A cholinesterase inhibitor used to improve muscle strength in myasthenia gravis.
Drug Class: cholinesterase-inhibitor
Pyridostigmine (brand name Mestinon) is a medication that improves communication between nerves and muscles. It's the primary symptomatic treatment for myasthenia gravis, helping to improve muscle strength including the muscles controlling the eyelids and eye movements.
Key Takeaways
- Improves nerve-muscle communication
- First-line symptom treatment for myasthenia gravis
- Works within hours—but effects wear off
- Doesn't treat underlying disease—just symptoms
- Dosing must be carefully balanced
How It Works
In myasthenia gravis, antibodies attack the neuromuscular junction, reducing the effect of acetylcholine. Pyridostigmine inhibits acetylcholinesterase, the enzyme that breaks down acetylcholine. This increases acetylcholine levels and improves muscle contraction.
Common Uses
- Myasthenia gravis—symptomatic treatment
- Improves ptosis and double vision
- Helps with weakness and fatigue
Dosing
- Usually starts at 60mg three times daily
- Effects begin within 30-60 minutes
- Last about 3-4 hours
- Extended-release (Mestinon Timespan) available for overnight
- Dose adjusted based on symptoms
Side Effects
Common (Cholinergic Effects)
- Abdominal cramps
- Diarrhea
- Increased salivation
- Sweating
- Nausea
Signs of Over-Dosing (Cholinergic Crisis)
Seek immediate care if you experience: severe weakness (especially breathing difficulty), excessive secretions, severe diarrhea, slow heart rate. This may indicate too much medication.
Tips for Taking Pyridostigmine
- Take 30-60 minutes before meals or activities
- Time doses to cover your weakest periods
- Take with food if stomach upset occurs
- Carry medication with you
- Space doses to avoid peaks and troughs
Important Considerations
- Symptomatic treatment only—doesn't modify disease
- Usually combined with immunosuppressive therapy
- Effects vary throughout the day
- Dose requirements may change over time
Frequently Asked Questions
How quickly will it work?
Effects typically begin within 30-60 minutes and last 3-4 hours. You should notice improvement in ptosis and strength.
Why do I still have symptoms?
Pyridostigmine improves but may not eliminate symptoms. Most myasthenia patients need additional immunosuppressive therapy to control the underlying disease.
What if I miss a dose?
Take it as soon as you remember, then resume your regular schedule. Don't double up on doses.
Can I adjust my own dose?
Work with your doctor on dosing. Taking too much can actually worsen weakness (cholinergic crisis), so increases should be done carefully.
Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice.
Medically Reviewed Content
This article meets our editorial standards
- Written by:
- Hashemi Eye Care Medical Team
- Medically reviewed by:
- Board-Certified Neuro-Ophthalmologist (MD, Neuro-Ophthalmology)
- Last reviewed:
- January 30, 2025