More than 1 million patients hospitalized in 2004 experienced adverse drug events (ADEs). Of these, 90% were adverse reactions related to drugs that were properly administered, according to data released by the Agency for Healthcare Research and Quality (AHRQ).

Overall, the top three drug types involved in ADEs were corticosteroids, anticoagulants, and antineoplastics. The drugs most often associated with drug poisoning (defined as accidental overdose, wrong drug given or taken in error, and drugs taken inadvertently) were benzodiazepines, opioids, aromatic analgesics such as acetaminophen, antidepressants, and anticonvulsants.

Patients who experienced ADEs from properly administered drugs tended to be older (on average, age 63) than those who had problems related to drug poisoning (on average, age 47). Nearly 60% of people who had an ADE were women, a percentage that mirrors their distribution in the hospital patient population.

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