Comprehensive medication guide to Ethosuximide including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
With insurance, Ethosuximide is usually covered as a preferred generic with typical copays of $5 to $30 per month.
Estimated Cash Pricing
Ethosuximide typically costs $200 to $580 for a 30-day supply without insurance, but coupon cards can bring it down to as low as $32.
Medfinder Findability Score
55/100
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Ethosuximide is a succinimide anticonvulsant medication FDA-approved for the treatment of absence seizures (petit mal) in patients aged 3 and older. It is considered a first-line treatment for absence seizures and has been used for decades. Ethosuximide is available as both a generic and under the brand name Zarontin, manufactured by Pfizer. It is taken orally as a capsule or liquid solution, typically once or twice daily.
Ethosuximide works by blocking T-type voltage-gated calcium channels in thalamocortical neurons in the brain. These channels are responsible for generating the low-threshold calcium currents that produce the characteristic 3 Hz spike-and-wave discharges seen in absence seizures. By suppressing these abnormal electrical signals, Ethosuximide prevents the brief lapses in consciousness that define absence seizures.
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250 mg capsules
available in generic form
250 mg/5 mL oral solution (syrup) — solution
available as brand Zarontin and generic
Ethosuximide scores a 55 out of 100 on our findability scale, meaning it can be moderately difficult to locate in stock. Because it treats a relatively uncommon condition (absence seizures), many pharmacies don't keep it on their shelves. While there is no active FDA-listed shortage, spot shortages at individual pharmacies are common due to low demand and a limited number of manufacturers. If your local pharmacy doesn't have it, you may need to call around or use Medfinder to locate a pharmacy that has Ethosuximide available.
Ethosuximide is most commonly prescribed by:
Telehealth consultations are also available for Ethosuximide prescriptions in many states.
No, Ethosuximide is not a controlled substance. It is not classified under any DEA schedule. This means there are no special prescribing restrictions, refill limits, or ID requirements beyond a standard prescription. Pharmacies can transfer prescriptions between locations and refills can be called in by your doctor.
Most gastrointestinal side effects improve by taking Ethosuximide with food. Serious but rare side effects include Stevens-Johnson syndrome, blood disorders (agranulocytosis, aplastic anemia), and suicidal thoughts. Contact your doctor immediately if you develop a rash, unusual bleeding, or mood changes.
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Valproic Acid (Depakote/Depakene)
a first-line alternative for absence seizures with similar efficacy. Also treats generalized tonic-clonic seizures. Has more side effects including weight gain and is highly teratogenic.
Lamotrigine (Lamictal)
a second-line option for absence seizures. Less effective than Ethosuximide but better tolerated overall. Often preferred in women of childbearing age.
Clonazepam (Klonopin)
a benzodiazepine sometimes used adjunctively for absence seizures. Risk of tolerance and dependence limits long-term use.
Clobazam (Onfi)
a benzodiazepine with some evidence for absence seizures. Typically used as add-on therapy.
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Phenytoin, Carbamazepine, Phenobarbital
moderatethese enzyme inducers can reduce Ethosuximide levels, potentially decreasing seizure control
Isoniazid
moderatemay slow Ethosuximide metabolism and increase blood levels
Valproic Acid
moderatevariable effects on Ethosuximide levels; monitor closely when used together
Rifampicin
moderateincreases clearance of Ethosuximide
CNS Depressants
moderate(opioids, benzodiazepines, alcohol) — additive sedation when combined with Ethosuximide
Lamotrigine
moderateEthosuximide may reduce Lamotrigine levels by up to 37% in children
Ethosuximide remains one of the most effective and well-established treatments for absence seizures, with decades of clinical use supporting its safety and efficacy. While it can be moderately difficult to find in stock at some pharmacies due to low demand and limited manufacturers, it is not currently in a formal shortage. Generic versions are available at significant savings with coupon cards — as low as $32 per month. If you're having trouble finding Ethosuximide at your local pharmacy, use Medfinder to search for nearby pharmacies that have it available. Never stop taking Ethosuximide abruptly, as this can trigger absence status epilepticus.
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