LSD is considered the typical hallucinogen and the characteristics of its action and effects apply to the other hallucinogens, including mescaline, psilocybin, and ibogaine. LSD was discovered in 1938. It is manufactured from lysergic acid, which is found in ergot, a fungus that grows on rye and other grains.
LSD is sold on the street as "acid" in tablets, capsules, and, occasionally, liquid form. It is odorless, colorless, and has a slightly bitter taste. It is usually taken by mouth. LSD is often added to absorbent paper, such as blotter paper, and divided into small decorated squares, with each square representing one dose.
The effects of LSD are unpredictable. They depend on the amount taken; the user's personality, mood, and expectations; and the surroundings in which the drug is used. The user usually feels the first effects of the drug 30 to 90 minutes after taking it. The physical effects include dilated pupils, higher body temperature, increased heart rate and blood pressure, sweating, loss of appetite, sleeplessness, dry mouth, and tremors.
Sensations and feelings change much more dramatically than the physical signs. The user may feel several different emotions at once or swing rapidly from one emotion to another. If taken in a large enough dose, the drug produces delusions and visual hallucinations. The user's sense of time and self changes. Sensations may seem to "cross over," giving the user the feeling of hearing colors and seeing sounds. These changes can be frightening and can cause panic.
Most users of LSD voluntarily decrease or stop its use over time. LSD is not considered an addictive drug since it does not produce compulsive drug-seeking behavior as do cocaine, amphetamine, heroin, alcohol, and nicotine. However, like many of the addictive drugs, LSD produces tolerance, so some users who take the drug repeatedly must take progressively higher doses to achieve the state of intoxication that they had previously achieved. This is an extremely dangerous practice, given the unpredictability of the drug.