Not medical advice — written by Ngoc Vietsmall, who is not a healthcare professional.
This article summarises publicly available medical information for general readers. It cannot account for your history, medication or symptoms, and it is not a diagnosis or a treatment plan. Any dose mentioned comes from published labelling or guidelines — only your own prescriber can decide what is right for you.
Always speak to a doctor or pharmacist before starting, stopping or changing any treatment. If symptoms are severe or getting worse, seek urgent care. Full disclaimer · How this is written
Leqembi is usually given every two weeks for about 18months, after which many patients stay on the same plan or shift to a oncemonthly infusion. Below youll find the full timeline, dosing details, what to expect during each visit, and how to keep an eye on safety. Think of this as a friendly roadmap that helps you feel confident about every step of the treatment.
Treatment Duration
What does the official labeling say?
The FDAs label recommends a dose of 10mg per kilogram of body weight every two weeks for 18months. After that period, patients may continue on the same schedule or move to a maintenance infusion every four weeks, depending on how theyre doing and what their neurologist advises.[source]
Why 18months?
Clinical trials showed that an 18month course provides the most consistent reduction in amyloid plaques and slows cognitive decline. The data comes from the ClarityAD study, which followed participants for a bit longer than a year and a half. In short, the brain needs that amount of time to reset its plaque load.
Can the course be longer or shorter?
Yesrealworld practice is flexible. Some doctors extend therapy beyond 18months if the patient tolerates it well and continues to benefit. Others may stop earlier if sideeffects become a problem or if the disease progresses despite treatment. Always discuss the timing with your specialist; theyll weigh the benefits against any risks.
Timeline Graphic (example)
| Month | Infusion Frequency | Key Monitoring |
|---|---|---|
| 018 | Every 2weeks | Baseline MRI, labs before each infusion |
| 1924 | Every 4weeks (optional) | Followup MRI at 6month intervals |
| 25+ | Physicianguided | Continued labs, symptom check |
Infusion Protocol
How often are infusions administered?
During the first 18months, youll head to the infusion center every two weeks. If you switch to maintenance, the visits become once a montha noticeable drop in the calendar.
How long does each infusion take?
Most sessions last about one hour. The drug itself is administered over roughly 30minutes, followed by a short observation period to make sure there are no immediate reactions.
What should I plan for on infusion day?
Bring a list of current medications, a snack, and something to keep you occupied (a book, a crossword, or your favorite playlist). Youll sit comfortably, have a quick vitals check, and then the nurse will start the drip. After the infusion, theres a 30minute monitoring window before youre cleared to go.
Is there a longer firstinfusion slot?
Yes, the very first visit often includes extra paperwork, insurance verification, and a more thorough baseline assessment. It can feel like a minimarathon, but its just one dayand it sets the stage for smoother visits later.
InfusionDay Checklist
- Bring insurance card and medication list
- Wear comfortable clothing (short sleeves help with IV access)
- Arrive 10minutes early for registration
- Stay hydrated (but follow any fasting instructions)
- Plan a light snack for after the visit
Dosage Tools
How is the dose determined?
Leqembis dose is weightbased: 10mg per kilogram of body weight. So a person who weighs 70kg receives 700mg per infusion, while an 85kg individual gets 850mg.
What if Im 70kg vs. 85kg?
Heres a quick comparison:
| Weight (kg) | Dosage (mg) |
|---|---|
| 70 | 700 |
| 75 | 750 |
| 80 | 800 |
| 85 | 850 |
Leqembi dosing calculator where to find it?
The drugs manufacturer provides a free online calculator that lets you plug in your weight and instantly see the exact milligram amount. You can also download a printable worksheet to keep on your fridge.
Do I need dose adjustments for kidney or liver issues?
Current guidance suggests no routine adjustments for mild renal or hepatic impairment, but severe disease may warrant a conversation with your doctor. Always let your care team know about any organfunction concerns before each infusion.
Downloadable Dosing Worksheet
Take a moment to jot down your weight, the calculated dose, and the next appointment date. Seeing everything on paper makes the schedule feel less abstract.
Monitoring Schedule
What MRI schedule is recommended?
A baseline MRI is performed before the first infusion. Followup scans are typically ordered at 6month intervals to watch for amyloidrelated imaging abnormalities (ARIA) and to gauge plaque clearance.
