Day-one subcutaneous Leqembi (lecanemab-irmb), a drug that removes brain amyloid linked to Alzheimer's, lets eligible adults with early disease start treatment with weekly shots at home in 2026. Adult children can prepare by confirming eligibility, arranging gene counseling and brain scans, learning injections, and checking Medicare registry rules. Eisai and Biogen announced FDA approval for subcutaneous starting on July 13, 2026, as the first anti-amyloid therapy usable under the skin from day one, according to the Eisai and Biogen press release. The starting dose is 500 mg weekly as two 250 mg autoinjector shots of about 15 seconds each, with 360 mg weekly as maintenance after 18 months.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Is your parent eligible?
- What does home treatment involve?
- How do you watch for brain swelling and bleeding?
- What gene test and coverage steps come first?
Is your parent eligible?
Treatment is only for mild cognitive impairment or mild dementia due to Alzheimer's with confirmed amyloid by PET scan or spinal-fluid test, the Alzheimer's Association treatment page states. Moderate or severe dementia does not qualify.
Ask the neurologist which stage and which amyloid test is in the chart. Get copies of the diagnosis note and amyloid result. Clinics and insurers will ask for both.
- early memory or thinking change tied to Alzheimer's, not another cause
- amyloid confirmed by PET or cerebrospinal fluid testing
- mild impairment or mild dementia only
- clinician review of other brain-bleed risks
What does home treatment involve?
A parent or caregiver can give the weekly shots at home after training. A clinician can also direct a switch between vein infusion and skin injection. Home dosing removes the need to start in an infusion center.
Practice the routine in the clinic: room-temperature pens, two shots in a row, skin check, and disposal. Keep a weekly log with date, site, missed doses, and side effects. Ask who to call nights and weekends.
How do you watch for brain swelling and bleeding?
Leqembi carries an FDA boxed warning for amyloid-related imaging abnormalities with swelling (ARIA-E) and bleeding (ARIA-H), which can be serious or fatal and need urgent care, according to the FDA prescribing information. Call promptly for headache, confusion, vision change, dizziness, or trouble walking. Do not wait for the next scan.
The FDA label calls for a recent brain MRI before starting plus scans after about 1, 2, 3, and 6 months. Book those scans before the first shot. Families must plan repeat trips for imaging even with home dosing.
What gene test and coverage steps come first?
APOE-e4 gene testing and counseling come before treatment because two copies raise ARIA risk sharply. Reported rates are about 45% in double carriers versus about 13% in noncarriers, with added risk from prior tiny bleeds or surface iron deposits. Use the result to discuss benefits, burdens, and monitoring.
Medicare covers IV lecanemab under Part B only through Coverage with Evidence Development, per a LegalClarity summary of the CMS policy. That path requires early-disease diagnosis, amyloid proof, and enrollment of patient and prescriber in a CMS-approved registry with follow-up reports. Ask the prescribing clinic which registry it uses and who files the reports before you leave the first visit.
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