Myasthenia gravis (MG) prevents your muscles from working the way you expect them to, and the resulting muscle weakness can lead to fatigue. Many people with MG also experience chronic fatigue that can get in the way of normal daily activities and affect their quality of life.

If you’re experiencing muscle weakness and fatigue with MG, it’s important to understand what’s happening in your body. That way, you can have productive conversations with your health care team to find the best possible treatment options to manage all your symptoms.

Muscle Weakness Can Lead to Fatigue

With MG, your immune system makes abnormal antibodies (immune proteins). These antibodies attack neuromuscular junctions (where your nervous system contacts your muscles). Many different areas of your body can lose muscle strength, including your eye muscles, eyelid muscles, face and throat muscles, and (in generalized myasthenia gravis) arm and leg muscles. When it’s severe, the neurological disorder can also affect the muscles you use to breathe, which can cause breathing problems and issues with your airways.

Muscle fatigue is different from muscle weakness. Fatigued muscles feel tired but not necessarily weak. Muscle fatigue may be associated with muscle use, but it can also occur on its own. People with MG can experience fatigue in different ways.

Early Fatigue

In some people who live with myasthenia gravis, muscle fatigue is related to muscle use. This type of fatigue is called “early fatigue.” In early fatigue, muscle fatigue gets worse as the muscle gets more exercise. Using your muscles for physical activity — even just using your eye muscles to keep your eyes open and blink — may lead to more intense feelings of muscle fatigue.

Chronic Fatigue With MG

Normal fatigue is temporary and may result from lack of sleep or a hard day’s work. Chronic fatigue is long-lasting, and it is not caused by working too hard. In one study, more than half of participants diagnosed with myasthenia gravis reported symptoms of chronic fatigue.

Some members of MGteam have reported that they experience severe fatigue. “That’s the worst, [being] extremely fatigued,” said one member. “It’s like I can feel it drain out when I’ve done too much. It leaves my face and lowers out my body. If I don’t lie down, I’ll fall down.”

Another study looked at 53 people living with myasthenia gravis. Researchers found that feelings of fatigue were not always connected to muscle weakness. This means that you can experience fatigue even if your myasthenia gravis is well controlled or in remission. It also means that sometimes you may need to look beyond muscle weakness to find out what’s causing fatigue.

Some MGteam members experience both kinds of fatigue. “MG has shown me two very different kinds of fatigue,” explained one. “There’s the fatigue of specific muscles — e.g., I can’t hold my phone up very long. And there is the whole-body fatigue that’s not centered in any particular muscle group, a kind of crushing weariness that’s relieved only by a long night’s sleep.”

Related Conditions That Can Cause Fatigue

People who live with myasthenia gravis have a higher risk for certain other health conditions, too. Some of these can also cause fatigue or make fatigue that you’re already experiencing worse.

Depression

People living with myasthenia gravis are more likely to experience depression, even compared to people living with other autoimmune disorders. Significant tiredness and low energy can be symptoms of depression.

If you find yourself feeling sad, hopeless, or extremely irritable, or if you’ve lost interest in things you used to enjoy, talk to your doctor about being screened for depression. There are a variety of treatments that can improve depression, and these may also help with fatigue.

Lupus

MG and systemic lupus erythematosus (SLE, or simply lupus) might be associated. One study looked at a very large database and found that people living with MG were over 10 times more likely to have lupus than those without MG. Furthermore, it seems that people with MG who underwent thymectomy have a higher chance of developing lupus compared to people with MG who didn’t have thymectomy. Thymectomy is surgery to remove the thymus gland, and it is necessary in some cases of MG.

Fatigue is one common symptom of lupus. Other lupus symptoms include:

• Joint pain
• Fevers you can’t explain
• Rash across your nose and cheeks
• Sensitivity to the sun

If you’re experiencing fatigue along with other potential lupus symptoms, talk to your doctor.

Thyroid Disease

There are a few autoimmune diseases that affect your thyroid, but the one most commonly associated with myasthenia gravis is Graves’ disease. Researchers don’t know exactly how they’re connected. In Graves’ disease, the thyroid produces too much thyroid hormone. This is called hyperthyroidism. Fatigue is a common symptom of hyperthyroidism, especially when the condition isn’t being treated.

One MGteam member with both MG and thyroid disease shared, “Fatigue seems more related to forgetting thyroid meds or disruptions to schedule that keep me from getting things done, which leads to ‘overwhelm’ and fatigue.”

Besides fatigue, Graves’ disease may cause:

• Nervousness or irritability
• Hand tremors
• Unintentional weight loss
• Heart palpitations
• Bulging eyes

If you notice these symptoms, talk to your medical team about whether you may have a thyroid condition in addition to MG.

Rheumatoid Arthritis

Somewhere between 1 percent and 4 percent of people living with myasthenia gravis also have rheumatoid arthritis (RA). RA causes inflammation in your joints and throughout your body. It can cause issues with your heart, lungs, blood vessels, and more.

Fatigue is a common symptom of RA. It can also cause:

• Fevers
• Loss of appetite
• Sore joints that are swollen and warm
• Joint stiffness in the mornings

Let your doctor know if you develop joint pain or other potential symptoms of RA.

Talk to Your Doctor About Muscle Weakness and Fatigue

If you’re still experiencing symptoms of myasthenia gravis (which may include drooping eyelids, double vision, and problems swallowing as well as muscle weakness) despite sticking to your MG treatment plan, it’s important to let your neurology team know. Fatigue may be directly related to MG or caused or worsened by another health problem. Your doctor may order blood tests to check for signs of other autoimmune conditions.

Your doctor may be able to recommend making changes to your treatment plan that can help. They may suggest changing dosage or medications, adding physical or occupational therapy, or getting other health conditions under control. Your quality of life is important, and your health care team can likely help you find ways to feel your best.

Talk With Others Who Understand

MGteam is the social network for people with myasthenia gravis and their loved ones. Members come together to ask questions, give advice, and share their stories with others who understand life with myasthenia gravis.

Do you experience fatigue as well as muscle weakness with myasthenia gravis? Share your experience in the comments below, or start a conversation by posting on your Activities page.