Psychiatric disorders are common in medical inpatient and outpatient populations. As a result, internists commonly are the first to see psychiatric emergencies. As with all medical problems, a good history, including a collateral history from relatives and friends, physical and mental status examination, and appropriate laboratory tests help establish a preliminary diagnosis and treatment plan. Patients with suicidal ideation usually have multiple stressors in the environment and/or a psychiatric disorder (i.e., a major affective disorder, dysthymic disorder, anxiety or panic disorder, psychotic disorder, alcohol or drug abuse, a personality disorder, and/or an adjustment disorder). Of all patients who commit suicide, 70% have a major depressive disorder, schizophrenia, psychotic organic mental disorder, alcoholism, drug abuse, and borderline personality disorder. Patients who are at great risk have minimal supports, a history of previous suicide attempts, a plan with high lethality, hopelessness, psychosis, paranoia, and/or command self-destructive hallucinations. Treatment is directed toward placing the patient in a protected environment and providing psychotropic medication and/or psychotherapy for the underlying psychiatric problem. Other psychiatric emergencies include psychotic and violent patients. Psychotic disorders fall into two categories etiologically: those that have an identifiable organic factor causing the psychosis and those that have an underlying psychiatric disorder. Initially, it is essential to rule out organic pathology that is life-threatening or could cause irreversible brain damage. After such organic causes are ruled out, neuroleptic medication is indicated. If the patient is not agitated or combative, he or she may be placed on oral divided doses of neuroleptics in the antipsychotic range. Patients who are agitated or psychotic need rapid tranquilization with an intramuscular neuroleptic every half hour to 1 hour until the agitation and combativeness are under control. Haloperidol (Haldol) is the safest neuroleptic. Chlorpromazine (Thorazine), perphenazine (Trilafon), and, in the elderly, thiothixene (Navane) can also be useful if haloperidol (Haldol) is not effective and more sedation is needed; these drugs, however, produce more side effects. Violent patients need to be physically restrained and then given antipsychotic medication or, in the case of drug abuse or alcohol withdrawal, the appropriate drug management.(ABSTRACT TRUNCATED AT 250 WORDS)