In an age of medical specialization it is not unusual for a patient to visit within a short time a family doctor who prescribes an antibiotic for a strep throat, a psychiatrist who prescribes a tranquilizer, and a dentist who prescribes a painkiller. Some of these medications are compatible with each other and can be taken concurrently. But there are notable and alarming exceptions. For example, certain of the anticoagulant drugs used after a heart attack, in combination with aspirin, may increase the tendency toward internal bleeding. Some antihistamines, taken along with tranquilizers, may produce dangerously soporific effects.
The physician knows the...