Myelin melting from the heat and dripping into a puddle.

For Our Family & Friends: MS, Heat & Humidity

When I think about my life with Multiple Sclerosis, I often consider how much easier my life would be if there was a greater breadth of knowledge about the disease amongst everyone around me. If people knew a bit more about the disease, life would be better, not only for myself, but for my friends, family, and coworkers as well. A little bit of knowledge can go a long way. With that in mind, I’ve endeavored to create a few articles with some basic information about the disease and how it affects us. My hope being that these can be shared with our family and friends to allow them to better understand what’s going on with us. As I’m writing this first one in the middle of a crushing summer heatwave, I’ve decided to focus this first piece on the effects of temperature and MS.

MS basics

Heat and high humidity can cause a temporary worsening of our symptoms. With MS, the disease causes our own immune system to attack a substance called myelin surrounding our nerves. Myelin acts as insulation for the nerves throughout our body. This insulation helps the electric signals our brain is sending throughout our body to travel at a steady speed. As our immune system eats away at this lining, we begin to have problems with the signals our brain sends. They no longer get where they are going in a fast enough time (or even at all).1,2

Our nerves are the way our brain communicates with the rest of our body, so there are many possible ways this kind of damage can affect us. Example: our brain tells our foot to lift when walking, but if the myelin on the nerves that connect the brain and foot are damaged, that signal may not get there in time. So instead of lifting my foot, it stays in place or doesn’t lift high enough, even though the rest of my body is still performing all the actions needed to walk. This ends up with me falling. If the conditions are right, that signal may still make it on time, despite the damage (it’s like a frayed phone charging cable, it may still charge your phone if it’s in the right position, but move it slightly and it won’t work).2

Temperature, humidity, and heat intolerance

This is how temperature and humidity come into play. They can worsen the conditions for that signal to get where it’s going because of that damaged nerve.1

While this is a huge problem on hot and humid days, the reality is, it doesn’t take that big of a change for this to be an issue. Even the slightest increase in body temperature can be enough to start causing problems. By slightest, I mean as low as one-quarter to one-half a degree increase in body temperature.1

Think about some of the times your friend or family member with MS started to have issues, maybe they didn’t fall, but they acted differently, or suddenly had to leave somewhere or cancel plans. Was it a hot day? Was it wintertime, but in an overly heated room? Was it as a gathering that had a lot of people (groups of people close to each other produce heat, parties tend to get warm after a while)? After a few decades with the disease, I can usually tell when my body temperature raises a half-degree or so, then I know I need to cool off, but not everyone is able to notice that difference, especially early in the disease.

It’s temporary

The good thing about this issue is that it’s temporary. Typically, if we can get our body temps cool again, we will return to normal. However, it doesn’t always happen that quickly. Even if it does, it can be a pretty trying and exhausting experience, one that may require us to rest.1

Cold can affect MS, too

While hot temperatures and humidity are often the most talked-about conditions, for some people with MS, the cold can also cause problems.1 Another important thing to note here, you can still have high humidity even when it’s cold. Some of my worst days have been when the outdoor temps would be considered perfect for some, but the high humidity left me a wreck.

It’s awful

Finally, I want you to know how awful this can be for so many people with MS. While it may seem trivial to most, an increase in heat and humidity can be devastating to someone with Multiple Sclerosis. It can cause every issue we’ve ever had with MS to suddenly come to the forefront. Blurred vision, burning nerve pain, confusion, numb/weak limbs, intense spasms. I can honestly say, there have been times when I’ve been too hot and wanted to kill myself because of the way it made me feel. That’s not a trivial thing to say. Prolonged time in the heat can cause some severe issues as well. So severe, that there are reports of it killing people. You simply can not underestimate the danger of temperature and humidity changes for those with MS.

I hope I’ve helped illuminate how increases in heat and humidity can affect those with Multiple Sclerosis. Please consider this information when dealing with your loved ones. They aren’t just hot, they are having legitimate issues that should be taken seriously.

Thanks so much for reading and as always, feel free to share!


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Editor’s note: Temperature and heat in the summer can take a physical and emotional toll on those with MS. If you or someone you know is struggling, please know that there are many resources available for support including the National Suicide Prevention Lifeline (1-800-273-8255) and online chat, and the MSAA toll-free helpline (800-532-7667, extension 154) and online chat.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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