Are the Side Effects of Lecanemab Manageable?
When the U.S. Food and Drug Administration approved Lecanemab in 2023, it marked a turning point in Alzheimer’s treatment. For the first time, a medication had shown it could modestly slow the progression of the disease — a long-awaited development in dementia research.
Understandably, the approval was met with hope and enthusiasm. But it also raised questions.
In particular, many people were concerned about reports of side effects like brain swelling and bleeding that had emerged during clinical trials. For some, these risks were enough to hesitate — or avoid treatment altogether.
So what’s the real picture?
What New Research Says About Lecanemab’s Safety
A recent study from Washington University School of Medicine in St. Louis aimed to provide real-world answers. Researchers studied the adverse effects of Lecanemab in patients treated at their own clinic — outside the controlled environment of a clinical trial.
Their findings?
Serious side effects were rare, and most patients tolerated the treatment well.
Here’s what they found:
Only 1% of patients experienced severe side effects that required hospitalisation.
Patients in the earliest stages of Alzheimer’s (with very mild symptoms) had the lowest risk of complications (just 1.8%).
Those with mild Alzheimer’s had a higher risk (up to 27%), showing the importance of early treatment.
How Is Lecanemab Given?
Lecanemab is delivered via infusion every two weeks, under medical supervision.
Importantly, patients are also closely monitored with sophisticated brain imaging tools. These scans help doctors detect any early signs of swelling or bleeding, often before symptoms appear — allowing intervention if needed.
This level of ongoing monitoring makes the treatment safer and more responsive.
Is It Worth It?
Like all treatments, Lecanemab carries some risk — but this study shows that in the right patients, with the right monitoring, those risks are low and manageable.
For many, the bigger risk may actually be in waiting too long.
Delaying treatment can lead to disease progression, which in turn increases the chance of complications if the medication is started later. The study supports what many experts already believe: starting Lecanemab early is key to maximising benefit and minimising risk.
The Bottom Line
Lecanemab offers real hope for slowing Alzheimer’s — particularly in its earliest stages. And while side effects like brain swelling and bleeding sound frightening, the latest research shows they’re rare, manageable, and less likely when treatment is started early.
If you or someone you love has received an early Alzheimer’s diagnosis and you’re considering treatment options, it’s worth discussing Lecanemab with your doctor — especially now that we have more real-world safety data.
