Leqembi IQLIK and IV Leqembi are two delivery methods of the same Alzheimer's drug (lecanemab), not separate medications; the main differences lie in how often you receive it and which side effects are most common. IV Leqembi, approved by the FDA in 2023, requires biweekly infusions for 18 months followed by monthly infusions for maintenance, while Leqembi IQLIK—the subcutaneous (under-the-skin) version—uses weekly self-injections and became available for initiation in late August 2026. The choice between them hinges on tolerability, convenience, and whether you've already completed the IV initiation phase.
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
- How Dosing Schedules Differ
- Safety and Tolerability—The Critical Difference
- APOE4 Genotype and Eligibility
- Current Availability and Timeline
- Transitioning Between Formulations
- Frequently Asked Questions
How Dosing Schedules Differ
IV Leqembi delivers 10 mg/kg intravenously every two weeks for the first 18 months, then switches to one infusion every four weeks for ongoing maintenance. Leqembi IQLIK subcutaneous initiation uses 500 mg weekly (delivered as two 250 mg injections via autoinjector, each taking about 15 seconds), with the same 18-month initiation window before transitioning to 360 mg weekly maintenance dosing.
The cumulative drug exposure is comparable; the difference is in frequency and route. IV patients must visit a clinic every two weeks, while IQLIK patients can self-inject at home weekly.
Safety and Tolerability—The Critical Difference
The most significant distinction emerges in systemic (whole-body) reactions: subcutaneous Leqembi causes systemic reactions in fewer than 1% of patients, compared to 26% for the IV formulation. This means IV infusions trigger fever, chills, nausea, or joint pain in roughly one in four patients, while SC injections rarely provoke these systemic responses.
However, IQLIK introduces local injection-site reactions—redness, swelling, induration, rash, and pain at the injection site—and occasionally delayed reactions that appear days after an injection. Both formulations carry comparable risk of amyloid-related imaging abnormalities (ARIA), a form of brain swelling or microhemorrhages detected on MRI. The choice hinges on preference: tolerate fewer but predictable systemic symptoms (IV) or manage local injection reactions and self-inject weekly (IQLIK).
APOE4 Genotype and Eligibility
Before starting either formulation, your APOE genotype—a genetic marker tied to dementia risk—affects efficacy and risk. The FDA label does not restrict lecanemab by APOE status, but the European Medicines Agency does: approval is limited to patients carrying 0 or 1 APOE ε4 allele.
In practical terms, patients who are APOE ε4 homozygotes (two copies) show poor response to the drug and higher ARIA risk in trials. Ask your neurologist whether APOE testing is recommended before initiation—it may inform the decision to treat with either formulation.
Current Availability and Timeline
IV Leqembi received FDA traditional (full) approval in July 2023 and is widely available through infusion centers. Leqembi IQLIK for initiation became available in late August 2026, making it the newer option for patients starting treatment. Access depends on your insurance, whether your neurologist can prescribe it, and drug supply—call your provider to confirm current availability.
Transitioning Between Formulations
Patients who began on IV infusions can transition to IQLIK maintenance (360 mg weekly) after 18 months of IV or prior SC treatment. Those starting new in late 2026 can begin directly with IQLIK weekly injections, skipping the clinic infusion route entirely. Your neurologist will manage the switch; the timing is fixed at the 18-month mark.
Frequently Asked Questions
Can I switch from IV to IQLIK before 18 months?
Current prescribing guidance does not support switching before 18 months of initiation therapy; the transition to 360 mg weekly SC maintenance occurs after the 18-month IV or SC initiation phase ends.
Do I need an APOE4 test before starting?
Ask your neurologist. The FDA does not restrict treatment based on APOE4 status, but knowing your genotype may influence risk–benefit discussion, especially if you are homozygous (two ε4 alleles).
Which formulation should I choose if I'm starting now?
If you have a strong preference for weekly self-injections and dislike clinic visits, IQLIK initiation is available as of late August 2026. If you prefer expert supervision and tolerate systemic side effects, IV remains widely available and establishes a longer track record.
