What Is Pyridostigmine? Uses, Dosage, and What You Need to Know in 2026

Pyridostigmine is a prescription medication that has been treating myasthenia gravis for over 70 years. Despite its long history, many patients receive a prescription without a full understanding of what the drug does, how to take it correctly, and what to watch for. This guide covers the essentials.

What Is Pyridostigmine?

Pyridostigmine bromide is a cholinesterase inhibitor — a type of drug that works by blocking the enzyme (acetylcholinesterase) responsible for breaking down acetylcholine, a chemical that carries signals from nerves to muscles. By preserving more acetylcholine at the neuromuscular junction, Pyridostigmine strengthens the nerve-to-muscle signal.

It is sold under the brand names Mestinon (by Bausch Health), Mestinon Timespan (extended-release version), and Regonol (an injectable form). Generic Pyridostigmine tablets are widely manufactured. The drug has been in clinical use since 1955 and is on the World Health Organization's List of Essential Medicines.

What Is Pyridostigmine Used For?

Pyridostigmine has several FDA-approved and off-label uses:

Myasthenia gravis (primary FDA-approved use): Pyridostigmine is the most commonly used first-line symptomatic treatment for MG. It improves muscle strength by allowing more acetylcholine to accumulate at muscle receptor sites.

Reversal of neuromuscular blockade: Used by anesthesiologists to reverse the effects of nondepolarizing muscle relaxants (paralytics) used during surgery.

Military nerve agent pre-exposure prophylaxis: FDA-approved for use by military personnel as a pre-exposure treatment before expected contact with the nerve agent Soman. Used in conjunction with atropine and pralidoxime.

POTS (off-label): Used off-label for postural orthostatic tachycardia syndrome to improve autonomic nerve function and reduce upright heart rate.

Underactive bladder (off-label): May be used in some patients with neurogenic bladder to improve bladder contraction.

Available Forms and Strengths

Pyridostigmine is available in three oral forms:

60 mg immediate-release (IR) tablets: Start working in 15–30 minutes; effects last 3–6 hours. Most widely available and most affordable. Taken multiple times daily.

180 mg extended-release (ER) tablets (Mestinon Timespan): Slower, more uniform release; taken once or twice daily (at least 6 hours apart). Duration of effect averages 2.5 times that of the IR tablet. Currently in limited supply.

60 mg/5 mL oral solution (syrup): Raspberry-flavored liquid containing 60 mg per teaspoon. Useful for patients with swallowing difficulties or those who need precise dose adjustments (including children).

What Is the Typical Dose of Pyridostigmine?

Pyridostigmine dosing is highly individualized. There is no universal dose — your neurologist will titrate based on symptom control and side effects. Typical starting ranges:

IR tablets: Starting dose often 30–60 mg three times daily while awake. May be increased to 60 mg every 3–4 hours as needed. Total daily doses above 300 mg raise cholinergic crisis risk.

ER tablets: One tablet (180 mg) once or twice daily, at least 6 hours apart.

Do not adjust your dose without speaking to your doctor. Both too little and too much Pyridostigmine can cause muscle weakness.

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How to Take Pyridostigmine

Take by mouth with or without food (food may help reduce stomach upset)

Swallow ER tablets whole — do not crush, cut, or chew them

For the oral solution, use a medical measuring device — not a household teaspoon

Store at room temperature (77°F / 25°C). Keep tablets in a dry place — the ER tablets are hygroscopic (absorb moisture) and should be stored with the enclosed silica gel packet

Who Should Not Take Pyridostigmine?

Pyridostigmine is contraindicated in patients with:

Mechanical intestinal obstruction

Mechanical urinary obstruction

Known allergy to pyridostigmine or bromides

Use with caution in patients with bronchial asthma, renal impairment, or cardiac arrhythmias.

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Is Pyridostigmine a Controlled Substance?

No. Pyridostigmine is not a DEA-scheduled controlled substance. There are no special prescription restrictions related to controlled substance scheduling. Any licensed prescriber can prescribe it, and there are no limits on refills based on controlled substance status.

Finding Pyridostigmine in 2026

The 180 mg ER formulation has been difficult to find at many pharmacies since 2024. If you're having trouble filling your prescription, medfinder.com can contact pharmacies near you to find which ones have your specific formulation in stock.

For more detail on managing Pyridostigmine side effects, see our guide to Pyridostigmine side effects and what to expect.