A class of mental disorders resulting from drug use (including alcohol), side-effects of medication, or exposure to toxins. There are 11 groups of substances specifically discussed in DSM-IV: alcohol; amphetamines and related sympathomimetics; caffeine; cannabis; cocaine; hallucinogens; inhalants; nicotine; opiates; phencyclidine and related drugs; and sedatives (2), hypnotics, or anxiolytics. However, many other substances, including heavy metals, rat poisons containing strychnine, carbon monoxide, and carbon dioxide can also lead to substance-related disorders. See alcohol-related disorders, amphetamine-related disorders, caffeinerelated disorders, cannabis-related disorders, cocaine-related disorders, hallucinogen-related disorders, inhalant-related disorders, nicotine-related disorders, opioid-related disorders, phencyclidine-related disorders, sedative-, hypnotic-, or anxiolytic-related disorders. See also substance-induced disorders, substance use disorders.