How Heat Affects Your Multiple Sclerosis— and What You Can Do to Stay Comfortable

You may notice your multiple sclerosis symptoms feel stronger on hot or humid days — and you’re not imagining it. When your body temperature rises, the nerve pathways affected by MS can temporarily slow down, making familiar symptoms feel more intense. The good news: these changes are temporary, not a flare, and usually improve once you cool down.  

At Elliot Health System, our MS care team, led by Ann Cabot, DO, is here to help you understand your heat sensitivity and find practical ways to stay safe and comfortable all summer long. 

Why Heat Can Make MS Symptoms Feel Worse  

MS can damage the protective coating around your nerves, making it harder for signals to travel smoothly. When your body warms up — from weather, exercise, or even a hot shower — those signals may slow down even more. This temporary change is known as Uhthoff’s phenomenon. 

According to the National Multiple Sclerosis Society, about 60–80% of people with MS experience heat sensitivity, making it one of the most common symptom triggers. 

What you may notice: 

• Fatigue that comes on quickly 
• Blurred or dimmed vision 
• Heaviness or weakness in your arms or legs 
• Tingling or numbness 
• Feeling off-balance 
• Cognitive “fog” or slowed thinking 

These symptoms usually fade once your body temperature returns to normal. They do not indicate new inflammation or disease progression. 

Common Triggers That Can Raise Your Body Temperature 

Everyone’s triggers are different, but many people find symptoms worsen with: 

• Hot, humid weather 
• Physical activity 
• Hot showers or baths 
• Fever or illness 
• Stress or overexertion 

Understanding your personal triggers can help you plan your day and stay ahead of symptoms. 

Practical Ways to Stay Cool and Comfortable 

Hydrate throughout the day 

Staying hydrated helps your body regulate temperature. Keep water nearby and choose hydrating foods like watermelon, berries, and cucumbers. 

Plan outdoor time wisely 

Try running errands or taking walks in the early morning or evening when temperatures are lower. On very hot days, choose shaded areas or indoor alternatives. 

Use cooling gear 

Many people with MS find relief with tools such as:  

• Cooling vests 
• Neck wraps 
• Wrist or ankle coolers 
• Portable fans 

These tools can make outdoor activities more manageable and help you stay active. 

Keep your home environment cool 

Use fans or air conditioning when possible. Close blinds during peak sun hours and take cool showers or baths to quickly lower your body temperature. 

Modify your exercise routine 

Movement is important for strength, mood, and mobility — but summer heat may require adjustments. Try: 

• Indoor pools 
• Air‑conditioned gyms 
• Shorter, more frequent sessions 
• Gentle stretching or yoga 

If symptoms increase, pause and cool down before continuing. 

Listen to your body 

Your heat sensitivity is unique to you. If you start to feel fatigued, heavy, or notice blurred vision, take a break before symptoms build. 

When to Call Your Neurologist  

Temporary heat related symptoms typically improve once you cool down. Reach out to your doctor or care team if:  

• Symptoms last longer than 24 hours 
• You notice new or significantly worsening symptoms 
• You’re unsure whether symptoms are heat‑related or a true flare 

Your care team can help you determine what’s normal for you and when additional evaluation is needed. 

You’re Not Alone — We’re Here to Help 

Heat sensitivity can be challenging, but with the right strategies, you can stay active, comfortable, and confident all summer long. Elliot Health System's MS care team provides comprehensive evaluation, treatment, and ongoing support for individuals living with MS. 

Learn how our MS team can support you at ElliotHospital.org/MS.