Over 50% of all adverse drug reactions treated in hospitals and emergency care are preventable.

Many preventable drug reactions like drug overdoses and internal bleeding associated with the improper use of blood thinners and painkillers are life-threatening, especially in the elderly. There are many reasons for these reactions and may include poor coordination of care, lack of time and knowledge among health professionals, and lack of patient education, according to Swedish researchers, who conducted a meta–analysis of 22 studies. Human error is inevitable, and therefore systems must be made to reduce the error. The study concluded that:

1. In outpatient setting, the frequency of preventable adverse drug reactions resulting in hospitalization or emergency treatment is 2% and of these, 51% are preventable.
2. In the elderly, 71% of drug reactions are preventable.
3. In admitted patients the frequency of harmful drug reactions is 1.6% and 45% of them are preventable.
4. A third of preventable adverse drug reactions are life-threatening.