For many people living with multiple sclerosis (MS), heat is more than just an uncomfortable weather condition. It can worsen symptoms and impact daily life.

Community members on MultipleSclerosis.net share their experiences when it comes to dealing with the heat. Here is what they wish people knew about how heat affects their MS. Read on for their insights.

How heat impacts MS symptoms

This sensitivity to heat – often referred to as Uhthoff’s phenomenon – occurs because the nerve fibers in people with MS have lost some of their myelin, the protective coating that helps nerve signals transmit efficiently. Increased body temperature can further impair this transmission.

As a result, people with MS may experience a temporary worsening of their symptoms, such as:

• Fatigue
• Weakness
• Vision changes
• Balance problems
• Numbness in the arms and legs
• Cognitive difficulties 
• Slowed reaction times

These symptoms vary from person to person. Symptoms should improve once you cool down.

The role of humidity

Humidity plays a significant role in MS symptoms. The combination of heat and humidity is particularly challenging, as these community members will attest:

“When I feel warm and damp at the same time, I fall into a sluggish fog, and everything slows down, including my movements and my speech. This feeling almost always precedes an MS hug. I might also face the onset of a migraine, digestive issues, and overwhelming fatigue.” 

“Humidity is my top symptom. I hibernate in the summer while others head to the beach (a mile away). I cannot wear any knits. Quick dry t-shirts only. I can almost tell the humidity level before I open my eyes in the morning. It lets me know what kind of day I’ll have.”

“Felt worse for years in the humid summer in the northeast, and I rarely go out in the hot summer sun. Heat intolerance is at a minimum when you DON’T sweat, no matter how much you drink. Not sure a hotter climate, humidity or not, would help the situation though.”

Dew point makes a difference

Dew point, which is a more accurate measure of the actual moisture content in the air, can be a more reliable indicator of how heat and humidity will affect someone with MS than relative humidity alone.

“Dew point temperatures are what I resonate with! Dew points of 60° and above are rough. If 65° and above, I’m basically homebound, and my MS symptoms flare. It’s rough being a ‘human barometer,’ right!? I cannot count on a humidity temp to tell me how I will feel…The dew point is way more predictable. I really wish the weather forecast would swap humidity with dew points.” 

“I like to watch the dew point, which is the temperature at which dew is formed on surfaces. A dew point above 60° is considered borderline uncomfortable for most people, but I like it even lower. A dew point above 70° is tropical. When the toilet tank is wet, you know the dew point is high. I tell my family, ‘it’s so hot even the toilet is sweating!’”

Strategies for managing the heat 

Since the heat can be problematic for people with MS, many community members have tried and true ways they can cool down fast. Here is some practical advice for staying cool:

“I carry frozen bottles of water because I find if I have cold ice bags on my neck or low back I cool down fast. Being in a cool, dark, quiet place helps too.”

“I always keep at least 1 bottle of water in the freezer. Whenever I leave the house during warm weather, I pack my soft 6-pack cooler with water bottles and my frozen bottle. I keep frozen damp kitchen towels in baggies in there too.”

“I’ll actually put ice packs in my pockets when I go out to help keep cool.”

“I did come across an inexpensive ‘heat helper.’ It is a dog cooling pad. I have a few in different sizes…one I can even wrap around my shoulders and would help in a hot car scenario. You can get them online at any store that sells pet supplies. Doesn’t need batteries or charging. They work when pressure is applied, like laying or wrapping. Approved by this MSer and my pup!”

The emotional and social impact

Beyond the physical challenges, there is an emotional and social toll of heat sensitivity in MS. 

“These problems we have with temperatures can be very isolating. I’m at a point where I normally need to be in a nice air-conditioned room when it’s hot, or even slightly warm, out. That can be rough when it’s summertime and everyone wants to hit the beach or BBQ outdoors. If we aren’t around as much during warm weather, it’s not because of you, it’s because of our disease.”

“While the warmer months are normally most people’s most pleasurable times, they can be hell if you have MS. Not only do we physically feel awful because of the heat, but we also have to deal with feelings of missing out and of isolation. I know in my case, feelings of loneliness are a big problem, as most of my friends are out enjoying the weather, which would make me unable to even stand. Because of this, warm temps signify more than physical issues to me: They have an emotional and mental toll as well.” 

Coping strategies for the warmer months (beyond physical cooling)

Recognizing the emotional impact is crucial. Community members shared their ways of coping with the limitations imposed by heat: 

Building a supportive network to help combat feelings of isolation

“I find that the warmer months are some of the best times to reach out to others with MS who are also stuck in the same situation.” 

Engaging in indoor hobbies

“I also try to lean into my hobbies a bit more.” 

Managing social media

“My best advice for dealing with warmer months? Avoid social media as much as possible. There’s no need to throw another log on the FOMO (fear of missing out) fire!” 

References:
1. Heat Sensitivity. Multiple Sclerosis Association of America. Available at Heat Sensitivity | MSAA. Accessed 4/14/2025.