Long-term effects on the liver.

Two or three decades ago chronic liver injury due to drugs was scarcely recognized. Today a wide range of diseases, previously thought to be due to 'natural' causes, is attributed to therapy, although final proof of the cause is often difficult or impossible to achieve. In addition, new drugs have been produced which have subsequently been shown to have hepatotoxic effects. These may only be manifest in a very small proportion of patients, and can even, as in the case of methotrexate, be avoided by judicious dose regimens; demonstration of a hepatotoxic effect therefore does not necessarily mean that an important and irreplaceable drug must be withdrawn from use. This paper deals only with therapeutic and prophylactic drugs. Other toxic substances, notably ethanol and plant poisons such as aflatoxin, almost certainly play a much larger role in chronic liver disease in man but will not be discussed here.