A patient presents to your office with a 10-page typed out medical history. She states that she is “allergic” to twenty different medicines. Is she likely to have drug allergies or drug intolerances to most of these drugs?

Drug intolerance. Drug intolerances account for 90% of adverse drug reactions. An adverse reaction to a drug is an undesirable and usually unanticipated response independent of the intended therapeutic purpose of the medication. An adverse drug reaction may be either immunologic (i.e., drug allergy) or nonimmunologic (i.e., drug intolerance).