At-home lecanemab injections mean a caregiver or patient now handles a step that used to happen only in a clinic, so a checklist has to cover what the infusion team used to catch automatically. The core task is pairing every weekly injection with the MRI schedule, genetic risk awareness, and symptom checks that the drug's safety data require. Lecanemab (brand name Leqembi) is an anti-amyloid antibody for early Alzheimer's disease. In late August 2025 the FDA approved Leqembi IQLIK, a once-weekly subcutaneous autoinjector for maintenance dosing, which launched in the US on October 6, 2025 as the first at-home anti-amyloid Alzheimer's treatment.
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
- Who qualifies for the at-home injection, and how is it given?
- The MRI schedule caregivers need to track
- Know the ApoE ε4 status before starting
- Symptoms that mean call the clinic now
- What the injection site itself should look like
- Frequently Asked Questions
Who qualifies for the at-home injection, and how is it given?
The autoinjector is not a starting dose. Patients must first complete 18 months of biweekly IV lecanemab at 10 mg/kg before switching to the weekly 360 mg/1.8 mL subcutaneous dose, which takes about 15 seconds to administer. The prescribing information allows injection into the abdomen, the upper thigh, or the back of the upper arm, with the arm site generally reserved for a caregiver rather than self-injection.
The injection must avoid moles, scars, bruises, tattoos, and any skin within about 2 inches of the navel, according to the Instructions for Use. Before anyone self-injects or gives the injection to a loved one, a prescriber or trained staff member must demonstrate correct autoinjector technique in person. That same prescriber is required to periodically check that the patient or caregiver can still perform the injection safely, per the FDA label's Instructions for Use.
The MRI schedule caregivers need to track
Lecanemab carries an FDA boxed warning for ARIA — amyloid-related imaging abnormalities — which shows up on brain MRI as either swelling (ARIA-E) or small bleeds and hemosiderin deposits (ARIA-H). The FDA label states that serious intracerebral hemorrhages over 1 cm have occurred, some fatal, and that ARIA itself can be fatal. A baseline brain MRI within the year before starting treatment is required.
In August 2025 the FDA updated the label's monitoring schedule (Section 2.3) to add an earlier MRI between the 2nd and 3rd infusions, on top of the MRIs already required before the 5th, 7th, and 14th doses, according to the FDA's drug safety communication. A practical scheduling note: these MRIs are tied to dose number, not calendar date, so a missed or delayed infusion shifts every MRI after it. Keeping a written log of dose number alongside each completed scan is the simplest way to avoid losing track once injections move from clinic visits to a weekly routine at home.
Know the ApoE ε4 status before starting
ApoE ε4 is a gene variant linked to Alzheimer's risk, and patients who inherit two copies (homozygotes) make up about 15% of those with the disease. This group faces a higher rate of symptomatic, serious, and severe ARIA, which is why the FDA label recommends ApoE ε4 genotyping before treatment begins.
For a caregiver, the genotype result changes how closely symptoms need to be watched, not whether treatment can proceed. A patient who tests as ε4 homozygous warrants a lower threshold for calling the prescriber about any new headache, confusion, or vision change, since that group's ARIA risk profile is measurably higher than non-carriers or single-copy carriers.
Symptoms that mean call the clinic now
Roughly 75–80% of ARIA cases show no symptoms at all and turn up only on a scheduled MRI, per the FDA label. That makes the scheduled scans in Section 2 the primary safety net — but symptomatic ARIA still needs to be recognized immediately when it happens. The symptoms to watch for are headache, confusion, dizziness, nausea, and visual disturbance, according to the UK patient leaflet and the FDA label.
Clinical vigilance matters most in the first 14 weeks of treatment, when ARIA risk is highest. One detail specific to emergency settings: focal neurologic deficits from ARIA-E can look like a stroke. Clinicians are instructed to rule out ARIA-E before giving stroke clot-busting drugs (thrombolytics), so a caregiver bringing a patient to an ER should say clearly that the patient is on lecanemab and when the last dose and last MRI occurred.
What the injection site itself should look like
Localized injection-site reactions — pain, redness, or itching at the spot — are the most common side effect of the subcutaneous form, occurring in about 11% of patients in clinical study. Systemic reactions affect under 1% of patients, both rates markedly lower than with the IV infusion version, per clinical trial data cited by epocrates.
Rotating injection sites between the abdomen, thigh, and upper arm each week, and avoiding the same exact spot twice in a row, keeps local irritation from building up at one location. A site that stays red, swollen, or painful for more than a day or two — rather than settling within hours — is worth mentioning at the next check-in rather than waiting for the next scheduled MRI visit.
Frequently Asked Questions
Can a patient start directly on the at-home injection without IV infusions first?
No. The autoinjector is approved only as maintenance dosing after 18 months of biweekly IV lecanemab infusions.
Does genotyping change how often MRIs are needed?
No, the MRI schedule (baseline, then before doses 2-3, 5, 7, and 14) applies to all patients; ApoE ε4 homozygotes simply carry a higher risk of symptomatic ARIA during that same schedule.
Who has to train a caregiver to give the injection?
A prescriber or trained staff member must demonstrate the autoinjector in person before the first caregiver-given dose and must periodically reassess that the caregiver can still do it safely.