Why are MRIs needed?
Leqembi works by clearing amyloid plaques, but that process can occasionally cause temporary swelling or microhemorrhageswhat researchers call ARIA. Regular imaging helps catch these changes early so you can adjust treatment if needed.
What labs are checked before each infusion?
Standard labs include a complete blood count (CBC), liver enzymes, and renal function tests. These numbers ensure your body can safely handle the medication and help spot any emerging issues.
Monitoring Timeline
- Baseline MRI + labs (Week0)
- Every 2weeks: CBC, liver & kidney panels
- Every 6months: MRI + clinical assessment
- After 18months: Reevaluate schedule & imaging frequency
Benefits vs Risks
What are the proven benefits of staying on therapy for 18months?
Patients who complete the 18month course show a slower rate of cognitive decline on standard tests (like the ADASCog) and tend to retain more dailyliving independence than those who stop early. The effect isnt a cure, but it can buy valuable time.
Common sideeffects & how to manage them
Most people experience mild infusionrelated reactions: a brief headache, nausea, or a feeling of lightheadedness. Drinking water, having a light snack beforehand, and lying down for a few minutes after the infusion usually eases these symptoms.
Serious adverse events to watch
The biggest concern is ARIA, which can cause headache, visual changes, or confusion. If you notice any new neurological symptoms, call your neurologist right away. In most cases, ARIA resolves on its own or with a temporary pause in dosing.
How does the riskbenefit balance change after 18months?
Longterm data beyond the trial period is still emerging. Some clinicians report continued benefit, while others pause therapy to reassess safety. This uncertainty reinforces why regular checkins with your specialist are crucial.
Pros & Cons Comparison
| Pros | Cons |
|---|---|
| Slower cognitive decline | Infusion schedule (every 24 weeks) |
| Potential for maintained independence | Possible ARIA or infusion reactions |
| Wellstudied 18month protocol | Limited longterm data beyond 18 months |
Key Questions
How many infusions of Leqembi are needed?
During the standard 18month period youll receive roughly 36 infusions (biweekly). Maintenance adds one more every month if you continue.
Can I stop after 12months?
Stopping early may reduce the medications effectiveness, so any change should be made after a thorough discussion with your doctor.
What if I miss an infusion?
Contact your infusion center ASAP. Usually you can reschedule within a week, but the dosing interval may need a small adjustment to keep drug levels stable.
Is Leqembi covered by insurance?
Most Medicare Advantage plans and many private insurers cover Leqembi, but they often require prior authorization. Your clinics billing staff can help you navigate the paperwork.
How does Leqembi work?
Leqembi is a monoclonal antibody that binds to aggregated amyloid plaques, helping the brains immune system clear them. By reducing plaque burden, it slows the cascade of neurodegeneration that drives Alzheimers disease.
Next Steps
Key questions to ask your neurologist
Before your next appointment, consider writing down:
- What is the exact duration you recommend for my case?
- Should I aim for the biweekly or monthly schedule after 18months?
- What specific labs and imaging will I need, and how often?
- How will we monitor for ARIA, and what should I do if symptoms appear?
- What are the options if sideeffects become challenging?
Preparing for your first infusion
Gather your insurance card, a current medication list, and a light snack. Bring a friend or family member for moral support, especially if youre nervous about IV placement. The staff will walk you through each step, and a short postinfusion observation period ensures you leave feeling safe.
When to consider switching or stopping therapy
If you notice a steady decline despite treatment, or if serious sideeffects emerge, discuss alternative options with your doctor. The decision is personal and should balance quality of life, symptom progression, and your own comfort level.
Helpful Resources
The Alzheimers Association offers patientfocused guides on navigating infusion therapies and provides support groups for families. Their materials can be a great supplement to the medical advice you receive.[source]
Conclusion
Leqembi is typically taken for 18months on a biweekly schedule, after which many patients either continue with the same plan or shift to a monthly infusion. Knowing your weightbased dosage, keeping up with MRI and lab monitoring, and staying aware of both benefits and sideeffects empower you to make informed decisions. Talk openly with your neurologist, use the dosing calculator, and lean on trusted resourcesyoure not alone on this journey.
