All drugs, including essential drugs, can be used irrationally. Irrational use is widespread in both developing and industrialized countries; it occurs in public and private sector health facilities and in the home. Many of the gains of efficient selection, procurement and distribution can be lost by irrational prescribing and by lack of adherence to treatment by the patient.
Irrational drug use has both medical and economic consequences. In medical terms, inappropriate treatment may lead to unnecessary suffering and death, to iatrogenic disease and hospital admissions, and to increased antimicrobial resistance. Irrational drug use also decreases public confidence in the health care system and attendance rates of curative and preventive services. Economically, irrational drug use leads to an enormous waste of resources and to unavailability of essential drugs in other areas where they may be needed.