Back in January 2023, an Alzheimer’s drug called Leqembi® (generic name lecanemab-irmb) made history when the U.S. Food and Drug Administration (FDA) elected to accelerate its approval. Months later, Leqembi made history again. That’s when the FDA granted traditional approval for it—the first time it’s ever done so for a drug of its type.

Next to Aduhelm™, which was discontinued in 2024, Leqembi was only the second anti-amyloid Alzheimer’s disease treatment on the market.¹ It was also the first to qualify for broader coverage under original Medicare.²

“This was an important milestone and encouraging news for millions of people with early-stage Alzheimer’s who may benefit from Leqembi, but might otherwise face barriers to accessing or affording treatment,” said Dorothea Vafiadis, NCOA Senior Strategist for Healthy Aging. “Traditional FDA approval helps reduce some access barriers, but patients and caregivers should still talk with their doctor and weigh the treatment’s potential pros and cons.”

Get answers to commonly asked questions about this Alzheimer's treatment below.

What does the drug Leqembi do?

Leqembi is a biologic drug designed to slow Alzheimer’s progression by identifying and attacking beta amyloid proteins in the brain—what experts consider to be hallmarks of the disease. Beta amyloid proteins clump together to form plaques that destroy neurons, which are the cells that form the brain’s communication system.³ Leqembi binds to these plaques and breaks them apart.⁴

“There are other medications for Alzheimer’s on the market, but those only treat symptoms,” Vafiadis explained. “Leqembi addresses the underlying disease mechanism, with promising results in early clinical trials.”

What are the side effects of Leqembi?

Leqembi's long-term safety remains to be seen, Vafiadis cautioned. The drug’s potential side effects are serious enough that the FDA requires a boxed warning on its packaging.⁵

Leqembi’s most common side effects include:

• Headache
• Infusion-related reactions
• Temporary brain swelling
• Small brain bleeds

Together, those last two bullet points describe a phenomenon called amyloid-related imaging abnormalities, or ARIA. Most often, ARIA causes no symptoms and usually resolves over time. Some patients with ARIA will experience nausea, dizziness, confusion, or vision changes. Rarely, ARIA can cause life-threatening brain swelling and fatal brain hemorrhage. 

Certain patients are at higher risk for ARIA, including:⁵

• Those with the APOE4 gene mutation (a mutation correlated with Alzheimer’s)
• Those who use blood thinners
• Those with previous histories of microscopic brain bleeds

Patients should work closely with their health care team to fully understand their individual risks and weigh them against the potential benefits of Leqembi before deciding to try it.

Does Leqembi really work?

It depends. It’s important to know that Leqembi does not cure Alzheimer’s or reverse the changes that have already occurred due to the disease. But it can slow cognitive decline in patients with early-stage disease.

Results from Leqembi’s confirmatory study, which enrolled 1,795 patients with Alzheimer’s in a multi-center clinical trial, showed a “statistically significant” and “clinically meaningful” reduction in that decline over a period of 18 months for participants who received Leqembi versus those who received a placebo.⁵

That said, the way researchers measured and quantified their results necessarily were subjective, Vafiadis explained. That’s because they relied on participants to rate their own perceived changes during the course of the study. Using a five-point scale, participants described their performance in areas such as memory, problem-solving, and personal care at the beginning and end of the study. Researchers calculated the differences and concluded that those who received Leqembi experienced a 27% slower rate of cognitive decline than those who hadn't.⁵

This is currently the best way for clinical investigators to evaluate Leqembi’s outcomes, Vafiadis said, and those outcomes are encouraging. Newer research paints a favorable picture of the drug’s long-term efficacy as well. A study published in 2026 found that 94% of Alzheimer’s patients who completed 18 months of treatment with Lequembi chose to move on to maintenance treatment. They then continued to experience benefits from Lequembi compared to allowing the disease to run its course naturally.⁶

Leqembi may help some patients maintain their independence and ability to participate in daily life for longer. For many people with early-stage Alzheimer’s, that’s enough. 

Who can get Leqembi?

In theory, anyone diagnosed with early-stage Alzheimer’s disease who qualifies under FDA rules can get Leqembi. Currently, the drug is not approved for treating more advanced stages of the disease or for patients who do not show any symptoms.

Leqembi’s prescribing information requires that patients undergo diagnostic testing to confirm the presence of beta amyloids before they can begin treatment.⁷ Generally, doctors accomplish this with a PET scan or by examining cerebrospinal fluid obtained through a lumbar puncture (spinal tap).

Some people—those with lower incomes, for example, or limited English-language skills—do not have the same access to diagnostic testing as others, Vafiadis says. Because Leqembi is only approved for use in early-stage Alzheimer’s disease, many patients who might otherwise benefit from the drug will miss out under current guidelines. They simply will be diagnosed too late.

“That said, it’s worth noting that since Leqembi is a newer medication, we don’t yet have a full understanding of how safe and effective it is,” Vafiadis said, referring to another point made in the article: that other concurrent, underlying health issues may contribute to cognitive decline in certain populations who weren’t originally included in clinical trials.

“It’s possible that Leqembi would not be a good treatment choice in those situations,” she said. “That’s precisely why we need more robust studies that take these factors into account.”

How is Leqembi given and for how long?

Leqembi is not available in a pill form and is not taken by mouth. This medication is given intravenously (through a vein) by infusion over a one-hour period every two weeks for an indefinite period of time. At least for the initial treatment period (generally 18 months), patients prescribed Leqembi must go to an infusion clinic or other medical setting to receive the medication by infusion. This requirement raises further concerns for people who do not live near infusion centers or medical settings equipped to administer the medication and for those who don’t have reliable access to transportation to get to the centers.

