Why Did I Get MS?

by Lara DeSanto Health Writer

So you just received a diagnosis of multiple sclerosis (MS). If you’re like most people, right now you’re wondering, “Why me?” Is there a reason you got this chronic neurological disorder? Did you do something to cause your MS? Could you have prevented it? Let’s stop that negative spiral right now: It’s not your fault you have multiple sclerosis. Period. Understanding the roots of the disease and factors that raise your risk will help you see it’s not something you can control or plan for. This is what the experts have to say.

question marks

There’s No Single Known Cause of MS

Here’s the frustrating truth: We simply don’t know much about what causes MS, says Jacqueline F. Rosenthal, M.D, a neurologist at the Andrew C. Carlos Multiple Sclerosis Institute in Atlanta, GA. “There have been a lot of different things associated with MS, but nothing that’s been a clear causative factor—and that’s the frustrating part for patients,” she says. But while the cause remains a mystery, researchers do know specific factors that are linked to a higher MS risk.

perfect storm

It’s a Combination Effect

Developing MS likely involves not just one, but a combination of risk factors, says neurologist Lauren Krupp, M.D., director of the Multiple Sclerosis Comprehensive Care Center at NYU Langone Health in New York City. “These factors can be grouped into two big categories: Genetic and environmental,” she says. The way the factors play off each other can increase a person’s odds of developing this autoimmune condition. Let’s take a closer look at these individual factors.


Risk Factor: Your Genes

There’s an undeniable link between genetics and MS risk, says Dr. Krupp. Studies have identified 200 genetic variations in people with the disease. “For example, if an identical twin has MS, the likelihood of the other identical twin sibling having MS is 25 percent,” she says. Since the odds aren’t 100% though, it means more than genes is involved. “Having one of these genetic variations by itself usually isn’t enough—it’s being born with that variation, then being exposed to other environmental risk factors,” says Dr. Rosenthal.

Epstein-Barr virus

Risk Factor: Certain Infections

Weird but true, if you had the Epstein-Barr virus (EBV)—which causes mononucleosis—you could be more susceptible to developing MS. This isn’t to say mono causes MS, “but MS is more common among people who have had infectious mono,” Dr. Krupp says. “And if you look at children who have MS, which is an uncommon group, they’re more likely to have evidence of exposure to EBV early compared with kids who don’t have MS.” Other viruses and bacteria may also raise your MS risk, for reasons not yet understood.

vitamin D

Risk Factor: Vitamin D Deficiency

Vitamin D deficiency is linked to many conditions, from depression to heart disease. The theory is that this vitamin plays a key role in keeping your immune system functioning properly. And now, researchers believe vitamin D (or lack thereof) plays a role in the development of MS, too. “At the time of diagnosis, most folks do have low vitamin D levels,” says Dr. Rosenthal. “And there is literature to suggest that if your vitamin D is in the higher range of normal, you’re at a lower risk of developing MS.”

overweight young woman

Risk Factor: Obesity

“Childhood obesity is another risk factor for MS,” Dr. Krupp says. Multiple studies have found that obesity in kids and teens, especially girls, increases the likelihood of getting MS in the future. For example, a large 2019 study in JAMA Neurology found that kids and teens who were overweight or obese were twice as likely to have MS than non-overweight children. Scientists are still trying to understand the correlation, given that not all people who are carrying extra pounds will develop MS.


Risk Factor: Smoking

It’s no secret that smoking has devastating effects on your health, raising your risk of lung cancer, heart disease, diabetes, and more, according to the Centers for Disease Control and Prevention. Not surprisingly, cigarette smoking also raises your odds of getting MS, says Dr. Rosenthal. Smoking is linked to having more severe MS and faster progression of the disease, says the National MS Society—so if you’ve been diagnosed with MS and you’re a smoker, quitting is really important.

world map

Risk Factor: Where You Live

Strange as it sounds, researchers have found that your MS risk rises depending on your location. “The biggest clue that environment has something to do with MS came from the observation that MS is more common in regions of the world that are farther from the equator, and less common near the equator,” Dr. Krupp says. It’s not 100% clear whether it’s tied to the geography itself or things like ethnicity, genetics, and infections that may be linked to those regions, according to the National Multiple Sclerosis Society.

artificial sweetener

Debunked Myths About MS Causes

While any of these factors may have played a role in raising your MS risk, there are plenty of things that aren’t risk factors but are still erroneously referenced in popular culture. For instance, MS is not related to environmental allergies, pets, artificial sweeteners, exposure to heavy metals, or your diet. “It’s not because of certain habits, or whether you ate or didn’t eat something,” says Dr. Krupp (who points out that diet can play a role in helping you manage MS symptoms).

the future

Remember: It’s Not Your Fault

The key here is understanding the distinction between correlation and causation. Just because there is a connection between these variables and MS doesn’t mean it’s a cause-and-effect one. “The important thing is to recognize that there’s nothing you did to get MS,” Dr. Krupp says. “You can’t blame yourself for this.” Rather than picking apart your past, try to look to the future with hope: With better MS treatments than ever before, you can learn to manage this condition.

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at WTOP.com.