Pyridostigmine

1 medicine

Pyridostigmine is a reversible acetylcholinesterase inhibitor used mainly for myasthenia gravis; taking too much can cause a cholinergic crisis with worsening weakness and breathing difficulty.

Mestinon

Pyridostigmine

60mg

Mestinon is a neurology medication containing Pyridostigmine, available as 60mg tablets.

from $1.66 / tablet View

Key facts

  • Pyridostigmine (sold as Mestinon) is a reversible acetylcholinesterase inhibitor. It slows the breakdown of acetylcholine at the nerve-muscle junction, strengthening the signal that tells muscles to contract.
  • It is usually taken 2 to 4 times a day, timed to cover the periods when you need muscle strength most; your prescriber sets an individual schedule and dose.
  • Taking more than prescribed can cause a cholinergic crisis: worsening muscle weakness together with excess saliva, sweating, cramping, and nausea that can progress to breathing difficulty. This is a medical emergency.
  • Seek urgent care for rapidly spreading weakness, trouble breathing or swallowing, or a very slow heartbeat.

What pyridostigmine treats

Pyridostigmine treats myasthenia gravis, an autoimmune condition where antibodies block signals between nerves and muscles, causing drooping eyelids, double vision, and weakness that worsens with activity. It improves muscle strength and endurance but does not cure the underlying disease.

How pyridostigmine works

Nerves release acetylcholine to tell muscles to contract, and an enzyme called acetylcholinesterase normally breaks this down within moments. Pyridostigmine blocks that enzyme temporarily, so acetylcholine lingers longer at the junction between nerve and muscle. This gives a connection weakened by myasthenia gravis more chance to trigger a contraction.

Before you take it

  • Tell your prescriber about asthma, chronic obstructive pulmonary disease, urinary or intestinal blockage, or a slow heart rate; these need caution.
  • Mechanical obstruction of the gut or urinary tract is a contraindication, since increased muscle activity can worsen it.
  • Mention other medicines that affect acetylcholine, including some anaesthetics and antibiotics, since they can weaken pyridostigmine's effect or add to its side effects.
  • Discuss any new medicine with your prescriber before starting it, including over-the-counter cold and allergy remedies with anticholinergic effects.

Side effects

Common effects relate to increased acetylcholine activity: nausea, stomach cramps, diarrhoea, excess saliva or sweating, and muscle twitching.

Stop and seek urgent medical care for any of these:

  • Increasing muscle weakness or difficulty breathing, especially if it comes on quickly.
  • Severe abdominal cramping with vomiting or diarrhoea.
  • A very slow heartbeat, fainting, or marked dizziness.
  • Signs of an allergic reaction: rash, facial swelling, or wheeze.

Safety essentials

  • Never take an extra or early dose to treat worsening weakness without medical advice; too much pyridostigmine causes a cholinergic crisis whose weakness can look identical to the disease itself but needs the opposite treatment.
  • If breathing becomes difficult or swallowing becomes unsafe, treat this as an emergency and get to a hospital immediately.
  • Keep to your prescribed dosing schedule; skipping or doubling doses destabilises muscle strength.
  • Carry information about your diagnosis and medicine, since emergency staff need to know you take a cholinesterase inhibitor.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.