Taking certain medications can be dangerous if you’re living with myasthenia gravis. Myasthenia gravis can stop the muscles in your face or body from working their best. For this reason, it’s important to make sure your doctors and pharmacist know you have myasthenia gravis, so they can avoid prescribing medications that may make your symptoms worse.

Understanding how certain medications can affect myasthenia gravis is crucial for managing the condition effectively. This article will cover six types of drugs you should avoid if you have myasthenia gravis.

1. Botox

Botulinum toxin, commonly known as Botox, is an injected medication that’s used for many reasons, including:

• Stopping facial wrinkles from forming
• Calming overactive muscles
• Preventing migraine attacks

Botox paralyzes the muscle it’s injected into by stopping the action of a neurotransmitter (chemical messenger) called acetylcholine. For someone with myasthenia gravis, this can be problematic. Acetylcholine works at what’s called the neuromuscular junction between your nerves and muscles to make your muscles move. In myasthenia gravis, acetylcholine does not work as well at the neuromuscular junction, causing muscle weakness and fatigue.

Because both Botox and myasthenia gravis stop acetylcholine from working well, there’s a risk that Botox can worsen a person’s myasthenia gravis. A doctor may still recommend Botox for some conditions if a person’s myasthenia gravis symptoms are mild or moderate.

2. Statins

Statins are a class of drug used to reduce levels of low-density lipoprotein (LDL) cholesterol (“bad” cholesterol) in the arteries. Cholesterol is a type of fat that supports the structure of our arteries. Cholesterol can build up in the arteries, and too much can cause blockages in the arteries. A blockage is dangerous because it can stop blood and oxygen to the heart, causing a heart attack, or to the brain, causing a stroke.

Some commonly used statins are:

• Atorvastatin (Atorvaliq, Lipitor)
• Lovastatin (Altoprev)
• Simvastatin (Flolipid, Zocor)

Several studies have shown that people with myasthenia gravis who take statins have worsening symptoms. In these studies, once people stopped taking the statin, their symptoms generally improved. Researchers also have reported that taking a statin may cause people to develop myasthenia gravis.

Scientists don’t yet know why statins worsen myasthenia gravis symptoms for some people. Statins are important medications, though, and not all people with myasthenia gravis have reactions to them. If you have high cholesterol and are diagnosed with myasthenia gravis, it’s essential to discuss treatment options with your doctor. They may recommend trying a statin while they closely monitor you for symptoms. If your symptoms get worse, they can change your medication.

3. Certain Antibiotics

Antibiotics are important drugs that kill bacteria and fight bacterial infections. There are many classes of antibiotics, and they work in different ways. Different classes of antibiotics target different types of bacteria. Antibiotics can also have unintended effects on our bodies, including for people with myasthenia gravis.

Some antibiotics are fine to take if you have myasthenia gravis. However, some classes of antibiotics can exacerbate (worsen) myasthenia gravis symptoms.

Macrolides

Macrolide antibiotics, such as azithromycin (Zithromax), can worsen myasthenia gravis symptoms like muscle weakness. Azithromycin can stop neuromuscular transmission (the release of acetylcholine) at the neuromuscular junction. Acetylcholine already doesn’t work as well in people with myasthenia gravis, so lowering its function can cause them severe muscle weakness.

Fluoroquinolones

Fluoroquinolone antibiotics, which include ciprofloxacin (Cipro), can make myasthenia gravis symptoms more severe. Fluoroquinolones block acetylcholine action by stopping it from binding to proteins that allow the muscle to contract. This leads to muscle weakness. For fluoroquinolones, this type of muscle weakness can lead to:

• Breathing problems
• Difficulty with swallowing
• Drooping eyelids
• Double vision

Aminoglycosides

Some aminoglycoside antibiotics, like neomycin, may worsen myasthenia gravis symptoms. The risk is higher for people who also have kidney failure. Like macrolides, some aminoglycosides can stop neuromuscular transmission. Other aminoglycosides, like tobramycin, don’t stop neuromuscular transmission. It may be a better choice for people with myasthenia gravis.

4. Heart Rhythm Medications

Heart rhythm medications help the heartbeat regularly. When your heart isn’t beating at a regular pace, your brain and organs might go for periods without enough blood and oxygen. Without enough blood and oxygen, you’re at risk of having a heart attack or stroke.

Beta-blockers and calcium channel blockers are two major classes of medications used to treat irregular or fast heart rhythm.

Calcium Channel Blockers

The calcium channel blockers felodipine and nifedipine both may worsen myasthenia gravis symptoms. Additionally, people who had severe myasthenia gravis were more likely to have been unable to breathe after using nifedipine (Afeditab CR, Procardia) or verapamil (Verelan). Most people recover after they stop taking calcium channel blockers.

Beta-Blockers

There have also been reports of beta-blockers like propranolol (Inderal) worsening myasthenia gravis symptoms for a short period, but then the symptoms improved over time.

Other heart rhythm medications that can worsen myasthenia gravis symptoms include class 1a antiarrhythmics, which include quinidine, disopyramide, procainamide, lidocaine, mexiletine, flecainide, and propafenone.

5. Corticosteroids

Prednisone and other corticosteroids (also simply called steroids) mimic certain hormones in our body. These hormones work to suppress the immune system. When our immune system becomes too active, it can make us sick. Doctors usually prescribe corticosteroids when our immune system is overactive and causing problems.

Corticosteroids can make myasthenia gravis symptoms worse. They’re riskier in older people and those with severe myasthenia gravis. They can be particularly risky if your condition causes problems with swallowing. Like many other drugs, corticosteroids can stop acetylcholine from being effective at the neuromuscular junction.

6. Immunotherapy Drugs for Cancer

Drugs called immune checkpoint inhibitors (ICIs) are commonly used for cancer treatment. They encourage the immune system to fight cancer. Common ICIs include:

• Avelumab (Bavencio)
• Atezolizumab (Tecentriq)
• Nivolumab (Opdivo)
• Pembrolizumab (Keytruda)

In some cases, ICIs can lead to severe myasthenia gravis side effects or even cause people without myasthenia gravis to develop the condition. Symptoms that are particularly exacerbated by ICIs are:

• Muscle weakness
• Double vision
• Eyelid drooping

In myasthenia gravis, the immune system makes proteins called antibodies that block acetylcholine from binding to proteins that allow the muscles to contract. This makes muscles weak and unable to work normally. ICIs can trigger the immune system to make more of those antibodies. When myasthenia gravis is triggered by ICIs, it may be a life-threatening situation.

Consult With Your Doctor

Many of the medications listed here are life-saving medications, and there may be situations when you need to take them. Everyone’s medical history is different, and you may not react the same to a medication as others.

Make sure that your health care providers have a current list of all the medications you take — including any supplements like magnesium — and are informed that you’ve been diagnosed with myasthenia gravis. Finding the right medication involves teamwork between you, your doctors, and your specialists to keep you healthy and minimize risks.

Find Your Team

On MGteam, the social network for people living 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.

Which medications your doctor has advised you to avoid? Have you taken medications that made your myasthenia gravis symptoms worse? Share your experience in the comments below, or start a conversation by posting on your Activities page.