as a subcutaneous injection (injection under the skin).

Before injecting Leqembi IQLIK, remove it from the refrigerator and let it sit at room temperature for 20 minutes. Do not shake the pen.

You can inject Leqembi IQLIK into your abdomen, upper thigh, or the back of your upper arm. Be sure to avoid moles, scars, bruises, tattoos or areas where the skin is red, hard, or tender.

Below are answers to some commonly asked questions about Leqembi’s dosage.

Leqembi and Aricept (donepezil) are both prescribed to treat Alzheimer’s disease. But their forms, dosing schedules, and the way the drugs work in the body are different.

Leqembi comes as a liquid solution that’s given as an intravenous (IV) infusion or subcutaneous injection. The dose based on body weight and it is given either every 1, 2, or 4 weeks. Aricept is available as a pill that’s swallowed. It is usually taken once per day.

Your doctor will prescribe the drug and the dosage that’s right for you. To learn more about how these drugs compare, talk with your doctor.

Leqembi starts to work after your first dose. Because of how the drug works, you likely won’t feel the drug working in your body.

The exact cause of Alzheimer’s disease isn’t known, but a buildup of a substance called beta-amyloid is thought to play an important role. Leqembi works to reduce the amount of beta-amyloid plaques in the brain. In studies, fewer beta-amyloid plaques were seen on PET scan imaging after 13 weeks of Leqembi treatment.

Your doctor will monitor how your condition responds to treatment with Leqembi. If you have questions about what to expect from your treatment, talk with your doctor.

If you miss an IV infusion of Leqembi, get your next dose as soon as possible. If you miss a Leqembi IQLIK weekly injection, take it as soon as you can within 6 days, then take the next dose on your usual scheduled day.

Disclaimer: While Healthline strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.