[Occurrence of drug reactions]

The aim of this prospective study was to evaluate the incidence of allergic reactions to drugs compared to other kinds of medical emergencies admitted to the main Hospital in Milan during a 6 months period. At the same time we drew a list of drugs most frequently involved in allergic reactions, and a list of the most frequent symptoms. Using special forms, the medical staff collected patients' data: age, history of atopy, identification of the drug causing the reaction, and any previous reactions. Among 11,407 cases of medical emergencies, we found 163 (1.43%) patients showing drug reactions: the mean age was 27.3; 58.90% were female; atopy was present in 16.56%. The drugs most frequently involved were: pyrazon group (22%); ASA (20.86%); penicillin and derivatives (9.20%); sulfa drugs (6.14%); group B vitamins (4.30%); tetanus toxoid (4.30%); hyposensitizing extracts (3.68%); propionic acid derivatives (2.46%); paracetamol (1.84%); indomethacin (1.23%); rifampicin (1.23%); erythromycin (1.23%); glafenine (1.23%); others (17.80%). Urticaria and/or angioedema were the most frequent symptoms (86.51%), then anaphylactic shock (9.81%) and asthma (3.68%) with regard to anaphylactic shock only 6.20% of the patients had had a previous reaction to the same drug. From these data we can see that the incidence of drug reactions is very low compared to other medical emergencies; penicillin evidenced fewer reactions than expected, while the pyrazon group and ASA confirmed the data from literature.