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6 Ways to Beat the Heat When You Have MS

By Lisa Marie Basile
Reviewed by Dana Cooper, M.D.
June 21, 2024

Have you ever felt like your body temperature is way warmer than everyone else’s? Or noticed your symptoms start to flare once summer hits? You’re not imagining it. People who have multiple sclerosis (MS) are often much more sensitive to heat than those who aren’t living with the condition.

In fact, MS heat sensitivity has a name: It’s known as Uhthoff's phenomenon, or Uhthoff's syndrome, and it occurs in 60%–80% of people with the condition.

While it’s not entirely clear how or why heat is an issue for those with MS, Lauren B. Krupp, M.D., board-certified neurologist and director of the Multiple Sclerosis Comprehensive Care Center at NYU Langone in New York City, offers an explanation: Heat sensitivity is likely due to the immune system wearing away the myelin, or protective covering, around the nerve cells within your brain and spinal cord. This is known as demyelination, a hallmark of MS. Without myelin, nerves are less protected, leaving you more likely to feel the heat—literally.

“Think of a wire with insulation,” Krupp says. “The insulation protects the wire from the elements. But in MS, the nerves become more exposed to the environment. So, if the environment leads to a higher core temperature, that nerve will feel the effects of that temperature in ways a myelinated nerve would not.”

Being warmer, even by one quarter of a degree, can lead to an exacerbation of MS symptoms, including (but not limited to) sensory disturbances, increased fatigue, a heavy feeling in your limbs, or blurry vision.

This might occur from “going in a sauna or hot water, or if the ambient temperature is just very warm,” says Barbara Giesser, M.D., board-certified neurologist and MS specialist at Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, California. Some people may even experience heat sensitivity after a hot meal or during exercise.

The good news? MS heat sensitivity itself doesn’t contribute to disease activity or damage, even if it spikes symptoms temporarily. And fortunately, the symptoms that were triggered by high temperatures tend to pass after you cool down, Giesser says.

How to Stay Cool on Warm Days When You Have MS

MS and heat don’t mix, but implementing these strategies may help you keep cool when the mercury rises.

1. Avoid Peak Sunlight

Avoid going outside during peak sunlight hours, which are between 10 a.m. and 2 p.m., suggests Krupp. In general, try to stay inside an air-conditioned home or office on very humid and hot days. Avoid sitting directly by the window or in a sunroom, and invest in shades or curtains to help keep direct sunlight out.

2. Wear Cooling Garments

Try wearing MS cooling garments to beat the heat, suggests Krupp—especially if you have to be outdoors or you’re working up a sweat during dance class or on a hike. Cooling packs can be worn in and under clothing, including sports bras or other workout gear. Cooling vests for MS are also available from retailers like ThermApparel or Polar Products. These may be particularly helpful if you’re working in a hot office or commuting in a stuffy train car or bus.

If you need help affording a cooling vest, you can apply to receive one through the Multiple Sclerosis Association of America's Cooling Distribution Program.

3. Exercise Smart

While working out, in addition to wearing cooling garments, try dressing in moisture-wicking activewear materials that won’t trap excess heat.

Position yourself in front of a fan while you’re moving, suggests Giesser, and avoid stuffy gym environments, saunas, or hot yoga classes.

If you opt for an outdoor workout, schedule it before or after peak sunlight hours. And if you like to swim, stick to an unheated pool with a water temperature below 85 degrees.

4. Cool Yourself with Icy Drinks

Stay hydrated and cool with icy drinks (like healthy granitas or slushies made with fruit and ice), ice pops, and ice chips. Avoid alcoholic beverages or drinks with excessive sugar, which can dehydrate you and have negative effects on MS symptoms.

5. Use a Fan

Place a fan pointing at you, wherever you spend most of your time. This might be on your office desk or in your living space.

That said, it’s also important to know when a fan just won’t cut it. Research suggests fans may not be helpful in extremely hot, dry weather—so use your judgment and opt for air conditioning when it seems appropriate.

6. Avoid Extreme Cold Temperatures

Although a cold plunge may seem tempting, research published in 2018 in the journal Temperature suggests that sitting directly in front of an air conditioner or jumping into a frigid bath may also exacerbate MS symptoms.

The bottom line: Keep cool, but don’t overdo it. “The goal should be to stay comfortable,” Giesser says.

Work with your doctor to discuss your MS heat sensitivity symptoms and find what works best for you to keep cool—especially during those balmy summer months.

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