Accidental drug overdose, or prescription of the wrong drug, or incorrect drug administration can poison the patient, causing illness or death. Some patients are hypersensitive to certain drugs, and so an ordinary dose can harm them. Adverse drug effects include severe allergic drug reactions, chronic effects and internal chemical burns.
All manner of drugs can be poisonous, including local anaesthetics, diuretics, xanthine derivatives, drugs acting directly on the musculoskeletal system, liniments, ointments, diagnostic drugs and pharmaceutical dyes. Poisoning can occur via absorption, ingestion, inhalation or injection into the body.
One review found that almost 11% of older patients' emergency room visits were due to medication complications.