Acetaminophen should be used cautiously in patients with anemia since this condition can be aggravated. Cyanosis may not be apparent in patients with preexisting anemia, in spite of dangerously high blood concentrations of methemoglobin. Acetaminophen should be used cautiously in asthmatic patients who also have aspirin hypersensitivity. Acetaminophen was administered in doses of 1000 mg and 1500 mg. The majority of the reactions were mild bronchospasm and were easily reversed.
Phenothiazines can interfere with thermoregulation.
Concomitant use of acetaminophen with phenothiazines can produce hypothermia if acetaminophen is given in large doses and the patient is exposed to cold ambient temperatures. The risk of developing hepatotoxicity from acetaminophen appears to be increased in patients who regularly consume ethanol. In these patients, hepatotoxicity is possible even at normal, therapeutic dosages of acetaminophen. Administration of acetaminophen should be limited or avoided altogether in alcoholics or patients who consume ethanol regularly. In rats, cimetidine decreases acetaminophen binding to hepatic microsomal proteins and cimetidine has been shown to improve survival after acetaminophen overdose.