After receiving Leqembi infusions for 18 months, some patients may have the option to begin maintenance treatment. This regimen may involve less frequent monthly infusions or self-administered injections at home. The FDA approved a weekly, self-injected maintenance version of Leqembi called LEQEMBI IQLIK in 2025. This subcutaneous (under the skin) option allows some patients to transition from IV infusions to an at-home regimen, which eliminates the need to travel to a hospital or other infusion center regularly.

Will Medicare cover Leqembi?

Since it was approved by the FDA, Medicare “broadly covers” Leqembi. However, certain conditions must be met first. Prescribing physicians must agree to enter patient information into a federal registry.⁸ The Centers for Medicare and Medicaid (CMS) hope this requirement encourages additional real-world data that ultimately will help the scientific community better understand how the drug works.

According to CMS, Medicare will cover Leqembi only for patients already enrolled in Medicare and who meet the FDA rules outlined under “Who can get Leqembi?” above.

How much does Leqembi cost?

Eiasi, Leqembi’s manufacturer, set the drug’s list price at $27,990 per year.⁹ “That’s still a lot of money,” said Vafiadis.

“What’s more, Medicare beneficiaries must still pay some out-of-pocket costs,” Vafiadis advised. That means patients will pay 20% of Leqembi’s cost after meeting their Part B deductible. It's something patients and caregivers need to consider before starting treatment."

Specifically, the out-of-pocket cost for Medicare enrollees will be $5,598 per year. For those with Medicare supplemental or other secondary insurance, the costs may be less. For someone enrolled in a Medicare Advantage plan, the out-of-pocket cost will vary, but could be as much as 20%.

As for Medicaid: it might cover Leqembi in some cases—without requiring the prescribing doctor to enter patient data into a federal registry. But it depends on where patients live and other factors. The best way to find out if Medicaid covers this Alzheimer’s treatment is to contact your state Medicaid office.

What about donanemab?

Another Alzheimer’s medication that targets amyloid proteins in the brain, donanemab (sold as Kisunla™) has shown promise in slowing functional and cognitive decline for people in early stages of the disease.¹⁰ This anti-amyloid treatment, which works similarly to Leqembi, received full traditional FDA approval for the treatment of early-stage Alzheimer's in 2024.

Phase 3 clinical trial results for donanemab, which were reported in July 2023, showed that the medication markedly slowed cognitive and functional decline in people with early symptomatic Alzheimer's disease. Nearly half (47%) of participants in the earliest stages of Alzheimer's who received donanemab had no clinical progression of the disease at one year.¹¹

While the clinical trial results were encouraging, donanemab carries the same safety concerns as lecanemab. Patients who take either drug must be monitored closely for brain swelling and bleeding. And neither drug has been tested long-term.

For more information on the latest treatments for Alzheimer’s, be sure to visit and bookmark NCOA’s Alzheimer's & Dementia resource page. 

Sources

1. Alzheimer’s Association. Treatments and Research. Found on the internet at https://www.alz.org/help-support/i-have-alz/treatments-research

2. BioSpace. CMS Expands Medicare Coverage for Leqembi After FDA Traditional Approval. Found on the internet at https://www.biospace.com/article/cms-expands-medicare-coverage-for-leqembi-after-fda-traditional-approval/

3. National Institute on Aging. What Happens to the Brain in Alzheimer’s Disease? Found on the internet at https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease

4. Jeffrey Cummings, et. al. Alzheimer’s disease drug development pipeline: 2022. Translational Research and Clinical Interventions, May 4, 2022. Found on the internet at https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/trc2.12295vestor.lilly.com/news-releases/news-release-details/results-lillys-landmark-phase-3-trial-donanemab-presented

5. Adam Feuerstein, et. al. FDA approves first Alzheimer’s therapy shown to clearly slow cognitive decline. STAT. July 6, 2023. Found on the internet at https://www.statnews.com/2023/07/06/leqembi-alzheimers-fda-approval-eisai-biogen/

6. Eisai Global. Results from Real-World, Long-Term Treatment Persistence with LEQEMBI® (lecanemab-irmb) in the United States Presented at AD/PD™ 2026. March 23, 2026. Found on the internet at https://www.eisai.com/news/2026/news202616.html

7. Alzheimer’s Association. Lecanemab approved for treatment of early Alzheimer’s Disease. Found on the internet at https://www.alz.org/alzheimers-dementia/treatments/lecanemab-leqembi

8. Centers for Medicare & Medicaid Services. Statement: Broader Medicare Coverage of Leqembi Available Following FDA Traditional Approval. Found on the internet at https://www.cms.gov/newsroom/press-releases/statement-broader-medicare-coverage-leqembi-available-following-fda-traditional-approval

9. Eisai. Lequembi Companion Patient Support Program: Understanding the cost of Lequembi. Found on the internet at https://www.leqembi.com/en/patient-support-program?tab=understand-the-cost

10. John R. Sims, et al. Donanemab in Early Symptomatic Alzheimer Disease: The TRAILBLAZER-ALZ 2 Randomized Clinical Trial. JAMA. July 27, 2023. Found on the internet at https://jamanetwork.com/journals/jama/fullarticle/2807533

11. Lilly Investors. Results from Lilly's Landmark Phase 3 Trial of Donanemab Presented at Alzheimer's Association Conference and Published in JAMA. July 17, 2023. Found on the internet at https://investor.lilly.com/news-releases/news-release-details/results-lillys-landmark-phase-3-trial-donanemab-presented