MS patients are especially vulnerable to high heat, but there are several products on the market to help them keep cool this summer.

Before MRIs and lumbar punctures to diagnose multiple sclerosis (MS), patients suspected of having the disease were often subjected to the Hot Bath test. If they experienced an increase in weakness or fatigue or any loss of vision when submerged in a vat of hot water, they were diagnosed with MS.

In the early 20th century, Wilhelm Uhthoff was the first to recognize the link between heat and MS, but because he was an ophthalmologist, his observations focused primarily on visual symptoms. The temporary, heat-induced increase in MS symptoms, whether brought on by a fever, exercise, or the climate, is now referred to as Uhthoff’s Syndrome.

In a study published in 2011, Swedish researchers found that more than 70 percent of all MS patients experience some degree of heat sensitivity.

According to the study authors, “The most striking result in this study is that heat sensitivity is significantly correlated with—and…appeared as an explaining factor for—the most incapacitating symptoms of MS: fatigue, concentration problems, and pain. This result discloses heat sensitivity as a key clinical factor.”

With summer close at hand, it’s important for MS sufferers to take precautions to prevent unnecessary exposure to heat, or to compensate for unavoidable exposure.

Simple lifestyle changes, such as gardening at sunrise or sunset rather than during the heat of midday, can make all the difference in managing MS symptoms. And make sure you always have shade available, even if it means carrying an umbrella everywhere you go.

“Heat sensitivity is one of the most commonly seen symptoms in MS,” says Scott Silliman, M.D., Director of the Comprehensive MS Program at the University of Florida, “I’d say roughly 50 to 60 percent of my patients experience it. I usually see [heat sensitivity] most in people with spinal cord MS and in those with optic neuritis.”

But, Silliman adds, “It’s not dangerous and doesn’t alter the course of their MS. Exercise-induced heat sensitivity is seen more with weight training and less with aerobic type workouts. Keeping your head and neck area cool with one of the many products on the market can help.”

Anne P., who asked to remain anonymous, has been living with relapsing-remitting MS in the Georgia heat since 1998. She knows the dangers of heat exposure all too well.

“Every part of my body that has ever been impacted during an exacerbation starts to fall apart,” Anne said. “My vision gets fuzzy, my speech begins to slur, my fingers get tingly, and my gait gets thrown off. It’s not pretty! I schedule any errands or appointments in the morning hours in order to ensure I am home and in the A/C no later than 2 p.m.”

In southern states especially, finding ways to overcome heat intolerance is a priority.

“We know from living in North Florida that many people with MS experience a temporary worsening of their symptoms when the weather is very hot or humid or when they run a fever, sunbathe, get overheated from exercise, or take very hot showers or baths”, said Corrina Steiger, President of the North Florida Chapter of the MS Society. “The National MS Society has many programs to help people with MS affected by the heat, such as providing cooling vests or assisting with increased electricity bills due to air conditioner usage.”

And for those who cannot–or choose not to–avoid the great outdoors, there are many products on the market that can cool you down when the mercury rises, from simple fan-topped spray bottles available at most drug stores to complex cooling vests designed specifically for MS patients.

One of the more versatile cooling devices on the market is the Chilly Pad, a $15 to $20 scarf-shaped piece of fabric that, once dampened, displays unique cooling properties. It can be draped around your neck, wrapped around your head or wrists, or laid across your legs to offer maximum cooling on the hottest parts of your body.

Another creative approach to addressing hot weather symptoms, for women in particular, is TaTa Coolerz, developed by businesswoman Kim Gillespie. These cooling pads are, as you’d expect, worn concealed inside the bra.

“We began working on the prototype in 2009 for a cooling device that could be discreetly worn by women to help cool core body temperatures,” Gillespie said. “Hopefully, once the patent is approved, we will have the funding to create a whole line of products.”

So, do what you can to beat the heat this summer season. “Nerve transmission requires more energy to work in the heat, and even more when there is demyelination, leaving the person with MS feeling wiped out!” said Megan Weigel, a nurse practitioner at Baptist Neurology in Jacksonville, Fla. “It is extremely important to consider using cooling equipment once the temperature starts to rise and during exercise. It is also important to stay well-hydrated. Hand-held fans, small ice packs, cold water bottles, neck wraps, and cooling vests are great things to keep on hand as summer approaches.”

If you or a loved one has MS, have a plan in place for staying cool, but also be ready for the unexpected. For example, a car break-down could leave you stranded with no way to cool down. A battery-powered spray bottle fan filled with water and tossed in the trunk might be all you need to keep Uhthoff’s Syndrome at bay.