Background Paediatric patients are one of the most vulnerable patient populations. There are many unlicensed medicines and the so-called ‘off-label’ uses for which they are prescribed may increase the risk of drug-related problems (DRPs) such as lack of efficacy and adverse drug reactions (ADRs).

Purpose The objective of this study is determine the incidence of DRPs for patients admitted to the hospital's paediatric emergency unit, and provide information about drug use, with the intention of improving the rational use of medicines.

Materials and methods A prospective observational study took place in July to September 2011. Pharmacists interviewed the people who were responsible for children up to 15 years old, without race restrictions, from both sexes, to obtain information about medicines the children had been taking. The results were evaluated and the DRPs were related to the admission to the hospital emergency paediatric unit of the State University Hospital of Campinas (UNICAMP). The DRPs obtained were classified as ineffective treatment, ADRs, inappropriate use, compliance, poisoning, drug interactions and technical defects.

Results The authors interviewed 348 patients or those responsible for them and the proportion of hospital admissions due to DRPs was 14.7% (51 patients). Among the DRPs identified, 23 (45.1%) were due to ineffective treatment, 11 (21.6%) due to ADRs, 9 (17.6%) to inappropriate use, 4 (7.8%) to non-compliance, 2 (3.9%) to intoxication, 1 (2%) to a technical defect and 1 (2%) to a drug interaction. The respiratory and gastrointestinal systems were the most commonly affected organs, and antipyretics/analgesics were the drugs most commonly associated with ADRs.

Conclusions This data may be used to construct the epidemiology profile of paediatric patients, showing that there is a high incidence of DRPs that cause hospitalisation. More study is necessary in both pharmacoepidemiology and pharmacovigilance in the paediatrics area to understand the DRPs involved and improve the use medicines in children.