Lecanemab-irmb Injection
Lecanemab-irmb Injection is an amyloid beta-directed antibody used to treat Alzheimer’s disease in people with mild cognitive impairment or mild dementia, given by intravenous infusion or subcutaneous injection.
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The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
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Lecanemab-irmb (Leqembi) is a lab-made antibody that targets amyloid beta and shrinks the brain plaques of Alzheimer’s disease, a specialist drug for the mild cognitive impairment or mild dementia stage; on the U.S. market since about 2023, it modestly slows decline rather than stopping it. Doses are usually well tolerated, with headache or flu-like infusion reactions (fever, chills, nausea) the things people most often notice. The big concern is the boxed warning for ARIA, brain swelling or small bleeds that usually come early and silently but can be fatal, so ApoE ε4 gene testing, regular MRIs and prompt reporting of new confusion, vision changes or trouble walking all matter.
Clinical pearls
- If you ever have stroke-like symptoms, tell emergency staff you take Leqembi before any clot-busting drug is given.
- Tell every prescriber before starting a blood thinner, since anticoagulants may raise the risk of bleeding in the brain.
- Follow-up MRIs come at one, two, three and six months, since silent ARIA is usually caught only on the scan.
- The IQLIK autoinjector allows weekly injections under the skin instead of infusions, and your prescriber can switch between routes.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Leqembi can cause ARIA, which is swelling or small bleeding in the brain. It can sometimes be serious, life-threatening, or fatal.
ARIA usually appears early in treatment and often causes no symptoms, so it is found by MRI. Symptoms, when they occur, can include headache, confusion, vision changes, dizziness, nausea, and trouble walking. Larger brain bleeds (over 1 cm) have also occurred.
People with two copies of the ApoE ε4 gene (about 15% of people with Alzheimer’s disease) have a higher risk of ARIA, including serious cases. Testing for this gene is recommended before starting. You can still be treated without testing, but your risk level will not be known.
ARIA swelling can look like a stroke. Doctors should consider ARIA before giving clot-busting drugs to someone taking Leqembi. You and your prescriber should weigh the benefit against the risk before starting.
Patient information guide — a plain-language walkthrough of Lecanemab-irmb Injection, written from its FDA label.
What Lecanemab-irmb Injection is used for
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Lecanemab-irmb treats Alzheimer’s disease.
- Leqembi is for Alzheimer’s disease in people with mild cognitive impairment or mild dementia.
- Leqembi vials are given by IV infusion.
- Leqembi IQLIK autoinjector is given by subcutaneous injection.
How Lecanemab-irmb Injection works
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Lecanemab-irmb is a monoclonal antibody that binds to amyloid beta, a protein that forms plaques in the brain in Alzheimer’s disease. By targeting both soluble and insoluble forms, it reduces amyloid plaques in the brain.
Lecanemab-irmb Injection dosage
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Leqembi is given by IV infusion (vials, diluted first) or by subcutaneous injection (IQLIK autoinjector). Both routes have a starting schedule and, after 18 months, a possible maintenance schedule. Your prescriber can switch routes using timing set out on the label.
- IV: infusion over about an hour, every 2 weeks at first, then possibly every 4 weeks.
- Subcutaneous: injection once a week.
- MRI scans are done before starting and after 1, 2, 3, and 6 months.
Follow your prescriber and the label for exact doses and what to do about missed doses.
