Objective To describe the dispensing of the hypnotic alimemazine to children aged 0–3 years and investigate the association between dispensing of alimemazine to children and dispensed hypnotics to their parents.

Design An observational cohort study linking information from the Medical Birth Registry of Norway and the Norwegian Prescription Database. Hypnotics dispensed to parents in a 1-year period before pregnancy was associated with dispensed alimemazine for children aged 0–3 years.

Patients and setting All children born in Norway in 2008 (N=59 325) and their mothers and fathers were included.

Main outcome measures Dispensed alimemazine to children during the first 3 years of life.

Results Three percent of children received alimemazine. Dispensed hypnotics to mothers increased the risk of the child receiving a prescription for alimemazine, OR of 2.3 (1.7–3.0) for boys and 1.7 (1.2–2.4) for girls. When both parents had been dispensed prescriptions for hypnotics, the risk increased nearly threefold. A dispensed alimemazine prescription was also associated with dispensed prescriptions for antidepressants to both mother and father, mother's smoking, the child's gender and child's prescriptions for antibiotics, respiratory drugs and dermatological steroids.

Conclusions Dispensed alimemazine to children under 3 was associated with parents’ previous use of hypnotics, indicating that factors other than the child's health influence the use of hypnotic drugs in infancy and toddler years. The frequent usage of alimemazine in children below 3 years and the association with parents’ use of hypnotics should concern prescribing doctors.