Side Effects of Mestinon (pyridostigmine)

Mestinon (pyridostigmine) is an oral cholinesterase inhibitor used to treat myasthenia gravis. 

Acetylcholine is a neurotransmitter, a chemical that helps cells communicate with each other. One important function of acetylcholine is to produce muscle contractions and movement. In people with myasthenia gravis or people treated with neuromuscular blocking medicines there is a decrease in acetylcholine levels.

Mestinon may be used to increase acetylcholine levels and improve muscle contraction or movement. Mestinon increases the concentration of acetylcholine at nerve junctions by inhibiting cholinesterase, the enzyme that destroys acetylcholine.

Common side effects of Mestinon include

• nausea,
• vomiting,
• diarrhea,
• stomach cramps,
• increased salivation,
• increased bronchial secretions,
• pupil constriction, and
• sweating.

Serious side effects of Mestinon include

• new or increased muscle cramps/weakness/twitching,
• shortness of breath,
• new or increased difficulty swallowing,
• slow heartbeat, dizziness, and
• headache.

Drug interactions of Mestinon include other cholinesterase inhibitors such as neostigmine or edrophonium because of the risk of additive toxicity.

Use of quinine with Mestinon should be avoided as the actions of quinine on skeletal muscle are opposite to those of Mestinon.

The safety of Mestinon during pregnancy has not been evaluated. Mestinon should only be used during pregnancy if the benefits of treatment outweigh the potential risk to the mother and the unborn baby.

Mestinon can be excreted into human milk. The American Academy of Pediatrics considers Mestinon to be generally compatible with nursing. Mestinon should be used cautiously in breastfeeding mothers.

Possible side effects of pyridostigmine therapy include:

• nausea,
• vomiting,
• diarrhea,
• stomach cramps,
• the digestion process (creased peristalsis)
• increased salivation,
• increased bronchial secretions,
• pupil constriction (miosis),
• sweating,
• muscle cramps,
• muscle twitching, and
• weakness.

The side effects of Mestinon (pyridostigmine) are most commonly related to overdosage and generally are of two varieties, muscarinic and nicotinic. Among those in the former group are

• nausea,
• vomiting,
• diarrhea,
• abdominal cramps,
• increased peristalsis,
• increased salivation,
• increased bronchial secretions,
• miosis and
• diaphoresis.

Nicotinic side effects are comprised chiefly of

• muscle cramps,
• fasciculation and
• weakness.

Muscarinic side effects can usually be counteracted by atropine, but for reasons shown in the preceding section the expedient is not without danger.

As with any compound containing the bromide radical, a skin rash may be seen in an occasional patient. Such reactions usually subside promptly upon discontinuance of the medication.

No information provided.