A man sneezing into his elbow while holding a popsicle

The Connection Between MS and Allergies

There are many things that experts do not understand about multiple sclerosis (MS). For example, they do not know what causes MS. However, research shows there may be a link between MS and allergies.1,2

This link is not yet proven, but researchers are studying the possible connection. They are also trying to learn what this connection could mean for MS treatments.1,2

Is there a link between MS and allergies?

MS is an autoimmune disease. This means that a person's immune system overreacts and attacks certain healthy cells in the body. In MS, the immune system attacks the protective cover on nerve fibers. This cover is called myelin.2

Allergies are also caused by an immune system response. In allergies, the immune system overreacts to an allergen like pollen or pet dander.2

These immune reactions make MS and allergies seem similar. But the specific immune responses that happen in MS and allergies are different. With allergies, the immune system produces histamine. Histamine is involved with the inflammatory response that causes allergy symptoms.3

Histamine may also be involved in the inflammatory response that occurs in MS and other autoimmune conditions. But researchers do not know if there is a definite link between histamine production and MS. There is still no proven link between MS and allergies. But there is a lot of research that points to a possible connection.3

Research on MS and allergies

A 2019 study focused on the links between different types of allergies and MS. It followed people over 10 years. Researchers looked at information like periods of increased symptoms (relapses) and damage shown on MRI scans. This study found a link between MS and food allergies.4

In the study, people with food allergies were more likely to have relapses and MS activity on MRI scans. This does not mean that other types of allergies are related to MS. It also does not confirm the link between MS and food allergies.4

Another study looked at the relationship between allergies and MS in children. This study found that having allergies did not increase a child's risk of developing MS. But researchers found that the children who had both MS and food allergies were less likely to have MS relapses.2

This study grouped food allergies and food sensitivities together. A food sensitivity means that a person's body cannot easily break down a certain food. So, eating the food may lead to digestive upset. But the exact reaction caused by a sensitivity is different from the reaction caused by a food allergy. So, this study cannot be directly compared to other studies that looked only at true food allergies.2

More research is needed to study the link between MS and allergies. This is especially true because different studies are reporting different results.2,4

What could this link mean for people with MS?

It is possible that the link between allergies and MS could mean more treatment options for people with MS. A small clinical trial in 2017 focused on using an antihistamine drug called clemastine fumarate on people with MS. The trial found that this drug may increase eye performance. Some people also had improvements in myelin growth (remyelination).1

The trial measured visual evoked potential (VEP). VEP is the time it takes a signal to get from the eyes to the brain. If this time is slow, it may mean there are problems with the visual pathway. In people with MS, this pathway can be damaged. The damage causes vision problems. In the trial, some people who took the antihistamine had improved vision.1

This could mean that antihistamines might help people with MS. But more research is needed to confirm this finding. It would take many more studies like this before doctors could begin to prescribe antihistamines to treat MS.1

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