Dosing details from the FDA-approved label
From the Lecanemab-irmb Injection prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Starting dosage regimen, intravenous (LEQEMBI)
- 10 mg/kg once every 2 weeks, administered after dilution as an intravenous infusion over approximately one hour
- Calculated from the patient's actual body weight; diluted in 250 mL of 0.9% Sodium Chloride Injection, USP
- Starting dosage regimen, subcutaneous (LEQEMBI IQLIK)
- 500 mg (two 250 mg injections) once every week using the LEQEMBI IQLIK autoinjector
- After 18 months, continue the starting dosage or transition to a maintenance dosage
- Maintenance dosage regimen, intravenous (LEQEMBI)
- 10 mg/kg once every 4 weeks, over approximately one hour
- First maintenance dose 2 weeks after last intravenous starting dose; if previously on subcutaneous starting regimen, minimum of 2 weeks but no more than 3 weeks
- Maintenance dosage regimen, subcutaneous (LEQEMBI IQLIK)
- 360 mg once every week using the LEQEMBI IQLIK autoinjector
- First maintenance dose 1 week after last starting dose, regardless of starting dosage regimen
- Switching route during starting or maintenance regimen: intravenous to subcutaneous
- Administer the first subcutaneous dose 1 week after the last intravenous dose
- Switching route during starting regimen: subcutaneous to intravenous
- Administer the first intravenous dose a minimum of 2 weeks, but no more than 3 weeks, after the last subcutaneous dose
- Switching route during maintenance regimen: subcutaneous to intravenous
- Administer the first intravenous dose 1 week after the last subcutaneous dose
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Confirm the presence of amyloid beta pathology prior to initiating treatment. ( 2.1 ) Obtain a recent baseline brain MRI prior to initiating treatment. ( 2.4 , 5.1 ) Obtain an MRI after 1, 2, 3, and 6 months of treatment. If radiographically observed ARIA occurs, treatment recommendations are based on type, severity, and presence of symptoms. ( 2.4 , 5.1 ) Recommended starting dosage: Intravenous infusion: 10 mg/kg once every 2 weeks administered after dilution as an intravenous infusion over approximately one hour. ( 2.2 , 2.5 ) Subcutaneous injection: 500 mg administered once a week using the LEQEMBI IQLIK autoinjector. ( 2.2 , 2.6 ). After 18 months, continue treatment with the starting dosage or transition to an intravenous or subcutaneous maintenance dosage. (2.2) Recommended maintenance dosage: Intravenous infusion: 10 mg/kg once every 4 weeks ( 2.2 , 2.5 ) Subcutaneous injection: 360 mg administered once a week using the LEQEMBI IQLIK autoinjector ( 2.2 , 2.6 ). See Full Prescribing Information for preparation and administration instructions. ( 2.5 , 2.6 ) 2.1 Patient Selection Confirm the presence of amyloid beta pathology prior to initiating treatment [see Clinical Pharmacology ( 12.1 )] . 2.2 Recommended Dosage Initiate LEQEMBI using a starting dosage regimen (see Table 1 ). After 18 months, the starting dosage regimen may be continued or a transition to a maintenance dosage regimen may be considered (see Table 2 ). Both the starting and maintenance dosage regimens can be administered by either intravenous infusion or subcutaneous injection. The route of administration can be switched. When switching the route of administration and simultaneously transitioning from the starting dosage regimen to the maintenance dosage regimen, see Table 2. When switching the route of administration during the starting dosage regimen or during the maintenance dosage regimen, see Dosage and Administration ( 2.3 ).
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Lecanemab-irmb Injection side effects
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Common side effects
- Infusion-related reactions (fever, flu-like symptoms, nausea)
- Injection-related reactions with subcutaneous use
- ARIA-microhemorrhages (tiny spots of bleeding in the brain seen on MRI)
- ARIA-edema/effusion (brain swelling or fluid seen on MRI)
- Headache
When to get medical help
- Get help right away for sudden confusion, vision changes, dizziness, severe headache, nausea, trouble walking, or seizures, which can be signs of ARIA.
- Seek emergency care for stroke-like symptoms, such as weakness or trouble speaking. Tell emergency staff you take Leqembi before any clot-busting drug is given.
- Get help for signs of a serious allergic reaction, such as swelling of the face or throat, wheezing, or trouble breathing.
- Tell your care team about fever, chills, aches, shakiness, or breathing trouble during or after a dose.
The most common side effects are:
- Infusion-related reactions
- Injection-related reactions with the subcutaneous form
- ARIA-microhemorrhages
- ARIA-edema/effusion
- Headache
Call your doctor right away for confusion, vision changes, severe headache, trouble walking, seizures, or signs of allergic reaction.
Lecanemab-irmb Injection warnings and precautions
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- ARIA (brain swelling or bleeding) can be serious or fatal. It is most likely in the first 14 weeks and in people with two ApoE ε4 copies.
- Brain bleeds over 1 cm have occurred, some fatal.
- Risk is higher with earlier microhemorrhages or superficial siderosis on MRI.
- Serious allergic reactions, including angioedema and anaphylaxis, can occur.
- Infusion-related reactions are most common with the first infusion.
