A new study out of UC San Francisco has found that a widely available allergy medication may do more than just stop sniffles—it might actually help repair nerve damage caused by multiple sclerosis (MS).
Researchers discovered that clemastine, an over-the-counter antihistamine, helped restore the protective myelin sheath that covers nerve fibers—something that’s severely damaged in people with MS. This breakthrough could offer a new way to treat the disease, focusing on actual nerve repair rather than just managing the immune system’s attack.
What Happens in MS?
Multiple sclerosis is an autoimmune disease where the body’s immune system mistakenly attacks the myelin sheath, a protective layer around nerves. When this layer breaks down—a process called demyelination—nerve signals get disrupted. That leads to symptoms like numbness, muscle weakness, vision problems, and even paralysis.
Current treatments mostly aim to calm the immune system, not fix the damage. That’s where clemastine comes in.
The Study
The study involved 50 people with MS, who were part of the ReBUILD trial. Researchers split them into two groups:
- One group took clemastine during the first three months.
- The other started on a placebo, then switched to clemastine later in the trial.
To track whether the drug was working, researchers used a brain imaging technique called MRI to measure something called the myelin water fraction (MWF). This measures the amount of water trapped in layers of myelin—a good sign of how healthy and intact that myelin is.
The results were encouraging. In both groups, myelin levels increased after they began taking clemastine. Even more exciting, this improvement was seen not just in visibly damaged brain areas, but also in regions that looked normal on scans—suggesting that the drug may help repair hidden damage, too.
A New Way to Track Myelin Repair
Researchers now believe MWF should be the new standard way to track how well potential treatments repair myelin in the brain. This could help speed up testing for future drugs aimed at restoring nerve function.
“This is the first example of brain repair being documented on MRI for a chronic neurological condition,” said Dr. Ari Green, the study’s senior author. “It’s real biological evidence that remyelination is possible.”
So, Should You Take Clemastine?
Not so fast. While the results are promising, clemastine is only partially effective at doses that are safe to take. One downside: it can make you sleepy—a problem for people already dealing with fatigue from MS.
Still, the findings are a big step forward. Clemastine won’t cure MS, but it may be the first real proof that we can reverse some of the damage it causes. Researchers are now looking into using the drug to help premature babies who suffer from similar types of brain injury.
The study was published in PNAS (Proceedings of the National Academy of Sciences).
Source:
https://www.pnas.org/doi/10.1073/pnas.2217635120
https://clinicaltrials.gov/study/NCT02040298
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