Many people with multiple sclerosis (MS) are sensitive to heat and changes in body temperature. For a person with MS, even a quarter- or half-degree change in core body temperature can temporarily trigger symptoms. Environments that others might not think twice about — a humid backyard, stuffy room, or hot shower — can make MS symptoms worse. This condition is called Uhthoff’s phenomenon.
The connection between heat and MS symptom flare-ups is so well-established that before the invention of MRI, doctors used to submerge people they believed to have MS in hot baths. If the person’s neurological symptoms suddenly flared, the physician would presume their diagnosis was correct.
Thankfully, tests like those are unnecessary today. What’s more, people with MS can avoid the complications and risks of heat sensitivity. It just requires some planning and preparation.
In people with MS, the body’s defenders (white blood cells) attack the central nervous system, causing inflammation and stripping the nerves of their protective coating (myelin). This process, known as demyelination, leaves the nerves vulnerable and reduces their ability to transmit electrical signals to the brain.
Research indicates that when a person with MS experiences an uptick in core temperature, neural conduction (the passing of messages along nerve fibers) slows down or, in some cases, is blocked entirely. The severity of the symptom flare-up depends on the extent of a person’s demyelination and how drastically their core temperature has changed.
Multiple sclerosis can negatively affect a person’s ability to maintain a healthy body temperature. If a person develops a lesion in an area of the brain that regulates core temperature or cooling responses (such as sweating or circulation), they may not be able to adjust to a warmer environment.
Heat intolerance, or heightened sensitivity to heat, is very common among people with MS. This condition affects between 60 percent and 80 percent of people with MS. These individuals may experience a pseudo-exacerbation (temporary symptom flare) if their core body temperature rises. Warm environments can trigger a temporary worsening of symptoms, as can exercise and fevers caused by illness or infection. Heat-triggered symptoms are temporary and typically fade once a person’s temperature returns to normal.
Watch MS expert Dr. Aaron Boster discuss how temperature changes can impact MS symptoms.
The MS symptoms most commonly associated with heat pseudo-exacerbations include fatigue, pain, concentration difficulties, and an increased need to urinate. One MyMSTeam member shared that they experience worsened muscle symptoms in the heat. During heat waves, they wrote, “The good old legs decide to fight me big time.”
People with MS may experience additional symptoms if their temperature rises under specific conditions. For example, Uhthoff’s phenomenon often occurs after a person’s body temperature rises due to exercise (or physical restraint, such as by a wheelchair tray or seat belt).
Relapsing symptoms or flares caused by heat can also create secondary health risks. As one team of researchers explained, heat sensitivity in people with MS is strongly correlated with fatigue. When compounded with cognitive problems and muscle weakness, fatigue and heat sensitivity have been reported as predictors of accidental falls.
When you’re in the middle of a heat-prompted MS flare-up, you can take a few immediate actions to cool yourself down, including:
If you opt for a cooling shower or bath, be sure not to shock your system with water that is too cold. Start with lukewarm water, then slowly lower the temperature.
You can reduce your future risk of pseudo-exacerbations by creating a schedule and home environment that takes temperature into consideration. Putting some time and resources into building a comfortable routine and home environment could help you avoid preventable heat flares and drastically increase your quality of life. As always, ask your doctor or neurologist what they advise for protecting yourself from the heat.
If you want to work out, you may want to do so in a cool environment. Avoid hot or stuffy rooms and, if you plan to exercise outdoors, try to do so during the cooler early hours or in the evening.
Don’t overexert yourself, and take regular breaks. As one MyMSTeam member shared, “My PT noticed one day that I don’t rest between activities. I just push on through. We had a serious talk about giving myself permission to rest.”
Be sure to have water on hand while exercising. Consider setting aside 30 minutes after your workout for a cooling bath or shower. This can help you safely lower your core temperature and keep cool.
If you live in a hot or humid climate, you may want to consider investing in air conditioning or fans. These will help you regulate the ambient temperature of your home and limit your chance of experiencing environmental heat triggers.
If you find that lightweight garments aren’t enough to help you cope with the heat, you may want to consider trying specialized cooling clothes. These garments are often specifically made for people who have MS. They contain a gel-like substance that can be chilled before use and provide cooling effects for several hours or days. Cooling garments come in a variety of forms, including neck wraps, bandanas, hats, and wristbands.
If you need more cooling support than gel-lined clothing can provide, you may want to try a cooling vest. These vests resemble waistcoats and feature battery-powered cooling packs that keep your torso cool. Because cooling vests are often designed for athletes, they usually stay comfortable even during vigorous physical activity. Research indicates that people with MS who use cooling vests are often able to walk farther and longer without fatigue than their peers.
Living with multiple sclerosis can be complicated and stressful — but you don’t need to face the challenge alone. MyMSTeam is the social platform designed to connect, support, and empower people who have MS.
On MyMSTeam, more than 187,000 members come together to share stories of life with MS. You can ask questions, provide insights, and even just make conversation with people who truly understand what it’s like to live with MS.
Have a tip to share on avoiding heat-prompted relapses? Start the conversation by leaving a comment below or making a post on MyMSTeam.