Cleansing of the gastrointestinal tract to remove toxic substances, pills taken in overdose, or microorganisms. Activated charcoal or polyethylene glycol solutions (e.g., Golytely) given orally reduce the uptake of many drugs from the gastrointestinal tract. Before bowel surgery, oral antibiotics (e.g., neomycin) may be given to reduce the number of bacteria within the intestines.