Hyperprolactinaemia is a common side effect of antipsychotics; markedly raised levels are less common. Higher levels of prolactin result from longer exposure to higher doses, especially with older antipsychotics or with risperidone, sulpiride or amisulpride. Galactorrhoea, gynaecomastia, menstrual abnormalities and sexual dysfunction including hypogonadism and fertility problems are consequences of raised prolactin, and in the longer-term bone demineralisation. Younger patients may be more susceptible to hyperprolactinaemia. Trial reports often fail to state the frequency of raised levels.