Prescription medication · Anticonvulsant (Barbiturate)

primidone

Name: primidone - FDA Drug Safety & Adverse Event Data
Creator: PlainMeds
License: https://creativecommons.org/publicdomain/zero/1.0/

Also sold as Mysoline. Primidone is used to manage grand mal, psychomotor, and focal epileptic seizures.

Compiled by PlainMeds, Drug Information Editorial Process

Data updated 2026-05-15

9,782
FDA reportsLightly reported: 9
InteractionsFew interactions: 98% less
Generic vs brandHuge savings: 6
Recall records

What the data shows

primidone (Mysoline) is a prescription Anticonvulsant (Barbiturate), reported less often than most tracked drugs (9,782 FDA reports), whose generic costs a fraction of the brand (about 98% less).

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

primidone (Mysoline) is a prescription Anticonvulsant (Barbiturate). Primidone is used to manage grand mal, psychomotor, and focal epileptic seizures.

Primidone is a medicine used to control seizures. It belongs to a class of drugs called anticonvulsants.

Verify with FDA → · CMS NADAC pricing →

Drug Pricing (NADAC)

Brand Price

$62.56/unit

Generic Price

$1.25/unit

Generic Savings

98%

Generic Available

Yes (7 manufacturers)

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

View Alternatives → Compare with Another Drug → Full Side Effects Report →

What it does

Primidone is used to manage grand mal, psychomotor, and focal epileptic seizures.

Common side effects

Feeling unsteady, Dizziness, Drowsiness

Key warnings

You should not take primidone if you have porphyria or are allergic to phenobarbital.

The sections below are summarized in plain English from primidone's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Primidone works in the brain to reduce the frequency of seizures. It is similar to a barbiturate and helps to stabilize electrical activity. This can help prevent seizures from starting.

Side Effects (from patient reports)

Based on 9,782 FDA adverse event reports.

Fall

651
Fatigue

616
Tremor

568
Dizziness

484
Diarrhoea

480
Nausea

458
Headache

385
Drug Interaction

378
Somnolence

377
Asthenia

353

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Reports over time

Adverse-event reports filed for primidone each year to the FDA Adverse Event Reporting System (FAERS).

Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.

Where primidone sits

primidone has more FDA adverse-event reports than 39% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.

fewest reports most reports

Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is primidone; the line is the median (50th percentile).

FDA Adverse Event Report Analysis

Detailed analysis of 9,782 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2002–2025.

Total Reports

9,782

Reports Mentioning Death

850

8.7% of reports — not proof of cause

Hospitalization Reports

3,062

Top Indication

Product Used For Unknown Indication

Gender Distribution

Female 5,513 (60%)

Male 3,635 (40%)

Age Distribution

0–17 212

18–44 635

45–64 1,922

65–74 1,784

75+ 1,637

Most Reported Adverse Reactions (FAERS)

#	Reaction	Reports
2	FALL	651
3	FATIGUE	616
4	TREMOR	568
5	DIZZINESS	484
6	DIARRHOEA	480
8	NAUSEA	458
9	HEADACHE	385
10	DRUG INTERACTION	378
11	SOMNOLENCE	377
12	ASTHENIA	353
13	DYSPNOEA	349
14	WEIGHT DECREASED	321
15	PAIN	319
16	PNEUMONIA	297
17	DEATH	290

Reactions in Death Reports

DEATH 289

COMPLETED SUICIDE 162

TOXICITY TO VARIOUS AGENTS 60

CARDIAC ARREST 35

PNEUMONIA 35

RENAL FAILURE 33

FALL 30

DYSPNOEA 29

CARDIO-RESPIRATORY ARREST 28

ASTHENIA 24

Reactions in Hospitalization Reports

FALL 376

PNEUMONIA 249

TREMOR 191

DIARRHOEA 186

ASTHENIA 173

DYSPNOEA 171

NAUSEA 169

DRUG INTERACTION 166

FATIGUE 157

WEIGHT DECREASED 147

Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation

Serious Warnings

You should not take primidone if you have porphyria or are allergic to phenobarbital.

Known Drug Interactions

major nirmatrelvir/ritonavir

Anticonvulsants carbamazepine , phenobarbital, primidone, phenytoin ↓ nirmatrelvir/ritonavir Co-administration contraindicated due to potential loss of virologic response and possible resistance [see Contraindications (4) ] .

Mechanism: Primidone makes your body break down nirmatrelvir/ritonavir too fast, which lowers the amount of medicine in your blood. This can make the treatment stop working and help the virus become harder to treat.

minor carbamazepine

Drugs that have been shown, or that would be expected, to decrease plasma carbamazepine levels include cisplatin, doxorubicin HCl, felbamate, fosphenytoin, rifampin, phenobarbital, phenytoin, primidone, methsuximide, theophylline, aminophylline.

