Magnesium is essential for good health. But magnesium supplements or medications aren’t right for everyone. If you’re living with myasthenia gravis (MG), you’ll need to be careful about getting too much magnesium because it can affect your nerve and muscle function. It may also interfere with your current treatment plan.

Before you head to the supplement aisle, here are some important tips you should know.

1. Magnesium Is an Essential Nutrient

Magnesium is an important mineral that has multiple roles throughout the body. It supports the work of 300 different enzymes responsible for various tasks, such as:

• Blood pressure control
• Blood sugar regulation
• Bone development
• Energy production
• Heart rhythm maintenance
• Protein synthesis
• Muscle contraction
• Nerve signaling

People with certain health conditions, such as heart disease, type 2 diabetes, osteoporosis, and migraine, may benefit from a little extra magnesium. However, taking magnesium supplements isn’t always better for your health.

2. Magnesium Can Cause a Myasthenic Crisis

A myasthenic crisis is an emergency that affects a small percentage of people with MG. It’s a life-threatening condition that impairs breathing and requires medical intervention. Magnesium sulfate is known to trigger myasthenic crises. For this reason, doctors recommend that people with MG avoid magnesium supplements or drugs that contain magnesium such as muscle relaxants, beta-blockers, or calcium channel blockers.

During a myasthenic crisis, the muscles that help you breathe become too weak to properly move air in and out of your lungs. Because you cannot breathe on your own, you may need mechanical ventilation, a machine to support your lungs until your symptoms improve.

Although this effect is scary, it’s unusual to have this type of extreme muscle weakness when taking magnesium by mouth. The biggest threat for people with MG is when intravenous magnesium therapies are given, meaning it’s delivered directly into the bloodstream through a tube in a medical setting. Carrying a medical card that notifies people that you have MG and lists potential interactions can help keep you safe from potentially dangerous medical mistakes.

3. Magnesium Interferes With Certain Medications

Myasthenia gravis is an autoimmune disease, meaning the body’s immune system mistakenly attacks its own cells. In this case, it targets the connections between nerves and muscles, which can cause muscle weakness and fatigue.

People with MG may take various medications to manage their autoimmune condition along with any other existing health issues. Sometimes, magnesium stops medications from being absorbed or can cause dangerous side effects when taken together.

Magnesium interacts with the following drugs:

• Antibiotics — Demeclocycline (Declomycin), doxycycline (Vibramycin), ciprofloxacin (Cipro), and levofloxacin (Levaquin)
• Bisphonates — Medication for osteoporosis, such as alendronate (Fosamax)
• Diuretics, also called water pills — Furosemide (Lasix), bumetanide (Bumex), hydrochlorothiazide (Aquazide H), ethacrynic acid (Edecrin), amiloride (Midamor), and spironolactone (Aldactone)
• Proton pump inhibitors — Esomeprazole magnesium (Nexium) and lansoprazole (Prevacid)

This short list doesn’t fully cover everything you should avoid with magnesium. Keep track of your medications and supplements and share this list with everyone involved in your health care decisions to avoid interactions and get the best care.

4. Food Can Provide Enough Magnesium

Eating a healthy and varied diet is the best way to give your body all the necessary nutrients, including magnesium. With food, you’re less likely to get an isolated high dose of one specific nutrient that may negatively affect your MG symptoms or treatment plan. Fortunately, many foods can provide a safe and healthy dose of magnesium.

Nuts and seeds are some of the best sources of magnesium and other minerals. Specifically, pumpkin seeds, chia seeds, almonds, cashews, and peanuts supply at least 15 percent of the recommended daily value for magnesium per serving. Other good sources include cooked spinach, shredded wheat cereal, soymilk, and black beans.

5. Magnesium Is Stored in the Body

Based on a blood test, it’s not easy to tell if someone has a magnesium deficiency. Most of the body’s magnesium is stored in the bones and soft tissues. The kidneys tightly regulate magnesium blood levels, excreting less in the urine when levels are low.

While eating nutritious foods containing magnesium is important, most people don’t need to worry about getting enough every day. The body absorbs about 30 percent to 40 percent of the magnesium consumed in food and beverages. Depending on your needs, your body may absorb more magnesium or eliminate less magnesium to regulate your levels.

6. Some Medications Contain Magnesium

People with MG should always check the labels on medications not prescribed by their usual doctor. Magnesium is a major ingredient in several over-the-counter drugs, including laxatives and heartburn medications. Even when you avoid magnesium supplements, you can accidentally get a high dose from these products.

If you’re unsure, you can always ask the pharmacist if the product you’re buying has magnesium in it. Milk of Magnesia and Rolaids are two examples of over-the-counter products that contain magnesium. Multivitamins usually provide magnesium as well. Most people with MG can still safely use these products, but it’s always best to run it by your MG health care provider first.

7. Supplements May Not Be Safe, so Seek Your Doctor’s Approval

The dietary supplement industry may have you believe that the more supplements you take, the healthier you’ll be. However, that’s not the case. Supplements can be harmful when they’re not needed or if they interfere with your medical conditions or medications.

People with rare diseases like MG need to be especially cautious before taking supplements. Always ensure your health care providers know about your medical history and medications. Because not many people are familiar with the management of MG, speaking to your neurologist is the best way to decide if supplements are right for you.

Find Your Team

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

Have you ever had adverse effects from magnesium? Did you experience worsening muscle weakness or respiratory failure? Share your story in the comments below, or start a conversation by posting on your Activities page.