A broad group of drugs that cause distortions of sensory perception. The prototype hallucinogen is lysergic acid diethylamide (LSD). LSD can cause potent sensory perceptions, such as visual, auditory, and tactile hallucinations. Related hallucinogens include peyote and mescaline.

A pattern or quantity of alcohol use which places the person at increased risk for alcohol related harm.This is defined by the WHO as more than 4 drinks in a day or more than 14 drinks per week for men under 65, or more than 3 drinks in a day or more than 7 drinks in a week for all women and for men over 65.