Psychotropic drugs may have a variety of endocrine and metabolic side effects which may be harmful to patients, and which may lead to poor compliance with their medication regimen. Lithium may inhibit thyroid function, particularly when given in combination with valproate, carbamazepine or quetiapine. Thyroid function tests should be periodically monitored in patients taking lithium, and thyroid hormone replacement therapy given if hypothyroidism develops. Children taking stimulants or atomoxetine for ADHD may have anorexia and a resulting slowing of growth. Efforts to increase caloric intake, along with drug holidays, may be needed to counteract this tendency. Several antipsychotic medications elevate serum prolactin, which may result in hypogonadism. Switching to a prolactin-sparing antipsychotic medication may be helpful; alternatively, addition of aripiprazole (an antipsychotic with partial dopamine agonist activity) to the patient’s regimen may correct the hyperprolactinemia. Atypical antipsychotics may produce insulin resistance, weight gain, hyperglycemia and hyperlipidemia. Switching to a more metabolically neutral drug may be beneficial, or initiation of weight loss programs or medications may help. Finally, valproate has been shown to lead to the development of the polycystic ovary syndrome in young women. Monitoring the patient’s menstrual history is necessary to detect this condition. Choosing a different mood stabilizer is helpful, and use of an oral contraceptive may avoid the development of menstrual irregularity and hirsutism in patients taking valproate.