Objective To assess the efficacy of combined use of scorpion antivenom (SAV) with prazosin, compared with prazosin alone in children with Mesobuthus tamulus scorpion envenomation.

Study design Randomised controlled trial.

Setting A tertiary care hospital in south India.

Patients 50 children with definite history and/or systemic manifestations of scorpion envenomation were recruited from the paediatric emergency or outpatient department from February 2012 to July 2013.

Interventions The children were randomised into two groups. In 25 children, SAV was administrated as a slow intravenous bolus combined with prazosin (group A). Others received prazosin alone (group B). Results were analysed by Student t test and χ² test.

Main outcome measures Time required for resolution of autonomic symptoms, total dose of prazosin, adverse events.

Results Children in group A recovered earlier than those in group B (mean difference 9.1 h, 95% CI 6.0 to 12.2). 23 children (92%) in group A were clear of autonomic symptoms within 10 h, compared with 10 children (40%) in group B (mean difference 52%, 95% CI 29% to 75%). The proportion of children deteriorating to clinical grade 3 or 4 was 8% in group A as against 44% in group B (p<0.01). The mean dose of prazosin required was 54 µg/kg versus 130.8 µg/kg in group A and B, respectively (p<0.01). SAV was not associated with severe adverse reactions.

Conclusions Usage of SAV led to faster recovery and reduced the incidence of myocardial dysfunction. Combined therapy with SAV and prazosin is beneficial for children with M tamulus scorpion envenomation.

Trial registration number: CTRI/2013/09/004002 (Clinical Trials Registry of India).