What supplements should you not take with myasthenia gravis?

October 7, 2025 •

4 min read

Intravenous magnesium has been known to trigger a life-threatening myasthenic crisis in patients with myasthenia gravis (MG). For those living with this autoimmune disorder, understanding what supplements should you not take with myasthenia gravis? is crucial for managing symptoms and preventing serious complications.

Quick Summary

This guide details supplements that can worsen myasthenia gravis symptoms or interact dangerously with treatments. It covers key supplements to avoid, such as magnesium, high-dose zinc, creatine, and certain herbal remedies, and stresses the importance of consulting a neurologist.

Key Points

Magnesium is the primary supplement to avoid: High-dose oral magnesium and intravenous magnesium can worsen muscle weakness and trigger a myasthenic crisis in MG patients.
Immune-boosting supplements are risky: Herbal remedies like echinacea and high-dose zinc can stimulate the immune system, potentially worsening MG symptoms.
Creatine may negatively affect muscles: Though used by athletes for strength, creatine can disrupt muscle metabolism and lead to increased fatigue in individuals with MG.
Melatonin and other herbs need caution: Melatonin may interact with immunosuppressants, and other herbal remedies like Huperzine A carry risks for MG patients.
Always consult a healthcare provider: Never start a new supplement without consulting a neurologist or MG specialist, as they can assess individual risks and medication interactions.
Read all labels carefully: Magnesium can be a hidden ingredient in over-the-counter products like laxatives and antacids.

Supplements That Pose the Most Significant Risk

For individuals with myasthenia gravis (MG), the communication between nerves and muscles is already impaired due to the immune system mistakenly attacking neuromuscular junctions. Certain supplements can further disrupt this communication, leading to increased muscle weakness, fatigue, or even a life-threatening myasthenic crisis. The most critical supplement to avoid is magnesium.

Magnesium: The Top Contender for Avoidance

Magnesium is a vital mineral that plays a role in nerve and muscle function, but in the context of MG, too much can be extremely dangerous. It works by inhibiting the release of acetylcholine, the neurotransmitter that promotes muscle contraction.

Amplified Muscle Weakness: For an MG patient, this effect can worsen pre-existing muscle weakness and fatigue.
Interference with Medication: Magnesium can interfere with the effectiveness of common MG medications, such as pyridostigmine (Mestinon), which are designed to boost acetylcholine levels.
Risk of Myasthenic Crisis: Intravenous (IV) magnesium is a known trigger for myasthenic crisis, a medical emergency affecting the breathing muscles. While oral supplements are less potent, high doses should be avoided, and all magnesium supplementation requires a doctor's approval.

Immune-Stimulating Herbs and Minerals

Since MG is an autoimmune disease, any substance that revs up the immune system could potentially worsen symptoms by increasing the autoimmune attack on nerve receptors.

Echinacea: This popular herbal supplement is used for immune support but can increase autoimmune activity, potentially exacerbating MG symptoms. It can also interfere with immunosuppressant drugs used to manage MG.
High-Dose Zinc: While a necessary mineral, high-dose zinc supplementation can boost immune activity, which is undesirable in an autoimmune condition like MG. It can also interfere with immunosuppressive medications like mycophenolate mofetil and azathioprine. Patients should aim to get zinc from food sources, not high-dose supplements.

Supplements That Disrupt Muscle Function

Beyond magnesium and immune-boosters, other supplements can negatively impact muscle function or interfere with MG treatment.

Creatine: Athletes use this supplement to improve muscle strength, but it may disrupt muscle metabolism in MG patients, potentially leading to increased fatigue rather than improvement. Research on creatine's effects in MG is limited, making its use risky.
Melatonin: Used for sleep, melatonin can have an effect on the immune system that might worsen MG symptoms and can interact with corticosteroids and other immunosuppressants.
Huperzine A: Derived from Chinese club moss, this supplement can increase acetylcholine production, but it should only be used short-term and can have side effects that affect MG patients, such as blurred vision and digestive issues. It is important to consult a physician before use.

Comparison of Risky vs. Potentially Safer Supplements

It's important to remember that 'safe' is a relative term, and even supplements that may have potential benefits should only be taken with a doctor's oversight.


