To the Editor: Acetaminophen (marketed under such brand names as Tylenol, Datril, Tempra and Liquiprin) is widely advertised and used as an over-the-counter analgesic for patients who cannot take aspirin. Although generally substituted for aspirin because of the latter's tendency to erode gastric mucosa, acetaminophen has also been used when hypersensitivity to aspirin — an unusual phenomenon — occurs. Although cross-sensitivity between the two drugs must be extremely rare, we report here a case in which severe symptomatic thrombocytopenia seems to have been produced in a young man by both drugs.In 1972, when he was 29 years old, this . . .