What Is Pyridostigmine and How Does It Work?

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

Pyridostigmine is available under the following different brand names: Mestinon and Regional.

What Are the Dosages of Pyridostigmine?

Dosages of Pyridostigmine:

Dosage Forms and Strengths

Injection solution

  • 5 mg/mL

Tablet, controlled release

  • 180 mg


  • 60 mg


  • 60mg/5mL (240mL)

Dosage Considerations – Should be Given as Follows:

Myasthenia Gravis

  • Adults: Tablets/syrup: 600 mg/day spaced to provide maximum relief
  • Adults: Sustained-release: 180-540 mg orally once/day or every 12 hours; not to exceed 1.5 g/day
  • Children
    • 7 mg/kg/day orally divided every 4 hours
    • 0.05-0.15 mg/kg intravenously/intramuscularly (IV/IM) every 4-6 hours; not to exceed 10 mg/dose
  • Neonates
    • 5 mg orally every 4-6 hours
    • 0.05-0.15 mg/kg IV/IM every 4-6 hours; not to exceed 10 mg/dose

Reversal of Nondepolarizing Muscle Relaxants


  • 0.1-0.25 mg/kg/dose
  • 10-20 mg generally effective; full recovery may occur as early as less than 15 minutes but may require greater than 30 minutes
  • To minimize side effects 0.6-1.2 mg intravenously (IV) atropine sulfate is recommended immediately before pyridostigmine


  • 0.1-0.25 mg/kg/dose intravenously (IV)
  • Dosing range: 0.1-0.25 mg/kg/dose; full recovery may occur as early as less than 15 minutes but may require greater than 30 minutes

Pretreatment for Soman Nerve Gas Exposure

  • 30 mg orally every 8 hours beginning several hours before exposure
  • Discontinue at the first sign of nerve agent exposure then begin atropine and pralidoxime

What Are Side Effects Associated with Using Pyridostigmine?

Pyridostigmine has fewer gastrointestinal (GI) effects than neostigmine.

Common side effects of Pyridostigmine include:

  • Abdominal cramps
  • Cardiac standstill (rare)
  • Cholinergic crisis (rare)
  • Cholinergic effects (nausea/vomiting, increased peristalsis, increased salivation, urinary frequency)
  • Convulsions
  • Decreased pupil size
  • Diarrhea
  • Drowsiness
  • ECG changes
  • Hives
  • Increased mucus
  • Increased sweating or cold sweat
  • Irregular heartbeat (arrhythmia)
  • Laryngospasm
  • Loss of consciousness
  • Low blood pressure (hypotension)
  • Pale skin
  • Rash or itching
  • Slow heart rate
  • Thrombophlebitis
  • Transient rash in bromide-sensitive patients
  • Upset stomach
  • Warmth or tingly feeling
  • Watery eyes
  • Weakness

Serious side effects of pyridostigmine include:

  • New or increased muscle cramps/weakness/twitching
  • Shortness of breath
  • New or increased difficulty swallowing
  • Slow heartbeat
  • Dizziness
  • Headache

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Pyridostigmine?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more information about this medicine.

What Are Warnings and Precautions for Pyridostigmine?


  • Therapy must be administered by trained personnel.
  • This medication contains pyridostigmine. Do not take Mestinon or Regonol if you are allergic to pyridostigmine or any ingredients contained in this drug.
  • Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


  • Hypersensitivity
  • Mechanical intestinal or urinary obstruction

Males must use latex condoms during any sexual contact with women of childbearing potential even after undergoing successful vasectomy

Effects of Drug Abuse

Short-Term Effects

  • See "What Are Side Effects Associated with Using Pyridostigmine?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Pyridostigmine?"


Pregnancy and Lactation

  • Pyridostigmine may be acceptable for use during pregnancy. Either animal studies show no risk but human studies are not available or animal studies showed minor risks and human studies were done and showed no risk.
  • Pyridostigmine is compatible with breastfeeding.
Medscape. Pyridostigmine.
RxList. Mestinon Side Effects Drug Center.

Health Solutions From Our Sponsors