The efficacy of activated charcoal and ipecac syrup in the prevention of drug absorption was studied in 6 healthy adult volunteers, using a randomized, cross-over design. Paracetamol 1000 mg, tetracycline 500 mg and aminophylline 350 mg were ingested on an empty stomach with 100 ml water. Then, after 5 or 30 min, the subjects ingested, either activated charcoal suspension (50 g charcoal), syrup of ipecac, or, only after 5 min, water 300 ml. Activated charcoal, given either after 5 or 30 min, significantly (p<0.01 or=""><0.05) reduced="" the="" absorption="" of="" these="" 3="" drugs="" measured,="" for="" example="" as="">_0–24h. Syrup of ipecac caused emesis on each occasion, with a mean delay of 15 min. When ipecac was given 5 min after the drugs, its effect on absorption was significant, but when it was given after 30 min only the absorption of tetracycline was reduced. Activated charcoal was significantly (p<0.05) more="" effective="" than="" ipecac="" in="" reducing="" drug="" absorption="" when="" given="" at="" the="" same="" time="" points.="" in="" cases="" of="" acute="" intoxication,="" depending="" on="" the="" quality="" and="" quantity="" of="" the="" drugs="" ingested,="" the="" relative="" efficacy="" of="" charcoal="" and="" ipecac="" may="" be="" somewhat="" different="" from="" that="" observed="" in="" the="" present="" study.="" despite="" its="" emetic="" action,="" however,="" ipecac="" syrup="" is="" not="" very="" effective="" in="" preventing="" drug="" absorption="" and,="" in="" general,="" activated="" charcoal="" should="" also="" be="" given="" after="" induced="" emesis="" or="" gastric="">