Background Thalidomide is a chemotherapeutic agent approved by the EMA for multiple myeloma treatment. It is considered a high risk drug and should be prescribed and dispensed within a special pharmacovigilance programme.

Purpose To evaluate the incidence of adverse drug reactions (ADRs) to thalidomide; to analyse their type and severity.

Materials and Methods Retrospective cohort study, conducted between January 2008 and December 2011 in a university hospital. Patients treated with thalidomide were selected through the Pharmacy Department Outpatient Unit medicines records.

Patient clinical records were reviewed. Any doubts were checked with the attending physicians.

Data recorded: personal data (age, gender), main diagnosis, thalidomide ADRs, start and end dates of both thalidomide treatment and ADRs.

ADR incidence was calculated. Association between ADRs and thalidomide discontinuation was determined.

ADR causal relation was determined by the Karch Lasagna algorithm (definite, probable, possible, conditional). ADR type was classified according to the Rawlins and Thompson classification (type A: dose-dependent or type B: not dose-dependent) and ADR severity and outcome according to Spanish Pharmacovigilance System criteria.

Results Twelve patients were included (mean age 59 ± 12 years, 50% men).

Medical diagnosis: multiple myeloma 91.66% (11 patients) and cutaneous, vascular and digestive systemic sclerosis 8.3% (1).

The incidence of thalidomide ADRs was 83.3%. 8.3% (1) of treatment discontinuations were due to thalidomide ADR.

64.71% (11) of patients showed neurotoxicity, 17.64% (3) blood disorders, 11.76% (2) oedema and 5.88% of them (1) digestive disorders.

ADRs detected were type A (dose-dependent) in 100% of cases (17 patients), probable in 41.18% (7), and possible in 58.82% (10) of them.

Overall, 41.18% of ADRs were severe (7). ADR outcomes: 64.70% of ADRs (11 patients) were resolved, 17.65% (3) unresolved and 17.65% (3) were classified as ‘death unrelated to the drug’.

Every ADR detected was notified to the Spanish Pharmacovigilance System.

Conclusions Although the incidence of thalidomide ADRs was high (83.3%), ADRs only caused treatment discontinuation in 8.3% of cases.

Neurotoxicity was the most frequent ADR.

Almost half of patients had severe ADRs and these did not resolve in 17.65% of cases.

No conflict of interest.