MS Heat and Temperature Sensitivity

Why does heat affect my MS?

Multiple sclerosis (MS) can make people more sensitive to heat due to nerve damage in the central nervous system. This is called Uhthoff’s phenomenon, where an increase in body temperature can temporarily worsen MS symptoms.

When you have MS the protective myelin sheath around nerves is damaged, slowing down nerve signal transmission. Heat (from weather, exercise, hot baths, fevers, etc.) can further disrupt these signals, leading to a temporary worsening of symptoms.

Common MS Heat Intolerance Symptoms

• Fatigue – Feeling more drained than usual
• Blurred vision – Often called “heat-related optic neuritis”
• Weakness – Muscles may feel weaker or more uncoordinated
• Numbness & Tingling – Sensory symptoms may increase
• Cognitive Fog – Difficulty thinking clearly
• Balance & Mobility Issues – Increased trouble walking
• Bladder Problems – Urgency or difficulty emptying

The good news is that these effects are temporary – once the body cools down, symptoms usually return to baseline.

Certain activities can cause this heat sensitivity to become more apparent, such as taking hot baths or showers, sunbathing and exercising. In fact, in the days before lumbar puncture and MRI scans, MS was often diagnosed by placing a patient in a hot bath to see if it made their symptoms worse.

MS Heat Sensitivity explained by Dr Gretchen Hawley

Dr Gretchen Hawley explains heat intolerance isn’t just caused by the temperature outside. It’s anything that causes your core temperature to rise by at least 1 or 2 degrees – like a warm or hot shower, mental or emotional stress, exercise, doing chores, etc. She shares her best strategy is to understand what your triggers are (what causes your symptoms to worsen) and sip ice-cold water before, during, and after your trigger.

How to stay cool

Here are some great ways to stay cool and prevent heat-related MS symptoms:

1. Keep Your Environment Cool

• Use fans and air conditioning whenever possible.
• Keep curtains or blinds closed during hot days.
• Try a cool mist spray bottle or a damp cloth on your neck.

2. Stay Hydrated

• Drink plenty of cold water throughout the day.
• Avoid excessive caffeine and alcohol, as they can dehydrate you.

3. Wear Cooling Gear

• Cooling vests, scarves, and wristbands can help regulate body temperature.
• Wear light, breathable, loose-fitting clothes (cotton or moisture-wicking fabrics).
• A hat with a brim helps shade your face from the sun.

4. Be Strategic About Activity

• Exercise in the morning or evening when it’s cooler.
• Choose water-based workouts (swimming, water aerobics).
• Take frequent breaks in the shade or air conditioning.

5. Cool Down Quickly

• Take cool showers or baths.
• Soak your feet in cold water to bring your body temperature down.
• Eat cold snacks (frozen fruit, popsicles, chilled smoothies).

6. Plan Ahead

• Check the weather forecast before going out.
• If possible, schedule activities indoors or in shaded areas.
• Let others know about your heat sensitivity, so they can support you.

Keeping your core temperature neutral

Dr Gretchen shares her top tips on how to keep your core temperature neutral. If your MS symptoms are flaring lately, it could be due to the change in temperature! Any time the temperature changes, one or multiple symptoms can temporarily flare or worsen. Dr Gretchen shares her top tips on managing your core temperature in different climates.

Managing sweating at night

Night sweats are severe hot flushes occurring at night that can drench sleepwear and sheets, which are not related to the environment. 

Some cases of night sweats are caused by types of medications you may be taking. Speak to your doctor if you feel like this is affecting you.  

There is no ‘cure’ for night sweats, but there are several things you can do or implement to help yourself feel cooler.

• Climate control mattress toppers are available and have reportedly helped the community have a more comfortable sleep and not experience such severe night sweats. 
• Keep blinds or curtains closed during the day in your bedroom, so the room is cooler when it comes to bedtime.
• Avoid sugar, caffeine, alcohol and spicy foods before bed. 
• Make sure you drink plenty of water during the day to stay hydrated. 
• Wear loose garments in bed.  

Follow this link to discover more tips on managing sweating at night for your MS.