What does Mysoline treat?

Mysoline (Primidone) may be used to treat partial epilepsies, tonic-clonic epilepsy, tremor, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.

How does Mysoline work?

Mysoline is a anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably.

How is Mysoline rated?

pharmaranks gives Mysoline a composite score of 3.5 out of 5, currently based on 1 weighted source (FDA regulatory recall-safety data weighted highest). See our methodology at /how-we-rate.

How much does Mysoline cost?

Nobody can tell you what you will pay — your price is set by your insurer's formulary, your deductible and the pharmacy's markup, and none of those are published. What IS published is what the pharmacy paid to acquire it: about $2.89 for 30, per the CMS NADAC survey. Treat that as the floor, not the quote — ask the pharmacist for the cash price as well as your copay, because for cheap generics the cash price often wins.

Is there a coupon or discount for Mysoline?

pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Mysoline. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.

Mysoline is marketed by Valeant Pharm Intl. You can see Valeant Pharm Intl's full profile, rating, and other products on pharmaranks.

Is Mysoline a brand-name or generic drug?

Mysoline is a brand-name product with the active ingredient Primidone. Lower-cost generic equivalents containing Primidone are available — ask your pharmacist.

Is Mysoline available over the counter?

No. Mysoline is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.

What forms does Mysoline come in?

Mysoline is currently marketed as tablet, per the FDA's National Drug Code Directory.

What class of drug is Mysoline?

Mysoline is classified as anti-epileptic agent, per the FDA's Established Pharmacologic Class.

Is Mysoline FDA-registered?

Mysoline is on record with the U.S. FDA under application number NDA009170. You can verify this on its official FDA label.

Has Mysoline been recalled by the FDA?

Mysoline has no FDA recalls recorded under its own application in the openFDA enforcement database. Its recall-safety score reflects its manufacturer's overall recall record. This is general reference, not medical advice — check the FDA recall database for the latest alerts.

There's no single safe-or-not verdict. pharmaranks gives Mysoline a recall-safety score of 70/100, based on its FDA recall history (no recalls under its own FDA application) — not an efficacy or side-effect rating. Review its FDA-label side effects and warnings before use, and always consult a licensed professional.

#5 of 19 in Anti-epileptic Agent

mysoline

Pharmaranks rates Mysoline 3.5/5 for recall safety — an independent score from its FDA recall history and its manufacturer's record. Mysoline (Primidone) is an anti-epileptic agent used to treat Partial Epilepsies, Tonic-Clonic Epilepsy, Tremor.

Primidone · by Valeant Pharm Intl

Available as a generic: Primidone

70/100Limited · 1 source

Based on 1 source · Recall-safety score from FDA recall history — this product's own recalls and its manufacturer's record. Not an efficacy or quality rating. methodology →

Rated against independent regulatory sources·Last updated August 22, 2026·How we rate

Verified againstopenFDANIH DailyMedRxClass

~$2.89 /30

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Key facts

Active ingredient: Primidone
Drug class: Anti-Epileptic Agent
Form: Tablet
Strength: Primidone 250MG · Primidone 50MG
Type: Prescription (Rx)
Brand or generic: Brand-name
May treat: partial epilepsies, tonic-clonic epilepsy, tremor
Manufacturer: Valeant Pharm Intl
What the pharmacy pays: ~$2.89 for 30 — not your price
FDA application: NDA009170

What is Mysoline?

From the FDA label:Chemical name: 5-ethyldihydro-5-phenyl-4,6 (1H, 5H)-pyrimidinedione. Structural formula: MYSOLINE (primidone) is a white, crystalline, highly stable substance, M.P. 279-284°C. It is poorly soluble in water (60 mg per 100 mL at 37°C) and in most organic solvents. It possesses no acidic properties, in contrast to its barbiturate analog. MYSOLINE 50 mg and 250 mg tablets contain the following inactive ingredients: lactose monohydrate, NF; magnesium stearate, NF; methylcellulose, USP; microcrystalline cellulose, NF; purified water, USP; sodium lauryl sulfate, NF; sodium starch glycolate, NF; and talc, USP. MYSOLINE 250 mg tablets also contain ferric oxide yellow, NF. _______________________________________________________________________________ ACTIONS MYSOLINE raises electro- or chemoshock seizure thresholds or alters seizure patterns in experimental animals. The mechanism(s) of primidone’s antiepileptic action is not known. Primidone per se has anticonvulsant activity as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). In addition to its anticonvulsant activity, PEMA potentiates the anticonvulsant activity of phenobarbital in experimental animals. Chemical Structure

