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How to Beat the Heat

Lynda Hillman, DNP, ARNP 

If your MS symptoms are worse when it’s hot, you have plenty of company. Approximately 75% of people with MS have heat sensitivity. You may have heard heat sensitivity or heat intolerance referred to by its medical term, “Uhthoff's phenomenon.” Regardless of what name you use, heat intolerance is unpleasant and can interfere with your usual activities. Why does heat intolerance happen? And what can be done to stay more comfortable?

Hot temperatures affect nerve functioning by slowing or blocking transmission of nerve impulse conduction. Another way to look at it is that the electrical messages sent to and from your brain and the rest of your body are garbled or never arrive. Nerve conduction is already impaired due to axonal demyelination and degeneration from MS -- heat makes this far worse and symptoms flare up.

Hot weather, vigorous exercise, a hot bath, or a fever are just a few examples of circumstances where heat can exacerbate MS symptoms. A rise in your body’s core temperature by as little as 0.25°F can produce symptoms. Even if only skin and not body core temperature is increased – for example, with direct sunshine or being in a hot room – that may be enough to trigger worsening of your symptoms.

While fatigue is the most common reaction to heat, any symptom of MS may occur, including cognitive dulling, increased spasticity, weakness, or visual disturbances. In hot environments, people with MS may therefore also find it harder to balance when standing, walking, or transferring which can increase the risk for falling. Heat can also affect the nervous system’s ability to regulate internal temperature. This results in a decreased sweating response, so you have less evaporative cooling.

You’ll have an easier and safer time coping with the heat when you’re prepared. Let’s take a look at some ways to do that.

The best strategy is to avoid heat if possible.

  • Stay out of direct sun or wear wide-brimmed hats and use sun umbrellas.
  • Recreational swimming or pool therapy water should be less than 85°F.
  • Avoid saunas, hot tubs, and activities such as “hot” yoga.
  • Avoid exercising during hot weather, particularly the hotter parts of the day, or have a shorter workout.

It’s not always possible to avoid the heat. What about summer when you want to enjoy the backyard with your grandkids, or stay reasonably comfortable in places without air conditioning? Or, think of the MS Veterans competing in the annual National Veterans Wheelchair Games (NVWG). How are they able to perform during events such as cycling, wheelchair basketball, power lifting, archery, and obstacle-course racing? Practical cooling strategies can help and will work even better in lower-intensity situations.

  • Use wet wraps – top your head with a cloth hat soaked in cool water or drape an iced or cold wet towel over your shoulders. This is a frequently used technique at the NVWG, where they keep a constant supply of towels and buckets of icy water.
  • Pre-cool by wearing a cooling vest for 30 to 60 minutes prior to being active. Vests, neck wraps, and other garments which use ice packs to cool you are available in many different sizes and styles. Talk with your MS provider or therapist about which ones would work best for you.
  • Take frequent sips of cool drinks. A recent study found that people with MS doing vigorous exercise who drank about 9 ounces of 34°F water every 15 minutes increased the time they could exercise by about 30%. Smaller volumes of icy water should work well if you’re doing lighter exercise or are sedentary.
  • Minimize caffeine intake. Caffeine increases urination and causes risk of dehydration.
  • Take a cool shower before and after exposure to heat.
  • Wear loose, breathable clothing in light colors.
  • Keep a spray bottle filled with cold water nearby for refreshing spritzes.
  • Use fans and air conditioning in your home and vehicles. Talk with your MS provider about air conditioning units which may be covered under your VA benefits.

These cooling strategies are low-tech and simple yet can make a world of difference in helping you enjoy the upcoming warmer weather and longer days.