Twelve adult volunteers were given 24 81-mg aspirin tablets and were randomly assigned into the following treatment groups: (1) control aspirin, (2) 30 mL of ipecac repeated if vomiting not induced, (3) 60 g of activated charcoal per 15 g of magnesium sulfate (MgSO4), and (4) ipecac repeated if needed, followed by activated charcoal/MgSO4 given 1 1/2 hours after the last vomiting episode. All treatments began 60 minutes following aspirin ingestion. Urine was collected for 48 hours for percent total salicylate excretion. Mean +/- SD recovery of salicylate from urine was as follows: aspirin, 96.3% +/- 7.5%; ipecac 70.3% +/- 11.8%, activated charcoal/MgSO4, 56.4% +/- 12%; and ipecac and activated charcoal/MgSO4, 72.4% +/- 14.1%. Ten subjects completed the study. In group 4, eight of ten subjects vomited the activated charcoal/MgSO4 immediately, making statistical analysis impossible. Analysis revealed that activated charcoal/MgSO4 significantly lowered the absorption of aspirin compared with the control and ipecac-treated groups. Furthermore, ipecac significantly lowered aspirin absorption compared with the control group. We conclude that activated charcoal/MgSO4 used alone is superior to the other treatment modalities at inhibiting the absorption of multiple aspirin tablets.