Why heat makes myasthenia gravis worse and what you can do

Last updated July 30, 2025, by Susie Strachan
Fact-checked by Inês Martins, PhD

When you live with myasthenia gravis (MG), staying cool isn’t just about comfort; it’s an important part of managing your health. Heat can intensify MG symptoms, and even a slight rise in body temperature may trigger muscle weakness or fatigue that’s difficult to ignore.

That’s why it’s helpful to understand how heat affects your body and what you can do to stay safe. By using cooling techniques, tracking your symptoms, and adjusting your routine, you can take steps to stay safer and more comfortable on hot days.

How heat can affect MG symptoms

Heat sensitivity can show up in different ways. You may notice that your symptoms worsen during hot weather, after a warm shower or bath, or when you have a fever.

This happens because, as your body temperature rises, nerve signals have a harder time reaching your muscles, making everyday tasks, like walking, talking, or lifting things, feel more difficult than usual.

Humidity can make things even more uncomfortable. When the air is humid, your body can’t cool itself as efficiently through sweat. Even moderate temperatures can feel hotter, and your core body temperature may rise faster than you expect. The good news is that symptoms typically improve once your body cools down.

Cooling strategies to protect your health

If heat tends to make your symptoms worse, there are a few things you can try to help prevent or reduce flare-ups.

Stay indoors when it’s hottest

Try to stay indoors during the hottest part of the day, especially if it’s humid. Use fans or air conditioning when possible, and wear lightweight, loose-fitting clothing to help your body stay cool.

Also, consider keeping a wide-brimmed hat and a spare pair of sunglasses in your car or bag for when you’re out.

Try wearable cooling gear

Cooling scarves, vests, and neck wraps can help lower your body temperature, especially if you’re active or spending time outdoors. Some are even made with special materials that hold cold longer.

Cool down with a shower or bath

A cool shower or bath can help your muscles recover faster if you are overheated. Showering before and after exercise may also help regulate your body temperature.

Drink plenty of water

Dehydration can make it even harder for your body to cope with heat. Keep a water bottle nearby on hot days or if you’re moving around more than usual.

Pace yourself

Plan activities for early morning or evening when it’s cooler. Take breaks often and don’t push through fatigue. Rest is a key part in managing MG, especially in the heat.

Track symptom patterns to guide your care

Keeping track of when your MG symptoms worsen during hot or humid weather can reveal helpful patterns. Certain activities, such as exercising or spending time outdoors, may exacerbate fatigue, muscle weakness, or difficulty breathing or swallowing.

If you notice symptom changes, use a notebook, app, or printable tracker to record them so you can share these findings with your care team.

Sharing this information with your healthcare provider can guide discussions about possible adjustments to your daily routine, medication timing, or cooling strategies.

You might consider asking your provider questions such as:

• Could my medication schedule be adjusted for warmer months?
• What emergency steps should I follow if symptoms worsen in the heat?

Tracking these details can help your healthcare team better understand your day-to-day experience and plan care.

Know when to act on worsening symptoms

Discuss with your doctor the steps to take if your symptoms suddenly worsen in the heat.

It helps to keep an MG action plan and a list of emergency contacts in your wallet or phone. If you’ve been prescribed fast-acting medication for sudden weakness, keep it with you during hot weather or outdoor activities.

If you experience increased difficulty breathing, swallowing, or speaking, seek medical attention immediately. Heat-induced myasthenic crises are rare but serious and require emergency care.

Myasthenia Gravis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.