Perspective: preventive isoniazid therapy and the liver.

The preventive use of isoniazid (INH) has been controversial since 1975, but official agencies continue to advocate the procedure. Cost-effectiveness and risk benefit studies of preventive INH use have come to conflicting conclusions. A review of eight such studies indicates an increasing tendency to minimize INH hepatotoxicity and to disregard the declining tuberculosis morbidity and mortality in countries in which INH prophylaxis has not been widely adopted. We report three cases of fatal INH-associated hepatitis that illustrate that this complication of preventive INH use remains a serious problem. Current recommendations that encourage wide use of preventive INH therapy are unwise because they inflict a risk of fatal hepatitis on compliant adults and older children who have little danger of tuberculosis while being difficult to deliver to the alcohol- and drug-addicted persons whose risk is high. Health departments and physicians should severely restrict preventive INH therapy.