Intravenous Magnesium Sulfate for Acute Nontraumatic Headache in the Emergency Department.

Abstract

The aim of this study was to determine whether intravenous MgSO₄ offers additional analgesic benefit when administered simultaneously with paracetamol in emergency department patients presenting with acute nontraumatic headache. In this randomized, double-blind, placebo-controlled clinical trial, adults presenting with acute nontraumatic headache received 1 g of oral paracetamol prior to randomization, then were assigned to receive either 2 g intravenous MgSO₄ in 150 mL saline solution or placebo 150 mL saline solution alone, infused more than 30 minutes. The primary outcome was the treatment success, defined as a ≥30% reduction in the numerical rating s̶cale score at 30 minutes. Secondary outcomes were the need for rescue analgesia, patient satisfaction, and adverse events. We included 506 patients in MgSO₄ group and 522 in placebo group. Success was more frequent in the MgSO₄ (78.9 %) versus placebo group (65.1%) (difference 13.8%; 95% confidence interval [CI] 8 to 19); however, all timed numerical rating s̶cale differences were below the 1.3-point accepted threshold for clinical importance. In the MgSO₄ group, rescue analgesia was required less frequently (7.1% versus 15.3%; difference -8.2%; 95% CI -12 to -4.3), patient satisfaction was greater (91.7% versus 85.1%; difference 6.6; 95% CI 2.7 to 10), and adverse events were more frequent (15.4% versus 11.1%; difference 4.3; 95% CI 0.1 to 8.4). Adding intravenous MgSO₄ to paracetamol achieved more frequent success in treating acute nontraumatic headache, but at levels below accepted thresholds for clinical importance. MgSO₄ was associated with less frequent rescue analgesia and a modest increase in mild side effects.