Myasthenia gravis (MG) is a long-term condition where the immune system mistakenly attacks the connection between nerves and muscles. This weakens muscles and makes them tire more easily. If you or a loved one is living with MG, you may wonder whether vitamins and supplements can help — or if they might make symptoms worse. The answer isn’t straightforward, as some supplements can interfere with medications or contribute to worsening symptoms.

In this article, we’ll cover six vitamins and supplements that may aggravate MG symptoms, along with nutrients that could help support muscle function and overall health.

1. Magnesium

Magnesium helps muscles relax, but for people living with MG, this can be a problem. Since MG already causes muscle weakness, too much magnesium can make symptoms worse. In some cases, magnesium supplementation even trigger a myasthenic crisis, a serious condition where the muscles used for breathing become too weak to work properly.

Magnesium can reduce how well pyridostigmine (Mestinon), a common MG medication that helps muscles contract. Because magnesium works against this process, it can interfere with symptom management.

The biggest concern is intravenous (IV) magnesium, which is sometimes given in hospitals for other conditions. However, most people with MG don’t need to avoid magnesium-rich foods like nuts, seeds, and dark leafy greens, or the small amounts found in multivitamins. If you’re considering a magnesium supplement, talk to your doctor to make sure it’s safe for you.

2. Too Much Vitamin D

Vitamin D is important for strong bones and supporting your immune system. However, taking too high a dose of vitamin D supplements can lead to hypercalcemia (high calcium levels in the blood). High blood calcium levels can cause muscle weakness, which people with MG are already more likely to experience.

People taking corticosteroids like prednisone for MG may have a higher risk of hypercalcemia if they take high doses of vitamin D supplements. While moderate amounts of vitamin D can be beneficial, it’s important to stick to the recommended daily amount. Check with your doctor before taking high doses (more than 4,000 international units daily).

Taking too much vitamin D for a long time can lead to kidney problems, so it’s best to follow your doctor’s guidance to ensure you’re getting a safe and effective amount.

3. Zinc

Zinc is often recommended to support the immune system, but since MG is an autoimmune disease (where the immune system attacks the body by mistake), boosting immune activity could make symptoms worse.

Zinc can interfere with immunosuppressants like mycophenolate mofetil (CellCept) or azathioprine (Imuran). These medications help manage MG symptoms by calming the immune system. Avoid high-dose zinc supplements (more than 40 milligrams daily for adults) unless your doctor specifically recommends them.

Zinc is an important nutrient, but people with MG should try to get it from foods like legumes, shellfish, meat, and poultry. You should skip high-dose zinc supplements unless a doctor recommends it due to a deficiency or specific dietary needs.

4. Echinacea

Echinacea is a common herbal supplement for immune support. It’s found in teas, immune-support supplements, and some cold and flu remedies. However, because echinacea stimulates the immune system, it may worsen MG symptoms by increasing autoimmune activity (when the body mistakenly attacks its own nerve receptors).

Echinacea may also interfere with immunosuppressive drugs, potentially making them less effective. Instead of relying on echinacea, those with MG can focus on eating a nutrient-rich diet, getting enough sleep, and practicing good hygiene to support the immune system.

Some herbal blends and teas include echinacea without clearly listing it, so always check supplement labels carefully before taking them.

5. Melatonin

Melatonin is a popular supplement for sleep support, but it can also affect the immune system, which may worsen MG symptoms.

Melatonin can interact with corticosteroids and immunosuppressants, potentially making them less effective. If you have trouble sleeping, try alternatives like:

• Keeping a regular sleep schedule
• Limiting screen time before bed
• Talking to your doctor about safer options

6. Creatine

Creatine is a compound found in red meat and fish. Creatine supplements are commonly used by athletes to build muscle strength and improve performance. For people with MG, however, it may disrupt muscle metabolism, potentially leading to fatigue rather than strength improvement.

There isn’t much research on how creatine affects MG, but since the condition already affects muscle function, making unnecessary changes in how the body uses energy could be risky. One small case study found positive results for a 26-year-old man with MG using creatine alongside exercise. However, larger studies are necessary to support safe use in people with MG. If you want to build strength, a physical therapist can help create a safe exercise plan that fits your needs.

If you’re looking to build strength, working with a physical therapist can help you create a safe and effective exercise plan tailored to your needs.

6 Vitamins That May Help MG

Certain vitamins and nutrients may offer benefits for people living with MG. However, it’s important to talk to your neurologist or another healthcare provider before adding any supplements to your routine to ensure they are safe and appropriate for you.

1. Vitamin B12

Vitamin B12 supports nerve health and energy production, which may help reduce fatigue and keep the nervous system functioning properly. Some people with MG may have low B12 levels, so taking a supplement — or eating more food rich in vitamin B12, like meat, fish, dairy, and eggs — could be helpful.

2. Omega-3 Fatty Acids

Omega-3 fatty acids help lower inflammation, support immune balance, and promote heart health. They may also protect and maintain nerve cells, which could be helpful for people with MG. Good food sources of omega-3s include salmon, flaxseeds, and walnuts.

3. Calcium and Recommended Doses of Vitamin D

Calcium and vitamin D work together to keep bones strong, which is especially important for people with MG who take long-term corticosteroids (such as prednisone), as these medications can increase the risk of osteoporosis (bone loss).

4. Coenzyme Q10

Enzymes are proteins that help chemical reactions in the body. Coenzyme Q10 (CoQ10) is a natural compound that plays a role in energy production and muscle function. Some research suggests it may help with muscle health, but more studies are needed to confirm its effects on MG.

5. L-Carnitine

L-carnitine is an amino acid (a building block of protein) that helps move fatty acids into the mitochondria (the part of cells that makes energy). A small case study suggests it may help with muscle weakness and fatigue in people with MG, but more research is needed.

6. Curcumin

Curcumin (turmeric extract) is a strong anti-inflammatory compound that may help with autoimmune conditions by balancing the immune system and reducing swelling and irritation in the body. While more research is needed on its effects in MG, curcumin’s ability to lower inflammation may offer potential benefits.

Turmeric can also be used as a spice to add flavor to foods and beverages, providing a natural way to incorporate curcumin into your diet.

Use Supplements With Guidance and Care

Although some supplements may offer health benefits, they also come with potential risks, especially for people with MG. Supplements can interact with medications, overstimulate the immune system, or cause unintended side effects, making it crucial to consult a healthcare provider or registered dietitian before adding them to your routine.

Additionally, unlike prescription medications, supplements are not strictly regulated by the U.S. Food and Drug Administration (FDA), meaning their quality, purity, and potency can vary between brands. To reduce the risk of contamination or misleading ingredient claims, choose reputable brands that undergo third-party testing from reputable organizations. Your healthcare team can help you determine which supplements, if any, are safe and appropriate for your individual needs.

Talk With Others Who Understand

MGteam is the social network for people with myasthenia gravis and their loved ones. On MGteam, more than 2,500 members come together to ask questions, give advice, and share their stories with others who understand life with the condition.

Have you wondered which vitamins might help with MG? Share your experience in the comments below, or start a conversation by posting on your Activities page.