Risky Supplements to Avoid/Use with Extreme Caution	Potentially Safer Supplements (With Doctor's Guidance)
Magnesium (High-Dose Oral & IV): Can severely worsen muscle weakness and trigger myasthenic crisis.	Vitamin B12: May support nerve health and reduce fatigue in some MG patients, especially if deficient.
Echinacea: Boosts immune system activity, which can aggravate autoimmune conditions like MG.	Omega-3 Fatty Acids: Have anti-inflammatory properties that may help balance the immune system, but more research is needed.
High-Dose Zinc: Can boost immune function and interfere with immunosuppressants.	Calcium + Recommended Vitamin D: Important for bone health, especially for those on corticosteroids, but high doses of Vitamin D should be avoided.
Creatine: May disrupt muscle metabolism and potentially increase fatigue.	Coenzyme Q10: Some research suggests it supports muscle health, but more studies are needed on its effects in MG.
Melatonin: Potential to affect the immune system and interfere with medications.	L-Carnitine: A few studies suggest it may help with fatigue, but further research is necessary.

Over-the-Counter Medications with Hidden Supplements

Patients with MG must be diligent about reading labels, as some over-the-counter (OTC) products contain high doses of risky supplements. For example, certain laxatives and antacids contain significant amounts of magnesium. Even some proton pump inhibitors, like esomeprazole magnesium (Nexium), contain magnesium. Always ask a pharmacist about the ingredients in any OTC product before purchase.

The Critical Need for Medical Supervision

Supplements are not regulated by the FDA in the same way as prescription drugs, meaning their purity, potency, and potential for contamination can vary widely. The best course of action is always to consult a neurologist or MG specialist before considering any supplement. They can help evaluate the risks and benefits based on your specific health profile, current medications, and MG severity. Carrying a medical alert card that lists risky substances can also protect you in an emergency.

Conclusion

Understanding what supplements should you not take with myasthenia gravis is a cornerstone of patient safety. The risks associated with supplements like magnesium, immune-boosters, creatine, and melatonin can be severe, potentially worsening muscle weakness and interfering with critical MG treatments. While some supplements, like omega-3s and B vitamins, may be beneficial for some patients, none should be taken without explicit medical approval. Open communication with your healthcare team is the most effective way to ensure that any dietary additions do not compromise your health. For comprehensive information on drugs to avoid, the Myasthenia Gravis Foundation of America (MGFA) provides a downloadable list for patients and physicians.(https://myasthenia.org/living-with-mg/mg-emergency-preparedness/cautionary-drugs/)

Frequently Asked Questions

Magnesium can interfere with neuromuscular transmission by inhibiting the release of acetylcholine, the neurotransmitter necessary for muscle contraction. In patients with MG, who already have impaired nerve-muscle communication, this can cause significant muscle weakness and, in severe cases, trigger a life-threatening myasthenic crisis.

Yes, the small amounts of magnesium found naturally in a balanced diet, such as in leafy greens, seeds, and nuts, are generally safe for most MG patients. The primary concern is with high-dose supplements, IV treatments, or medications containing magnesium.

No, immune-boosting supplements should be avoided. Since MG is an autoimmune disease, stimulating the immune system can provoke or worsen the body's attack on its own nerve receptors, leading to a flare-up of symptoms.

Most multivitamins contain only small amounts of magnesium and are considered low-risk, but it's essential to confirm with your doctor first. Some supplements and high doses of certain vitamins can still pose a risk, such as very high doses of Vitamin D.

For MG patients, creatine supplements may have unintended negative effects on muscle metabolism, potentially causing fatigue rather than improving strength. The lack of specific research on creatine's effects in MG makes its use particularly risky.

Melatonin is not recommended for MG patients because it can affect the immune system and potentially interfere with immunosuppressant medications. Discuss safer alternatives for sleep with your doctor.

Always inform any healthcare provider that you have myasthenia gravis. Your MG specialist should weigh the risks and benefits of all treatments, but you should also carry a list of cautionary drugs to proactively inform other physicians. In emergencies, a medical alert card can provide crucial information.

While supplements pose a higher risk due to concentrated doses, some foods and beverages can act as triggers for MG flare-ups in some individuals. Common triggers can include hot foods or beverages and alcohol, though this varies from person to person. Consulting a dietician can help identify and manage any specific food sensitivities.