When You Can't Find Ethosuximide, What Are Your Options?

Ethosuximide is the gold standard for treating absence seizures. But if you can't find it at your pharmacy—or if supply issues are making it hard to get—you need to know what alternatives exist. This post covers the most commonly used alternatives to Ethosuximide, how they compare, and what to discuss with your doctor.

Important: Never switch or stop seizure medications on your own. Always talk to your neurologist before making any changes to your treatment plan.

What Is Ethosuximide and How Does It Work?

Ethosuximide (brand name: Zarontin) is a succinimide anticonvulsant that has been used since the 1960s. It is FDA-approved for absence seizures in patients aged 3 and older. It works by blocking T-type calcium channels in the thalamocortical neurons of the brain. These channels are responsible for the abnormal 3 Hz spike-and-wave electrical discharges that cause absence seizures—those brief episodes where a person stares blankly and becomes unresponsive for a few seconds.

Ethosuximide is highly effective for absence seizures specifically, but it does not treat other seizure types like generalized tonic-clonic seizures. For a deeper dive, read our post on how Ethosuximide works.

Alternative 1: Valproic Acid (Depakote, Depakene)

Valproic Acid is the most well-studied alternative to Ethosuximide for absence seizures. In clinical trials, Valproic Acid and Ethosuximide showed similar seizure freedom rates (58% vs. 53%), though Ethosuximide had fewer side effects overall.

Pros:

• Effective for absence seizures and generalized tonic-clonic seizures
• Widely available at most pharmacies
• Can be used if a patient has multiple seizure types
• Available as tablets, capsules, sprinkle capsules, and liquid

Cons:

• More side effects than Ethosuximide, including weight gain, hair loss, and tremor
• Significant risk of birth defects—not recommended for women of childbearing age unless other options have failed
• Requires regular blood monitoring for liver function and blood counts
• Can cause liver toxicity, especially in young children

Valproic Acid is often the first alternative neurologists consider if Ethosuximide isn't available or isn't working.

Alternative 2: Lamotrigine (Lamictal)

Lamotrigine is another option for absence seizures, though it is less effective than both Ethosuximide and Valproic Acid. In the same clinical trial mentioned above, Lamotrigine achieved seizure freedom in only about 21% of patients compared to 53% with Ethosuximide.

Pros:

• Generally well-tolerated with fewer side effects
• Preferred option for women of childbearing age due to better safety profile in pregnancy
• Also effective for other seizure types
• Widely available and affordable

Cons:

• Less effective for absence seizures than Ethosuximide or Valproic Acid
• Requires very slow dose titration (over several weeks) to reduce risk of serious skin reactions
• Small risk of Stevens-Johnson syndrome, a rare but serious skin condition

Lamotrigine may be a good choice if you need a medication with a milder side effect profile, especially if your absence seizures are infrequent.

Alternative 3: Clonazepam (Klonopin)

Clonazepam is a benzodiazepine that is sometimes used as an add-on therapy for absence seizures. It is not typically used as a first-line treatment.

Pros:

• Fast-acting—can help control seizures quickly
• Available in multiple dosage forms

Cons:

• Risk of tolerance—may become less effective over time
• Risk of physical dependence and withdrawal
• Sedation and cognitive side effects can be significant
• It is a Schedule IV controlled substance

Clonazepam is usually reserved for cases where other medications haven't worked or as a short-term bridge while waiting for another medication to become available.

Alternative 4: Clobazam (Onfi)

Clobazam is another benzodiazepine with evidence supporting its use in epilepsy with eyelid myoclonia and certain absence seizure syndromes. Like Clonazepam, it's typically used as an add-on rather than a standalone treatment.

Pros:

• Less sedating than Clonazepam
• Can be effective as adjunctive therapy

Cons:

• Still carries risk of tolerance and dependence
• Schedule IV controlled substance
• Limited evidence as monotherapy for absence seizures

How to Decide With Your Doctor

The right alternative depends on several factors:

• Your seizure type: If you only have absence seizures, Valproic Acid or Lamotrigine are the most common alternatives. If you also have generalized tonic-clonic seizures, Valproic Acid may be preferred.
• Your age and sex: Women of childbearing age should generally avoid Valproic Acid due to teratogenicity risks. Lamotrigine is often preferred in this group.
• Side effect concerns: If you're sensitive to side effects, Lamotrigine may be better tolerated than Valproic Acid.
• How quickly you need a switch: If this is a temporary supply issue, your doctor might recommend a short-term solution while you wait for Ethosuximide to become available.

For help finding Ethosuximide in stock before resorting to an alternative, try Medfinder or read our tips on how to find Ethosuximide in stock near you.

Final Thoughts

Ethosuximide remains the best option for most people with absence seizures, but it's reassuring to know that effective alternatives exist. Valproic Acid comes closest in efficacy, while Lamotrigine offers a gentler side effect profile. Benzodiazepines like Clonazepam and Clobazam can serve as short-term bridges.

Whatever you do, don't stop your seizure medication abruptly. Suddenly stopping Ethosuximide can trigger absence status epilepticus, a potentially dangerous condition. Work closely with your neurologist to make any transitions safely.

For more information about Ethosuximide, visit our comprehensive guide: What is Ethosuximide?