A psychiatric diagnosis can only be made after determining that the symptoms are due neither to a general medical condition nor to use of a prescription or recreational drug. Many medical conditions may cause psychiatric symptoms, including endocrine, neurologic, and oncologic diseases, as well as vitamin deficiencies and infections. Many classes of drugs can induce symptoms of depression, anxiety, mania, and psychosis. Symptoms usually arise soon after drug initiation and are commonly related to high doses, polypharmacy, rapid titration, narrow therapeutic index, and stressful situations. Clinicians will benefit from this program which reviews the many drugs and conditions that may cause psychiatric symptoms.