What the label lists and what reports show
Pyridostigmine side effects
Pyridostigmine's FDA label lists its adverse reactions in its own words. FAERS holds 10,653 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (915 reports).
- Generic listed
Check it at the source: the pyridostigmine FDA label on DailyMed (effective December 2, 2020, Bausch Health US, LLC); the FDA FAERS public dashboard.
What does the label list?
From the label: adverse reactionsThe side effects of MESTINON 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. To report SUSPECTED ADVERSE REACTIONS, contact Bausch Health US, LLC at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Table 1: Incidence of Adverse Reactions ≥ 2%
This table is printed in the Pyridostigmine Bromide label published by Surgeon General-Department of the Army (TSG-DA) of December 23, 2025; the label quoted above does not print one.
| Adverse Reaction | Pyridostigmine N = 60 % | Placebo N = 30 % |
|---|---|---|
| Diarrhea | 7 | 0 |
| Abdominal pain | 7 | 0 |
| Dysmenorrhea | 5 | 0 |
| Twitch | 3 | 0 |
| Myalgia | 2 | 0 |
| Dry skin | 2 | 0 |
| Urinary frequency | 2 | 0 |
| Epistaxis | 2 | 0 |
| Amblyopia | 2 | 0 |
| Hypesthesia | 2 | 0 |
| Neck pain | 2 | 0 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
Source: FDA drug label, Bausch Health US, LLC, effective December 2, 2020 (SPL set a851795e-b7a8-40c3-9922-5e79d3eb4d92), via openFDA; the full label on DailyMed
What do FAERS reports show?
10,653 reports list pyridostigmine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 806 are coded as a death and 3,764 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 5 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Pyridostigmine: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions