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Generic name: pyridostigmine [ py-rid-o-STIG-meen ]
Brand names: Mestinon, Mestinon Timespan, Regonol
Dosage forms: oral syrup (60 mg/5 mL), oral tablet (60 mg), oral tablet, extended release (180 mg)
Drug class: Cholinergic muscle stimulants

Medically reviewed by on Nov 9, 2023. Written by Cerner Multum.

What is pyridostigmine?

Pyridostigmine affects chemicals in the body that are involved in the communication between nerve impulses and muscle movement.

Pyridostigmine is used to treat the symptoms of myasthenia gravis. It is also used in military personnel who have been exposed to nerve gas.

Pyridostigmine may also be used for purposes not listed in this medication guide.

Pyridostigmine side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using pyridostigmine and call your doctor at once if you have any of these serious side effects:

Common side effects of pyridostigmine may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


You should not use pyridostigmine if you you have a bladder or bowel obstruction.

Before taking this medicine

You should not use pyridostigmine if you are allergic to it, or if you have a bladder or bowel obstruction.

To make sure you can safely take pyridostigmine, tell your doctor if you have any of these other conditions:

FDA pregnancy category C. It is not known whether pyridostigmine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using pyridostigmine.

It is not known whether pyridostigmine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Pyridostigmine is not approved for use by anyone younger than 18 years old.

How should I take pyridostigmine?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take this medicine with food or milk if it upsets your stomach.

Do not crush, chew, or break an extended-release tablet. Swallow it whole.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

The amount and timing of this medicine is extremely important to the success of your treatment. Carefully follow your doctor's instructions about how much medicine to take and when to take it.

Your doctor may occasionally change your dose to make sure you get the best results. You may be asked to keep a daily record of when you took each dose and how long the effects lasted. This will help your doctor determine if your dose needs to be adjusted.

If you need surgery, tell the surgeon ahead of time that you are using pyridostigmine. You may need to stop using the medicine for a short time.

Store at room temperature away from moisture and heat.

Keep the tablets in their original container, along with the canister of moisture-absorbing preservative that comes with this medicine.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, diarrhea, stomach cramps, sweating, blurred vision, drooling, and weak or shallow breathing.

Worsening muscle weakness, or no change in your myasthenia gravis symptoms, may also be signs of overdose.

What should I avoid while taking pyridostigmine?

This medication may cause blurred vision or impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Drinking alcohol can increase certain side effects of pyridostigmine.

What other drugs will affect pyridostigmine?

Other drugs may interact with pyridostigmine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Popular FAQ

Mestinon (pyridostigmine) has been used to treat postural tachycardia syndrome (POTS) and may improve symptoms such as a fast heart rate (tachycardia) and symptom burden (Raj et al., 2005). However, research that investigated the addition of Mestinon to standard beta-blocker treatment (propranolol or bisoprolol) found no additional advantage with the addition of Mestinon and suggested beta-blocker therapy alone to be the preferred option (Moon et al., 2018) Continue reading

Mestinon is a common treatment for myasthenia gravis but 25% of all patients who take it discontinue it because of side effects, and many discontinue it because it does not make any difference to their symptoms. Because it is short-acting, it could theoretically be stopped without tapering it, but you should always talk to your doctor about stopping it before you do so. Continue reading

Mestinon is a prescription medicine that can help relieve symptoms of myasthenia gravis (MG) such muscle weakness, double vision, blurred vision, drooping eyelids, loss of facial expressions, and difficulties with talking, chewing food, swallowing and breathing. There is no cure for MG, but treatments can help with symptoms. Continue reading

Mestinon (pyridostigmine) works by slowing down the breakdown of the chemical messenger acetylcholine at the neuromuscular junction which helps to improve muscle strength by increasing the signals between nerves and muscles. Continue reading

Mestinon is not an immunosuppressant it is an anticholinesterase inhibitor that slows the breakdown of acetylcholine in the space between nerves and muscles. This helps improve muscle strength by making the signal between nerves and muscles stronger. Mestinon does not affect your immune system, but it is used for autoimmune conditions, such as myasthenia gravis, a neuromuscular disease. It may be also be used off-label to treat postural orthostatic tachycardia syndrome (POTS). Continue reading

View more FAQ

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.