Which Second-Line Treatments for Childhood Absence Epilepsy?

It can be incredibly disheartening to watch your child continue to have absence seizures after starting their first medication. As a parent, you might worry that this means the epilepsy is unusually severe. However, failing the first medication is a common part of the process. In major clinical studies, 20% to 30% of children (and in some trials, over half) do not become completely seizure-free on their first medication ^[1][2]. Sometimes the medication doesn’t fully stop the seizures ^[3], and sometimes it causes side effects that make it hard to tolerate; in one large study, 25% of children had to stop taking ethosuximide due to side effects ^[2]. If ethosuximide isn’t the right fit, there are proven second-line options.

What to Do Before Switching Medications

Before changing drugs, your pediatric neurologist will likely want to take a few steps to understand why the first treatment didn’t work:

• Verify the spells: The doctor may recommend a repeat EEG (a brain-wave test, potentially with hyperventilation) to confirm that the staring spells are actually absence seizures, rather than medication side effects or typical childhood daydreaming. Keeping a seizure diary and taking video of the spells can be very helpful.
• Check adherence and dose: Children grow quickly. The doctor will check if the dose needs to be adjusted for your child’s current weight, and whether any doses are being missed or vomited. Routine blood levels are not always required or helpful for every drug; clinical response is often more important.
• Review for other seizure types: It is crucial to check if your child has developed other types of seizures, such as generalized tonic-clonic seizures (whole-body stiffening and shaking with loss of awareness). Ethosuximide treats absence seizures but does not protect against convulsive seizures, which would require a different medication ^[3].

Important Transition Safety: Never stop ethosuximide abruptly or change the dose without your doctor’s instructions. A sudden stop can trigger more severe seizures. Switching medications requires a carefully planned cross-taper, where the new drug is slowly introduced while the old one is gradually reduced.

Second-Line Monotherapy Options

When the first drug fails, guidelines suggest trying a different single medication (called monotherapy) ^[4]. For childhood absence epilepsy, the standard alternatives are valproic acid and lamotrigine.

Doctors often measure success using a term called “freedom from treatment failure.” This means the drug completely stopped the seizures and the child was able to tolerate the side effects without having to stop the medication.

Valproic Acid

Valproic acid is highly effective for stopping absence seizures. For children who tried it after their first medication failed, about 49% achieved freedom from treatment failure at 12 months ^[5].

• Common Side Effects: Weight gain, tremor, gastrointestinal issues, and hair thinning. It is also more likely than lamotrigine or ethosuximide to cause issues with attention, behavior, and hyperactivity ^[6][5].
• Serious Warnings: Rarely, valproic acid can cause severe liver injury, pancreatitis, or low blood platelets. Seek urgent medical care for persistent vomiting, severe abdominal pain, unusual bruising, jaundice (yellowing of skin or eyes), or extreme lethargy.
• Reproductive Safety: Taking valproic acid during a future pregnancy carries high risks for major birth defects and neurodevelopmental issues in the baby. For anyone who could become pregnant, medical guidelines strongly recommend avoiding valproic acid if there are safer alternatives ^[7]. This requires age-appropriate counseling, though taking it now as a child does not permanently affect future fertility or pregnancies once the drug is safely stopped.

Lamotrigine

While lamotrigine is generally less effective at completely stopping absence seizures than valproic acid—with about 36% of children experiencing freedom from treatment failure at 12 months in the same second-line trial ^[5]—it is often chosen because it typically causes fewer behavioral and attention problems ^[2][6].

• Serious Warning (Severe Rash): Lamotrigine can cause a rare but life-threatening skin reaction (Stevens-Johnson syndrome). The medication must be increased very slowly over many weeks. Seek immediate emergency care if your child develops a new rash, especially if accompanied by fever, facial swelling, skin peeling, blisters, or sores in the mouth or eyes.

Medication Comparison

Combination Therapy

If two different single medications have been tried at adequate doses without success, your neurologist may consider a referral to a specialized epilepsy center and might suggest combination therapy (using two medications at once) ^[8][9].

There is limited high-quality evidence for specific combinations, but small observational studies suggest that combining valproate with lamotrigine ^[10], or valproate with ethosuximide ^[11], can be beneficial for refractory (hard-to-treat) absence seizures. However, combining medicines can increase side effects and drug interactions. For example, taking valproate increases the levels of lamotrigine in the blood, which significantly raises the risk of the severe lamotrigine rash. This combination requires highly specialized, cautious dosing.

While the journey can be stressful, many children with childhood absence epilepsy do eventually find a medication or combination that controls their seizures. For the minority who do not, specialized pediatric epilepsy centers can provide advanced care and evaluation.