How to use

Usual Dosage Patients 8 years of age and older who have received no previous treatment may be started on MYSOLINE according to the following regimen using either 50 mg or scored 250 mg MYSOLINE tablets: Days 1 to 3: 100 to 125 mg at bedtime. Days 4 to 6: 100 to 125 mg twice a day. Days 7 to 9: 100 to 125 mg three times a day. Day 10 to maintenance: 250 mg three times a day. For most adults and children 8 years of age and over, the usual maintenance dosage is three to four 250 mg MYSOLINE tablets in divided doses (250 mg three times a day or four times a day). If required, an increase to five or six 250 mg tablets daily may be made, but daily doses should not exceed 500 mg four times a day. Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations of primidone may be necessary for optimal dosage adjustment. The clinically effective serum level for primidone is between 5 to 12 mcg/mL. INITIAL: ADULTS AND CHILDREN OVER 8 KEY: •=50 mg tablet; ●=250 mg tablet DAY 1 2 3 4 5 6 AM •• •• •• NOON PM •• •• •• •• •• •• DAY 7 8 9 10 11 12 AM •• •• •• ● Adjust to Maintenance NOON •• •• •• ● PM •• •• •• ● Patients Already Receiving Other Anticonvulsants MYSOLINE should be started at 100 to 125 mg at bedtime and gradually increased to maintenance level as the other drug is gradually decreased. This regimen should be continued until…

Side effects

The 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.

Warnings

Important safety information

The abrupt withdrawal of antiepileptic medication may precipitate status epilepticus. The therapeutic efficacy of a dosage regimen takes several weeks before it can be assessed. Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including MYSOLINE, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication. Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% Cl:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated. There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide. The increased risk of suicidal thoughts or behavior with AEDs was observed as early as 1 week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed. The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5 to 100 years) in the clinical trials analyzed. Table 1 shows absolute and relative risk by indication for all evaluated AEDs. Table 1: Risk by indication for antiepileptic drugs in the pooled analysis Indication Placebo Patients with Events Per 1000 Patients Drug Patients with Events Per 1000 Patients Relative Risk: Incidence of Events in Drug Patients/ Incidence in Placebo Patients Risk Difference: Additional Drug Patients with Events Per 1000 Patients Epilepsy 1.0 3.4 3.5 2.4 Psychiatric 5.7 8.5 1.5 2.9 Other 1.0 1.8 1.9 0.9 Total 2.4 4.3 1.8 1.9 The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications. Anyone considering prescribing MYSOLINE or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness. Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated. Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers. Pregnancy To provide information regarding the effects of in utero exposure to MYSOLINE, physicians are advised to recommend that pregnant patients taking MYSOLINE enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/. The effects of MYSOLINE in human pregnancy and nursing infants are unknown. Recent reports suggest an association between the use of anticonvulsant drugs by women with epilepsy and an elevated incidence of birth defects in children born to these women. Data are more extensive with respect to diphenylhydantoin and phenobarbital, but these are also the most commonly prescribed anticonvulsants; less systematic or anecdotal reports suggest a possible similar association with the use of all known anticonvulsant drugs. The reports suggesting an elevated incidence of birth defects in children of drug-treated epileptic women cannot be regarded as adequate to prove a definite cause-and-effect relationship. There are intrinsic methodologic problems in obtaining adequate data on drug teratogenicity in humans; the possibility also exists that other factors leading to birth defects, e.g., genetic factors or the epileptic condition itself, may be more important than drug therapy. The great majority of mothers on anticonvulsant medication deliver normal infants. It is important to note that anticonvulsant drugs should not be discontinued in patients in whom the drug is administered to prevent major seizures because of the strong possibility of precipitating status epilepticus with attendant hypoxia and threat to life. In individual cases where the severity and frequency of the seizure disorders are such that the removal of medication does not pose a serious threat to the patient, discontinuation of the drug may be considered prior to and during pregnancy, although it cannot be said with any confidence that even minor seizures do not pose some hazard to the developing embryo or fetus. The prescribing physician will wish to weigh these considerations in treating or counseling epileptic women of childbearing potential. Neonatal hemorrhage, with a coagulation defect resembling vitamin K deficiency, has been described in newborns whose mothers were taking primidone and other anticonvulsants. Pregnant women under anticonvulsant therapy should receive prophylactic vitamin K1 therapy for 1 month prior to, and during, delivery.

