Table 5.

Categories and examples of use of medicines problems

	Definition	Examples
Unnecessary medicines use (overuse)	Use of a medicine that is not effective or needed for the target indication according to clinical evidence	Antibiotic* use for viral illnesses; vitamins, corticosteroids without appropriate indications; malaria treatment without proper diagnosis; fixed-dose combination products when one drug would suffice (eg, cough and cold remedies)
Failure to use needed medicines (underuse)	Lack of use of a medicine that is standard of care to effectively treat a target indication	Lack of treatment for patients with non-communicable diseases, including lack of treatment of mental illness; lack of secondary prevention combination therapy for patients with a history of cardiovascular events; underuse of opioids for cancer or other severe pain; lack of use of oral rehydration solution for patients with diarrhoea; poor adherence to treatment
Incorrect medicines use (misuse)	Use of the wrong medicine for the target indication and patient, or wrong use of the right medicine	Broad-spectrum antibiotics when narrow-spectrum antibiotics would suffice; teratogenic medicines used in pregnant women; coprescribing of absolutely contraindicated medicines; prescribing contraindicated medicines based on patient characteristics (eg, aspirin in children and adolescents for the treatment of fever); medicine dose not adjusted to patient age, weight, organ function; injections for patients who can swallow oral products; targeted cancer therapy use without confirming presence of targets
Unnecessary use of highly priced medicines	Use of a medicine that is more costly than a possibly equally effective and safe medicine	Use of originator brand products and branded generics when lower-priced quality international non-proprietary name generic products could be used; use of second-line and third-line medicines when first-line medicines should appropriately be tried first; use of new and highly priced medicines of questionable added value, when an older, better-characterised medicine would suffice (eg, new oral and injectable options for type 2 diabetes, new analogue insulins for type 1 diabetes)

^*For some therapeutic groups, such as antibiotics, addressing inappropriate use requires key interventions outside the health sector (eg, agriculture), which have been described elsewhere.²⁹⁶