Background: Medication reconciliation is a pharmaceutical care practice to prevent drug-related problems during pharmacotherapy. Case: A 16-year-old woman with a 4-year history of epilepsy was admitted to the emergency care unit following two recent seizures episodes with acute headache. The patient was treated with lamotrigine 25 mg plus carbamazepine 200 mg twice daily but is now breastfeeding at 22 days postpartum. A single dose of diazepam 10 mg plus phenobarbital 100 mg once daily were added in order to control seizures. The changes in the response to treatment may reflect changes in pharmacokinetics or presence of drug interaction during pregnancy. It is also well known that phenobarbital can induce drug metabolism and accelerate drug elimination. Conclusion: In such cases, medication reconciliation is essential in order to optimise response to medication and to prevent drug-related problems.