The purpose of this study was to evaluate whole gut lavage with polyethylene glycol electrolyte solution (Colyte), as a potentially adjunctive measure in lowering serum acetaminophen levels. The effect of bowel lavage was evaluated on serial serum acetaminophen concentrations after 2-g and 4-g doses in 7 and 12 male patients, respectively. Mean peak level of serum acetaminophen after 2 g (60 min after intake) was not significantly lowered by bowel lavage. After 4 g, peak acetaminophen serum levels were significantly lower after bowel lavage (65.4% of controls, P < 0.001). Urinary concentrations of the mercapturic acid conjugate of the toxic metabolite were also significantly reduced by lavage (55% after 2 g and 45% after 4 g, P < 0.01). Activated charcoal given orally after administration of 4 g of acetaminophen had no significant effect on peak serum levels and had no additive effect on lavage. These studies suggest that rapid, complete bowel lavage with a polyethylene glycol electrolyte solution may be beneficial as an adjunct to the treatment of the acetaminophen intoxication.