drug mixtures that include aspirin as one of the components, the others commonly being other analgesics (e.g., acetaminophen, codeine, propoxyphene), stimulants (usually caffeine), or both. Aspirin combinations may also include a barbiturate (e.g., butalbital), a skeletal muscle relaxant (e.g., carisoprodol, orphenadrine), or other drugs. Because many of these preparations can be obtained without a doctor’s prescription, individuals with the habit of regular self-medication are at risk of developing gastrointestinal symptoms (e.g., peptic ulcer) and other toxic reactions (see salicylism; caffeine intoxication).