Hallucinogens

Hallucinogens are drugs which affect perception, sensation, thinking, self-awareness and emotion.

Other names/examples:
Psychedelics, LSD, Mescaline (from the Peyote cactus), psilocybin (from a mushroom found in Mexico), morning glory seeds, DMT, DOM (STP), PMA, MDA, Shrooms.

What do they do to you?

Basically, they make you "lose touch" with reality. The effects vary greatly according to the dosage, the personality of the user, and the conditions under which the drug is used. Illusions and hallucinations often occur and such "breaks with reality" can last from a few days to months. The sense of time and of self is altered. Sensations may seem to "cross over" -- that is, music may be seen or color heard. Physical reactions can range from minor changes such as dilated pupils, a rise in temperature and heartbeat, or a slight increase in blood pressure to tremors. High doses can greatly alter your state of consciousness. Sometimes flashbacks can occur. A flashback is a recurrence of some feature of a previous hallucinogen experience days or months after the last dose. Flashbacks may be spontaneous, or they may be triggered by physical or psychological stress, by medications such as antihistamines, or by marijuana. Heavy use of hallucinogens seems to produce flashbacks more frequently and it can also cause brain damage.