What the label lists and what reports show
Primidone side effects
Primidone's FDA label lists its adverse reactions in its own words. FAERS holds 10,126 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 fall (670 reports).
- Generic listed
Check it at the source: the primidone FDA label on DailyMed (effective September 10, 2026, Bausch Health US, LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of MYSOLINE?See “What is the most important information I should know about MYSOLINE?” MYSOLINE may cause other serious side effects including: • Sleepiness that can be severe, especially when you first start taking MYSOLINE. • MYSOLINE may rarely cause blood problems. Symptoms may include: o fever, swollen glands, or sore throat that come and go or do not go away o frequent infections or an infection that does not go away o tiredness o shortness of breath • MYSOLINE may rarely cause allergic reactions. Symptoms may include: o skin rash o hives o sores in your mouth o blistering or peeling skin The most common side effects of MYSOLINE include: • problems with walking and moving • feelings of dizziness, spinning, or swaying (vertigo) These are not all the possible side effects of MYSOLINE. For more information, ask your healthcare provider or pharmacist. […]
Source: FDA drug label, NDA009170 (Valeant), as published by Bausch Health US, LLC, effective September 10, 2026 (SPL set af593171-dabb-4ea3-b44c-89ed457b2c46), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most frequently occurring early side effects are ataxia and vertigo. These tend to disappear with continued therapy, or with reduction of initial dosage. Occasionally, the following have been reported: nausea, anorexia, vomiting, fatigue, hyperirritability, emotional disturbances, sexual impotency, diplopia, nystagmus, drowsiness, and morbilliform skin eruptions. Granulocytopenia, agranulocytosis, and red-cell hypoplasia and aplasia, have been reported rarely. These and, occasionally, other persistent or severe side effects may necessitate withdrawal of the drug. Megaloblastic anemia may occur as a rare idiosyncrasy to MYSOLINE and to other anticonvulsants. The anemia responds to folic acid without necessity of discontinuing 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.
Source: FDA drug label, NDA009170 (Valeant), as published by Bausch Health US, LLC, effective September 10, 2026 (SPL set af593171-dabb-4ea3-b44c-89ed457b2c46), via openFDA; the full label on DailyMed
What do FAERS reports show?
10,126 reports list primidone among the medicines taken, each a report of something that happened, not proof the medicine caused it; 874 are coded as a death and 3,162 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, 4 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?
- Primidone: 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