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Overview: Pyridostigmine is commonly used to treat myasthenia gravis. It works by blocking the breakdown of a natural substance called acetylcholine, which helps your nerves send signals to your muscles. Common side effects include nausea, diarrhea, and stomach cramps.

Uses

What is pyridostigmine used for?

Pyridostigmine is commonly used to treat myasthenia gravis, which is a condition that affects your nerves and muscles.

Pyridostigmine may also be used for other conditions as determined by your healthcare provider.

How does pyridostigmine work (mechanism of action)?

Pyridostigmine works by blocking the breakdown of a natural substance in your body called acetylcholine. This helps your nerves send signals to your muscles to contract.

How is pyridostigmine supplied (dosage forms)?

Brands and other names

  • Mestinon

Dosage forms and strengths

  • 180 mg extended-release oral tablets
  • 60 mg/5 mL oral solution
  • 30 mg, 60 mg oral tablets

How should I store pyridostigmine?

Pyridostigmine should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. 

If you are prescribed pyridostigmine oral tablets, keep them with the silica gel (desiccant) enclosed.

Side Effects

What are the most common side effects of pyridostigmine?

The most common side effects of pyridostigmine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Nausea or vomiting
  • Diarrhea
  • Stomach cramps
  • Increased saliva or mucus
  • Smaller pupil size in your eyes
  • Increased sweating
  • Muscle cramps, twitching, or weakness
  • Skin rash

There may be other side effects of pyridostigmine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of pyridostigmine?

While less common, the most serious side effects of pyridostigmine are described below, along with what to do if they happen.

Severe Allergic Reactions. Pyridostigmine may cause allergic reactions, which can be serious. Stop taking pyridostigmine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Cholinergic Crisis. Pyridostigmine may cause a serious condition called cholinergic crisis. Cholinergic crisis may cause worsening muscle weakness, which could include breathing problems and death. It can be hard to tell if it is different from myasthenic crisis, which happens when your myasthenia gravis gets worse. Get help right away if you have any of the following symptoms of cholinergic crisis.

  • Shortness of breath or trouble breathing
  • Heavy sweating
  • Nausea or vomiting
  • Diarrhea 
  • Increased saliva
  • Increased tears
  • Frequent peeing

Warnings & Precautions

Who should not use pyridostigmine?

Allergies to Ingredients. People who are allergic to any of the following should not take pyridostigmine.

  • Pyridostigmine
  • Mestinon
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific pyridostigmine products they stock.

Kidney Problems. Pyridostigmine should not be taken if your kidneys are not working as well as they should be. If there is a concern about the health of your kidneys, your healthcare provider may do tests to determine if they are working well enough for you to take this medicine.

Gut Blockage. Pyridostigmine should not be taken if you have an intestinal obstruction, which is a blockage in your intestines.

Urinary Blockage. Pyridostigmine should not be taken if you have a urinary obstruction, which is a blockage in your bladder or urinary tract that makes it hard to pee.

What should I know about pyridostigmine before using it?

Do not take pyridostigmine unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share pyridostigmine with other people, even if they have the same condition as you. It may harm them.

Keep pyridostigmine out of the reach of children.

What should I tell my healthcare provider before using pyridostigmine?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if pyridostigmine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Asthma
  • Kidney problems

Pregnancy. It is not known if or how pyridostigmine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant.

Breastfeeding. It is not known if pyridostigmine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take pyridostigmine while breastfeeding.

Other Medicines and Supplements. Pyridostigmine may interact with other medicines and supplements. Before taking pyridostigmine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Interactions

Does pyridostigmine interact with foods or drinks?

There are no known interactions between pyridostigmine and foods or drinks.

It is unknown if drinking alcohol will affect pyridostigmine.

Does pyridostigmine interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using an anticholinergic medicine, which includes antihistamines and medicines commonly used for overactive bladder, Parkinson’s disease, or stomach problems, before taking pyridostigmine.

This may not be a complete list of medicines that can interact with pyridostigmine. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much pyridostigmine?

If you or someone else has used too much pyridostigmine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of pyridostigmine?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.