Who should not take Mysoline

Primidone is contraindicated in: 1) patients with porphyria and 2) patients who are hypersensitive to phenobarbital (see ACTIONS ).

Drug class

Anti-epileptic Agent

How this class works, per Seizure Medications — StatPearls, NCBI Bookshelf (NIH).

May treat (source: NIH RxClass)

See how Mysoline ranks — best-rated anti-epileptic agent for:

Dosage forms

Tablet

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

Ways to save

Ask for the generic

Same active ingredient, far cheaper. Is there a generic? →

Request a 90-day supply

Bulk fills usually lower the per-dose price vs monthly refills.

Use copay cards

Manufacturer copay cards & patient-assistance programs — especially for brand drugs.

Compare alternatives

A same-class option may cost less. See alternatives →

Frequently asked questions

What does Mysoline treat?: Mysoline (Primidone) may be used to treat partial epilepsies, tonic-clonic epilepsy, tremor, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
How does Mysoline work?: Mysoline is a anti-epileptic agent. Anti-epileptic (anticonvulsant) drugs calm the abnormal, excessive electrical activity that triggers seizures. They do this by stabilizing overactive sodium or calcium channels in nerve cells, boosting the brain's natural calming chemical GABA, or dampening excitatory signals, which makes nerves less likely to fire uncontrollably.
How is Mysoline rated?: pharmaranks gives Mysoline a composite score of 3.5 out of 5, currently based on 1 weighted source (FDA regulatory recall-safety data weighted highest). See our methodology at /how-we-rate.
How much does Mysoline cost?: Nobody can tell you what you will pay — your price is set by your insurer's formulary, your deductible and the pharmacy's markup, and none of those are published. What IS published is what the pharmacy paid to acquire it: about $2.89 for 30, per the CMS NADAC survey. Treat that as the floor, not the quote — ask the pharmacist for the cash price as well as your copay, because for cheap generics the cash price often wins.
Is there a coupon or discount for Mysoline?: pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Mysoline. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Mysoline?: Mysoline is marketed by Valeant Pharm Intl. You can see Valeant Pharm Intl's full profile, rating, and other products on pharmaranks.
Is Mysoline a brand-name or generic drug?: Mysoline is a brand-name product with the active ingredient Primidone. Lower-cost generic equivalents containing Primidone are available — ask your pharmacist.
Is Mysoline available over the counter?: No. Mysoline is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Mysoline come in?: Mysoline is currently marketed as tablet, per the FDA's National Drug Code Directory.
What class of drug is Mysoline?: Mysoline is classified as anti-epileptic agent, per the FDA's Established Pharmacologic Class.
Is Mysoline FDA-registered?: Mysoline is on record with the U.S. FDA under application number NDA009170. You can verify this on its official FDA label.
Has Mysoline been recalled by the FDA?: Mysoline has no FDA recalls recorded under its own application in the openFDA enforcement database. Its recall-safety score reflects its manufacturer's overall recall record. This is general reference, not medical advice — check the FDA recall database for the latest alerts.
Is Mysoline safe?: There's no single safe-or-not verdict. pharmaranks gives Mysoline a recall-safety score of 70/100, based on its FDA recall history (no recalls under its own FDA application) — not an efficacy or side-effect rating. Review its FDA-label side effects and warnings before use, and always consult a licensed professional.
What are the side effects of Mysoline?: Mysoline's side effects are taken directly from its FDA label. From the label: The 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,… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.