 Some rebound or withdrawal adverse effects, such as the possibility of a sudden or severe emergence or re-emergence of psychosis in antipsychotic withdrawal, may appear when the drugs are discontinued, or discontinued too rapidly.While clinical trials of psychiatric medications, like other medications, typically test medicines separately, there is a practice in psychiatry (more so than in somatic medicine) to use polypharmacy in combinations of medicines that have never been tested together in clinical trials (though all medicines involved have passed clinical trials separately).It is argued that this presents a risk of adverse effects, especially brain damage, in real-life mixed medication psychiatry that are not visible in the clinical trials of one medicine at a time (similar to mixed drug abuse causing significantly more damage than the additive effects of brain damages caused by using only one illegal drug).