Objectives: To assess efficacy and safety of two equine F(ab')2 antivenoms currently used to treat envenoming by European vipers.
Design: Retrospective case review study.
Setting: Case records collected by the Swedish Poison Information Centre concerning patients treated in Swedish hospitals for bites by the common European adder, Vipera berus.
Subjects: Patients presenting with V. berus envenoming treated with antivenom (n = 30) and two groups of patients not given antivenom (n = 16 and n = 38).
Main outcome measures: Clinical course and time in hospital were retrospectively studied and compared in patients treated or not treated with antivenom.
Results: There was a significantly lower incidence of extensive oedema (23 vs. 88%) and anaemia (10 vs. 50%) in the antivenom-treated group, and the hospital stay was shorter (median: 3 vs. 6 days). Antivenom treatment also resulted in prompt clinical improvement in the acute phase. Adverse effects consisting of urticaria and serum sickness occurred in 10% of the patients given antivenom.
Conclusions: Antivenom treatment was associated with a reduced morbidity in severe V. berus envenoming. However, the occurrence of allergic side-effects is not negligible with this type of antivenom.