Key takeaways

  • Myasthenia gravis (MG) is caused by decreased acetylcholine activity in your body. Because caffeine slightly increases acetylcholine activity, there is some interest in how it may affect MG symptoms. But there’s no evidence that caffeine is helpful or recommended for managing MG symptoms.
  • If you have MG and want to consume caffeine, check with your neurologist first, consume caffeine in moderation, and watch carefully for side effects.
  • Caffeine may cause side effects such as urinary frequency and sleep disruption, but these can affect anyone — they are not specific to people who have MG.

Myasthenia gravis (MG) is an autoimmune disease that prevents the neurotransmitter (messenger chemical) acetylcholine from sending signals between your nerves and your muscles. When those signals are not transmitted properly, you may experience MG symptoms such as muscle weakness and difficulty with certain movements.

Treatment for MG focuses on increasing the availability of acetylcholine in your body. In theory, caffeine might help in this process, but caffeine can also cause some side effects.

Caffeine can have a range of effects, both positive and negative, in people with MG and in the broader population.

A slight increase in acetylcholine activity

Caffeine binds to adenosine receptors, causing changes in your body’s levels of some neurotransmitters, including acetylcholine. But caffeine only slightly increases acetylcholine activity, and it’s not clear whether that minimal change would have any impact on MG symptoms.

Anecdotally, some people with MG say they feel better after consuming caffeine, some say they feel worse, and many don’t feel a difference.

Research shows that caffeine can affect acetylcholine activity, but the impact is not significant enough to affect neurological diseases that are associated with decreased acetylcholine activity, such as MG and Alzheimer’s disease.

Possible worsening of a cholinergic crisis

When living with MG, you are at risk of experiencing a cholinergic crisis, a serious medical condition that can happen when there’s too much acetylcholine in your body. During a crisis, you might need a ventilator to help you breathe because your muscles are too weak for you to breathe on your own.

Cholinergic crisis is usually associated with high dose acetylcholinesterase (AChE) inhibitors, which are a common type of medication for MG. AChE inhibitors prevent the breakdown of acetylcholine.

There’s no evidence that caffeine consumption alone can bring on a cholinergic crisis, but it might worsen a crisis by further increasing acetylcholine levels.

Seek medical attention right away if you’re experiencing cholinergic crisis symptoms, such as:

  • sweating and diarrhea
  • frequent urination
  • constriction of your pupils
  • airway tightening and excessive mucus production
  • vomiting
  • eye watering
  • increased saliva production

Improved exercise performance

According to the International Society of Sports Nutrition, consuming caffeine before exercise might help improve muscular endurance and strength during workouts in the general population. But it’s not known whether caffeine affects exercise performance any differently in people with MG.

Common side effects

Caffeine can cause a variety of side effects in people both with and without MG, especially when consumed in excess. The Food and Drug Administration (FDA) generally recommends consuming no more than 400 milligrams of caffeine per day.

Coffee, tea, and other caffeinated beverages can trigger urinary urgency or incontinence (a loss of bladder control), especially in people who already have bladder sensitivity.

If you already experience urinary symptoms, caffeinated drinks can make them worse. And drinking fluids before bed — whether they’re caffeinated or not — may cause nocturia (nightime urination), which can disrupt your sleep.

It’s always best to avoid caffeine before bed because it can keep you up at night. In addition to drinks such as coffee, tea, and soda, caffeine is found in some foods, including chocolate, protein bars, and many other snacks. It’s a good idea to check food labels for caffeine and to avoid consuming those foods close to bedtime.

Other possible side effects of excessive caffeine consumption include:

  • headaches
  • dizziness
  • anxiety and restlessness
  • a rapid heart rate

If you have MG and want to consume caffeine, here are some ways you can do so while still supporting your health.

Check with your doctors

In addition to causing some side effects, caffeine can interact with certain medications. Talk with your neurologist and any other doctors you see to make sure caffeine consumption is safe in your specific medical situation.

You should also let your neurologist know if you notice any changes in your MG symptoms after consuming caffeine. They may advise you to adjust your caffeine intake depending on how it affects you.

Avoid hot drinks

Heat can be a trigger for MG and make your symptoms worse. Drinking hot coffee or tea can especially affect your mouth or throat. So, if you have MG and want a caffeinated beverage, it’s better to choose a cold one.

Consider trying caffeine before exercise

Physical activity might not reduce fatigue in MG, but there is some evidence that exercise can improve muscle strength and daily functioning. Taking caffeine about 1 hour before exercise might help improve your performance.

Try a small amount and take note of how it affects your exercise. You might feel more energy, faster movements, or improved strength — or, because caffeine is a diuretic, you might find that you need to pause your workouts to use the bathroom. It’s also possible that you’ll notice no change at all. You can adjust your caffeine intake depending on how it affects you.

Avoid consuming caffeine before bed

Caffeine is a stimulant that can interfere with sleep quality — and if you’re not getting enough sleep, your MG symptoms may be worse.

As part of good sleep hygiene, try not to consume caffeine in the afternoons or evenings. If caffeine is part of your daily routine, limit it to the morning hours.

Consume in moderation

Consider monitoring your caffeine intake to see how it affects aspects of your physical health such as urinary symptoms, muscle strength and endurance, and sleep quality. If you have trouble getting to sleep or experience increased bladder sensitivity, you might want to reduce your caffeine intake.

Caffeine can slightly increase the amount of acetylcholine in your body, but it’s not clear whether the drug has any beneficial effect on MG symptoms.

Consuming caffeine before exercise has the possible benefit of improving muscle strength and endurance, but that effect is not specific to people with MG.

Caffeine consumption can have some downsides, including possible bladder irritation and sleep disruption. Pay attention to how caffeine affects you, and consider adjusting your intake if you experience unwanted side effects.

Having too much acetylcholine in your body can cause a cholinergic crisis, a serious medical condition that can occur in people with MG and requires emergency medical attention. It’s important that you know the symptoms of a cholinergic crisis and seek medical attention right away if you experience them.