• An ‘older’ but effective anticonvulsant.
  • It is most used in primary generalised epilepsies, particularly CAE.
  • There is now class 1 evidence for efficacy in CAE and it is regarded as the drug of choice.1


  • 1Tracy A. Glauser et al.Ethosuximide, Valproic Acid, and Lamotrigine in Childhood Absence Epilepsy. N Engl J Med 2010; 362:790-799

Side effects

Notable side effects

The main side effect is GI symptoms (abdominal pain). This is generally dose-dependent but can be intolerable and necessitate stopping the drug.

  • Hiccups
  • Rash
  • Joint pain
  • Drowsiness or lethargy
  • All anticonvulsants are potentially teratogenic and this is often dose related (see section: AED Prescribing - Pregnancy)

For a complete list of adverse effects, appropriate formularies should be consulted.


  • The initiation and escalation dose depends upon age, weight, syndrome, seizure frequency and severity, and side effect profile.
  • Unfortunately, one dose regime does not fit all.
  • A Paediatric Neurologist should be consulted if there is uncertainty.

Commonly used regime

  • Start 10-15mg/kg/day in two divided doses increasing weekly.
  • Around 20mg/kg/day is a reasonable target dose. Higher doses above 30mg/kg/day may be effective but GI symptoms are more frequent.
  • Dosages per kilogram can only be used in children of weight approximately up to 30-40kgs.
  • Maximum dosage in the older adolescent/adult range: 1500mg daily.
  • Consult appropriate formularies for children with higher weights and in the adult range.
  • These dosages are only a guide and appropriate formularies should be consulted as needed and tailored to the patient by the primary physician.

These dosages are only a guideline and appropriate formularies should be consulted as needed.


  • 250mg capsule or 50mg/ml syrup forms.


No routine blood tests are necessary.

Interactions | Precautions

  •  No significant drug interactions occur.