6 Aduhelm Side Effects You Should Know About

Aduhelm (aducanumab) garnered a lot of excitement with its FDA approval back in June 2021. It was the first new Alzheimer’s disease medication to be approved in almost two decades. It’s also a first-of-its-kind medication. It targets the underlying pathway of this memory-threatening disease instead of just its symptoms.

At the same time, Aduhelm’s approval has been controversial. After all, it was approved based on a surrogate endpoint. This is a marker that predicts — but doesn’t show — that Aduhelm can slow down Alzheimer’s disease. The manufacturer still must complete clinical trials to confirm Aduhelm’s benefits in order for the medication to stay on the market.

If you or a loved one have Alzheimer’s, you might wonder if Aduhelm could be a possible treatment option. Perhaps a top concern is how this medication’s side effects might impact your life. Below, we’ll discuss the top six Aduhelm side effects you should know about.

1. Brain swelling and small brain bleeds

The most common Aduhelm side effects involve problems in the brain. They’re called amyloid-related imaging abnormalities (ARIA). Most of the time, ARIA won’t cause noticeable symptoms. Signs of ARIA are usually only found through magnetic resonance imaging (MRI) brain scans. There are two types of ARIA:

1. ARIA-E. “E” for edema, ARIA-E is a type of swelling in the brain caused by a buildup of fluid.

2. ARIA-H. “H” for hemorrhage, ARIA-H involves small bleeds inside the brain.

In clinical trials of people who received monthly Aduhelm infusions, researchers found at least one type of ARIA in 41% of people taking Aduhelm (compared to 10% of people who received placebo). Among this 41%, more people had ARIA-E (35%) than ARIA-H (up to 19%).

For many study participants, ARIA signs were detected within their first 8 infusions. And in most cases, they resolved on their own within 5 months. ARIA doesn't seem to be a long-term problem for most people.

If you take Aduhelm, you’ll need to get an MRI before you start it. And once you begin monthly infusions, you’ll need to get MRIs every few months to check for ARIA. If you develop ARIA, your healthcare provider might stop or pause your Aduhelm treatments depending on the severity of the ARIA and whether you have any noticeable symptoms.

Even though most people with ARIA don’t feel symptoms, at least 24% of people did in clinical trials. We’ll discuss those symptoms below.

2. Headaches

Headaches are another common side effect of Aduhelm. They can be quite bothersome and make it hard for you to get through the day. About 21% of people who took Aduhelm in clinical trials reported various types of headaches, ranging from head discomfort and migraines to sharp nerve pain.

If you experience headaches of any kind while receiving Aduhelm, let your healthcare provider know. It’s better to check in with them instead of trying to self-treat it with over-the-counter medications. They might schedule an MRI for you to look for signs of ARIA. 

If your provider notices any changes on the scans, they may stop or pause your treatment. Depending on how severe it is and if it goes away on its own, your healthcare provider might restart Aduhelm for you.

3. Confusion

It can be scary to suddenly not remember where you are or have trouble talking to others. But confusion, feeling disoriented, and delirium are possible side effects of Aduhelm. They were reported by 8% of people who received Aduhelm in clinical trials.

These symptoms can be alarming because they can mimic symptoms of Alzheimer’s disease itself. So it might be difficult to tell whether you’re experiencing side effects of Aduhelm or if your condition is getting worse.

Make sure to let your healthcare provider know right away if you notice that you or your loved one are feeling more confused, forgetful, or sleepy. They’ll want to check to see how you’re doing and might want to do a brain scan to look for an underlying cause.

4. Higher risk for falling down

Aduhelm may also increase the risk of falls. Falls might be related to dizziness or changes in vision that some people experience with the medication. Your risk might be higher if you’re taking medications that also raise your risk for falls, such as certain antidepressants or blood pressure medications.

Falls can be debilitating if they happen. They might lead to serious injuries, such as broken bones and head injuries. Older adults can have a particularly difficult time recovering from these injuries — they can lead to longer hospital stays and loss of independence.

Before you start receiving Aduhelm, you might want to consider a home fall risk assessment if you haven’t already done so. A healthcare professional can help you spot the fall risks in your home and make changes to ensure your home’s safety. You might also want to look into getting a medical alert system with fall detection so you can get the emergency help you need.

If you experience a fall, you should seek medical attention right away. Your provider can check to see if you have any injuries, especially those inside your body, that need immediate care. 

5. Nausea

Nausea isn’t a very common side effect of Aduhelm, but it’s possible. It was reported by 2% of people with ARIA during clinical trials.

If you feel nauseous after starting Aduhelm, talk with your healthcare provider. It may or may not be related to ARIA, so they might order brain scans to check for it. They can also offer other tips for getting your nausea under control.

6. Diarrhea

Aduhelm can cause diarrhea. Infectious diarrhea is also possible, but it’s less common. It can be accompanied by symptoms like fever, vomiting, and stomach pain.

Diarrhea can turn dangerous if it persists, as it can lead to serious dehydration. This can contribute to problems like confusion or fainting. If you have diarrhea, try to stay hydrated by drinking small, frequent sips of water or electrolyte sports drinks. Doing so can help you replenish the fluids and electrolytes that your body has lost.

If you develop diarrhea that’s intense or lingers on, let your healthcare provider know. They might want to check to see how you’re doing and let you know if you need more medical attention.

When should I contact a healthcare provider about Aduhelm side effects?

You should contact your healthcare provider as soon as you can if you experience any side effects from Aduhelm. Because many of the possible side effects are related to ARIA, your provider might want to perform brain scans to monitor for it.

If you have ARIA, there’s a good chance your healthcare provider will want to make a change to your treatment plan. During clinical trials, researchers stopped giving Aduhelm to anyone that had ARIA with noticeable symptoms. Some people were able to restart Aduhelm again after their ARIA went away.

If you don’t have ARIA, but your symptoms are still bothersome, your healthcare provider can offer management tips on how to get your symptoms under control.

Why trust our experts?

Written by:

Connie Zheng, PharmD

Connie Zheng, PharmD, is a drug information pharmacist at GoodRx and a licensed pharmacist in California. She has over 6 years of experience working in independent pharmacies.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Our editorial standards

Meet our experts