Mechanism: Primidone speeds up the liver's ability to break down carbamazepine, which lowers the amount of medicine in your blood.

minor drospirenone/ethinyl estradiol

7.5 Effects of Other Drugs on Folates Several drugs have been reported to reduce folate concentrations by inhibition of the dihydrofolate reductase enzyme (e.g., methotrexate and sulfasalazine) or by reducing folate absorption (e.g., cholestyramine), or via unknown mechanisms (e.g., antiepileptics such as carbamazepine, phenytoin, phenobarbital, primidone and valproic acid).

Mechanism: Primidone can lower the amount of folate (a B-vitamin) in your body through a process that is not yet fully understood.

minor lamotrigine

Phenobarbital/Primidone ↓ lamotrigine Decreased lamotrigine concentration approximately 40%. ( 7 , 12.3 ) Carbamazepine, phenytoin, phenobarbital, primidone, and rifampin decrease lamotrigine concentrations by approximately 40%.

Mechanism: Primidone speeds up how fast your body breaks down lamotrigine, which lowers the amount of medicine in your blood.

minor prenatal multivitamin

Drugs which may interact with folate include: • Antiepileptic drugs (AED): The AED class including, but not limited to, phenytoin, carbamazepine, primidone, valproic acid, fosphenytoin, valproate, phenobarbital and lamotrigine have been shown to impair folate absorption and increase the metabolism of circulating folate.

Mechanism: Primidone interferes with how your body absorbs folate and speeds up how fast your body uses up the folate in your system.

Check all your medications →

This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

Common Questions

Can I stop taking primidone suddenly?

No, do not stop taking primidone suddenly. Talk to your doctor first, as stopping suddenly can cause seizures.

Will primidone interact with other medications I'm taking?

Yes, primidone can interact with other medications. Tell your doctor about all the medicines you take, including over-the-counter drugs and supplements.

Can I drink alcohol while taking primidone?

It is best to avoid alcohol while taking primidone, as it can increase drowsiness and other side effects.

How long does it take for primidone to start working?

It may take several days or weeks for primidone to reach a steady level in your body and for you to see its full effects.

What should I do if I experience side effects?

If you experience side effects, talk to your doctor. They may be able to adjust your dose or recommend other ways to manage the side effects.

Can children take primidone?

Yes, children can take primidone. The dosage will be different than for adults. Follow your doctor's instructions carefully.

Will primidone make me feel tired?

Yes, drowsiness is a common side effect of primidone. Be careful when driving or operating machinery.

Does primidone cure epilepsy?

No, primidone does not cure epilepsy. It helps to control seizures, but it is not a cure.

Can I take primidone if I have kidney problems?

Talk to your doctor if you have kidney problems before taking primidone. Your doctor may need to adjust your dose.

Is it safe to drive while taking primidone?

Primidone can cause drowsiness and dizziness. Talk to your doctor about whether it is safe for you to drive while taking this medicine.

What are the common side effects of primidone?

The registry lists Feeling unsteady, Dizziness, Drowsiness among the most-reported FAERS reaction terms for primidone. The compiled record contains 9,782 FDA adverse-event reports. These counts are not an individual symptom assessment.

Does primidone interact with other medications?

The registry has 9 documented interaction rows for primidone. Notable source-record pairings include nirmatrelvir/ritonavir, carbamazepine, drospirenone/ethinyl estradiol. These rows are not a complete medication review.

What drug class is primidone?

primidone belongs to the Anticonvulsant (Barbiturate) drug class. It requires a prescription (Rx). Primidone is used to manage grand mal, psychomotor, and focal epileptic seizures.

Is there a generic version of primidone?

Yes, generic primidone is available from 7 manufacturers. The generic costs $1.25 per unit compared to $62.56 for the brand version, saving approximately 98%. Pricing is based on NADAC (National Average Drug Acquisition Cost) data from CMS.

What pregnancy or breastfeeding source fields are listed for primidone?

The FDA label for primidone contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.

Has primidone been recalled?

There are 6 recalls associated with primidone products. Cross Contamination with Other Products: due to a potential for cross-contamination with Acemetacin API due to an issue at the API manufacturer. Check the recalls section below for full details and affected products.

Active Recalls

Class III June 3, 2026

Cross Contamination with Other Products: due to a potential for cross-contamination with Acemetacin API due to an issue at the API manufacturer.

Amneal Pharmaceuticals, LLC

Class III May 1, 2026