LSD (lysergic acid diethylamide) is one of the major drugs making up the hallucinogen class. LSD
was discovered in 1938 and is one of the most potent mood-changing chemicals. It is manufactured
from lysergic acid, which is found in ergot, a fungus that grows on rye and other grains.
LSD, commonly referred to as "acid," is sold on the street in tablets, capsules, and, occasionally,
liquid form. It is odorless, colorless, and has a slightly bitter taste and is usually taken by mouth.
Often LSD is added to absorbent paper, such as blotter paper, and divided into small decorated
squares, with each square representing one dose.
The Drug Enforcement Administration reports that the strength of LSD samples obtained currently
from illicit sources ranges from 20 to 80 micrograms of LSD per dose. This is considerably less
than the levels reported during the 1960s and early 1970s, when the dosage ranged from 100 to 200
micrograms, or higher, per unit.
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. Usually, the user 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.
Users refer to their experience with LSD as a "trip" and to acute adverse reactions as a "bad trip."
These experiences are long - typically they begin to clear after about 12 hours.
Some LSD users experience severe, terrifying thoughts and feelings, fear of losing control, fear of
insanity and death, and despair while using LSD. Some fatal accidents have occurred during states
of LSD intoxication.
Many LSD users experience flashbacks, recurrence of certain aspects of a person's experience,
without the user having taken the drug again. A flashback occurs suddenly, often without warning,
and may occur within a few days or more than a year after LSD use. Flashbacks usually occur in
people who use hallucinogens chronically or have an underlying personality problem; however,
otherwise healthy people who use LSD occasionally may also have flashbacks. Bad trips and
flashbacks are only part of the risks of LSD use. LSD users may manifest relatively long-lasting
psychoses, such as schizophrenia or severe depression. It is difficult to determine the extent and
mechanism of the LSD involvement in these illnesses.
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. NIDA is funding studies that focus on the
neurochemical and behavioral properties of LSD. This research will provide a greater understanding
of the mechanisms of action of the drug.