Epilepsy is a serious health disorder affecting both paediatric and adult population worldwide. Due to difficulties in identifying its aetiology, initial management is often guided by empiric therapy measures. Symptomatic control requires the use of antiepileptic drugs (AEDs), many of which have the potential for adverse drug interactions. Children are especially susceptible to drug interactions and frequently exhibit atypical adverse events, which may require special care. Aim. To demonstrate a case of a 15 year old girl suffering from refractory epilepsy with underlying focal cortical dysplasia (FCD), whose seizure deterioration was most probably associated with drug-drug interactions between prescribed common antiepileptic drugs, namely valproic acid, phenobarbital or the prodrug primidon and carbamazepine.