Lecanemab-irmb Injection interactions
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Take extra care with these medicines:
- Blood thinners: higher chance of brain bleeding.
- Clot-busting drugs: ARIA can mimic a stroke, and a fatal bleed has occurred in this drug class.
- Aspirin and other antiplatelets: did not increase ARIA in studies, but tell your prescriber.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Lecanemab-irmb Injection
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- Do not use if you had a serious allergy to lecanemab-irmb or its ingredients.
- Get a baseline brain MRI and ApoE ε4 testing discussion first.
- Tell your prescriber about prior brain bleeds or MRI findings suggesting cerebral amyloid angiopathy.
- Pregnancy data are inadequate.
- Breastfeeding data are lacking; discuss with your prescriber.
- Not established in children.
- No overall differences were seen in people 65 and older.
What Lecanemab-irmb Injection does in the body
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Lecanemab-irmb lowers amyloid beta plaque in the brain, measured by PET imaging. In studies the reduction grew over time compared with placebo.
How your body processes Lecanemab-irmb Injection
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Levels reach steady state after about 6 weeks of IV dosing every 2 weeks. After subcutaneous autoinjector use, about 77.5% (higher dose) and 53% (lower dose) is absorbed, regardless of injection site (abdomen, upper thigh, or upper arm). The body breaks it down like natural antibodies, with a half-life of 5 to 7 days. It is not expected to be cleared by the kidneys or processed by liver enzymes.
How to store Lecanemab-irmb Injection
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Store LEQEMBI vials in a refrigerator at 2°C to 8°C (36°F to 46°F). Store in the original carton to protect from light. Do not freeze or shake.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Lecanemab-irmb Injection: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Lecanemab-irmb Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What is Leqembi used for?
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How will I receive it?
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Why do I need so many MRIs?
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What side effects should I expect, and when should I call?
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Does my gene test matter?
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Can I take it with blood thinners?
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Is Lecanemab-irmb Injection available over the counter?
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When was Lecanemab-irmb Injection first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Lecanemab-irmb Injection on HelloPharmacist
Lecanemab-irmb Injection forms and strengths (how it comes)
Lecanemab-irmb Injection is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Injection
How this form is used
- Leqembi is used to treat Alzheimer’s disease in people with mild cognitive impairment or mild dementia.
- Leqembi IQLIK autoinjector is the subcutaneous form of Leqembi.
- Leqembi vials are diluted and given as an IV infusion over about one hour.
- Leqembi IQLIK is given as a subcutaneous injection once a week.
- Leqembi can be switched between IV and subcutaneous routes, following the label timing.
Lecanemab-irmb Injection on the U.S. market: products, makers and brands
How Lecanemab-irmb Injection appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
1 company lists 4 Lecanemab-irmb Injection product records with the FDA, mostly as injection; the earliest marketing or approval year on record is 2023. Brand names on the directory include Leqembi, Lecanemab Autoinjector; the rest are generics.
Compare Lecanemab-irmb Injection products
A representative set of FDA-listed product records for Lecanemab-irmb Injection — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 100 mg/mL | Intravenous | Eisai Inc. × 2 listings | BLA | View NDC → |
| 200 mg/mL | Subcutaneous | Eisai Inc. × 2 listings | BLA | View NDC → |
Showing 4 of 4 products — FDA National Drug Code Directory. See every product, package size and price: browse all 4 Lecanemab-irmb Injection NDCs →
Lecanemab-irmb Injection side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Lecanemab-irmb Injection — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Lecanemab-irmb Injection in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Lecanemab-irmb Injection FDA approval history
How Lecanemab-irmb Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Lecanemab-irmb Injection recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Lecanemab-irmb recalls since July 2021.
✅No Lecanemab-irmb recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
Lecanemab-irmb Injection supply and shortage status
Whether Lecanemab-irmb Injection is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Lecanemab-irmb Injection brand names
Lecanemab-irmb Injection is sold under 2 brand names in the FDA directory — Leqembi, Lecanemab Autoinjector. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Lecanemab-irmb Injection: manufacturers and labelers
One company lists Lecanemab-irmb Injection products with the FDA. By number of product records, the largest are Eisai Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Lecanemab-irmb Injection drug class (RxNorm)
Lecanemab-irmb Injection belongs to the Amyloid Beta-directed Antibody class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Lecanemab-irmb Injection page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Eisai Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →