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Pyridostigmine
General Information
Pyridostigmine (generic name: pyridostigmine) is a reversible acetylcholinesterase inhibitor. It is primarily prescribed to treat myasthenia gravis, an autoimmune disease that leads to muscle weakness and fatigue. Pyridostigmine works by increasing the strength of nerve signals to damaged muscle areas. It achieves this by preventing the breakdown of acetylcholine, a chemical messenger necessary for proper nerve-to-muscle communication. By maintaining higher acetylcholine levels, pyridostigmine helps reduce muscle weakness.
In addition to myasthenia gravis, pyridostigmine has been used off-label to manage symptoms of other conditions such as Postural Orthostatic Tachycardia Syndrome (POTS), where it helps alleviate rapid heart rate and stabilize blood pressure upon standing. It has also been explored as a treatment option for certain symptoms of Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), particularly those related to autonomic dysfunction, exertional tolerance, and muscle fatigue.
Dosing and Monitoring Instructions
Please carefully follow your dosing instructions in your RTHM dashboard. Take this medication with food or milk to avoid stomach upset.
Pyridostigmine can lower your heart rate and sometimes affect blood pressure. We recommend checking your blood pressure and heart rate the day before and after a dose change. Your heart rate should be above 65 bpm and your blood pressure should be above 100/60 for you to proceed with any dose increase.
If you’re on a stable dose of pyridostigmine, check your blood pressure and heart rate at least once a month.Your heart rate should be above 60 bpm and your blood pressure should be above 90/60.
Please read this treatment guide in its entirety for additional important information.
What To Do If I Miss a Dose
  • Read the medication guide provided by your pharmacist before you start taking pyridostigmine. If you have any questions, log into the dashboard and message the RTHM Medical Team.
  • Take your pyridostigmine at the same time each day.
  • Do not increase or decrease your dosage or stop taking this medication without talking to your medical provider first.
  • You should not take pyridostigmine if you have kidney impairment, urinary or bowel blockages including an enlarged prostate, heart disease, lung disease, glaucoma, have cancer, are pregnant, planning to become pregnant or breastfeeding.
  • Be careful when driving a car or using machinery any time you start a new medication or increase your dosage.
Potential Side Effects
For some medications, it’s common to experience mild side effects as your body adjusts during the first few months of use. Mild side effects can occur when taking pyridostigmine. These side effects can include:
  • Digestive issues including nausea, vomiting, diarrhea, and abdominal cramps
  • Increased saliva production
  • Increased mucus production
  • Symptoms of peristalsis (digestive muscle contractions) which can include trouble swallowing, heartburn, and chest pain
  • Increased sweating
  • Muscle cramping or twitching
  • Blurred vision
  • Increased urination
  • Fatigue
  • Mild allergic reactions
  • Muscle weakness
  • Anxiety
  • Watery eyes
When to Seek Medical Attention
Take medication only as directed. In the event of an accidental overdose, contact emergency services immediately.
Serious side effects with pyridostigmine are not common, but they can occur. If you experience any of these symptoms, call your healthcare provider right away or seek emergency medical care.
  • Cholinergic crisis - this is a condition that develops when there is too much pyridostigmine in the body, often the result of poor kidney function. Symptoms can include urinary incontinence, muscle cramps, twitches or weakness, pinpoint pupils, excessive sweating, seizures, slurred speech, confusion
  • Severe allergic reactions causing severe swelling and difficulty breathing
  • A slowed heart rate that leads to lightheadedness or severe fatigue
  • Syncope (fainting)
  • Severe GI disruption - severe vomiting or diarrhea can impact your body’s ability to regulate electrolyte levels
  • Serious changes in mood and behavior including, but not limited to, hallucinations, suicidal ideations and cognitive impairment.
  • Blurred vision
Interactions with Pyridostigmine
  • You should not take pyridostigmine if you are taking:
    • Anticholinergics, such as atropine
    • Other acetylcholinesterase medications such as donepezil (Aricept), galantamine (Razadyne), and rivastigmine (Exelon)
  • You should be cautious when taking pyridostigmine with the following medications. If your provider wants to start you on any of these medications, make sure to tell your provider you are taking pyridostigmine.
    • Tricyclic antidepressants, such as amitriptyline, can make pyridostigmine less effective
    • Corticosteroids, such as prednisone and methylprednisolone, can block the effect of pyridostigmine
    • Diphenhydramine (Benadryl and contained in Nyquil) can lower pyridostigmine’s effectiveness
    • Beta-blockers, such as propranolol, carvedilol, metoprolol can lower your heart rate when taken together with pyridostigmine
  • Avoid alcohol consumption. Alcohol can enhance common side effects, including nausea and diarrhea.
Who Should Not Take Pyridostigmine
Contraindications associated with the use of pyridostigmine include:
  • If you have known blockage in your intestines. Pyridostigmine can increase the muscle contractions in the intestines, which can be dangerous when you have a blockage.
  • If you have known blockage in your urinary system. Pyridostigmine can increase the need to urinate, which can be dangerous if there is a blockage in your urine flow.
  • Those with an allergy to pyridostigmine and any of its ingredients should avoid taking pyridostigmine.
  • Your kidneys are responsible for removing pyridostigmine from your body. If you have kidney problems, pyridostigmine can build up in the body, increasing the risk of side effects.
  • Pyridostigmine can increase mucus production in the airways and can make breathing difficult, especially for those with asthma or other lung diseases.
  • Pyridostigmine interacts with many medications (see section above)
What If I Become Pregnant While Taking This Medication?
  • RTHM does not prescribe pyridostigmine for women who are pregnant or planning to become pregnant. If this medication is benefitting you, please have a discussion with your OB-GYN about the risks versus benefits of continuing this medication during your pregnancy.
  • If you become pregnant while taking this medication, pyridostigmine is FDA-rated as a pregnancy category C, meaning the potential risk cannot be ruled out. However, several studies show that pyridostigmine is safe during pregnancy when following recommended doses of 30-60 mg every 4-8 hours.
Medication Storage
  • Keep this medication in the container provided by the pharmacy. Ensure it is properly closed and out of the reach of children. Store at room temperature and away from excess heat, direct light, and moisture (not in the bathroom).
  • Do not share this medication with anyone else.
  • Do not throw away unwanted or expired medications. Do not flush down the toilet or pour down the drain. Ask your local pharmacist about local drug take back programs to discard your medication
Questions?
If you have questions about this medication, please contact us by using our support form. We generally respond within 2 business days. If you have a more urgent issue, please seek care from your local primary care provider, urgent care or emergency services.
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