Patients with hepatic impairment may have: reduced capacity to metabolise, reduced ability to synthesise, and reduced hepatic blood flow. Liver function tests (LFTs) are a poor marker of hepatic metabolising capacity, as the hepatic reserve is large. There are few clinical studies relating to the use of psychotropic drugs in people with hepatic disease. The development of metabolic syndrome may be linked to the emergence of non‐alcoholic fatty liver disease later in treatment. Of those treated with antidepressants, 0.5‐3% develop asymptomatic mild elevation of hepatic transaminases. Almost any type of liver damage can occur, ranging from mild transient asymptomatic increases in LFTs to fulminant hepatic failure. Using drugs in patients with renal impairment needs careful consideration. This is partly because some drugs are nephrotoxic but principally because the pharmacokinetics of drugs are altered in renal impairment.