Lysergic Acid Diethylamide (LSD)

Lysergic Acid Diethylamide (LSD)



Lysergic acid diethylamide (LSD), also known as "acid," belongs to a class of drugs known as hallucinogens, which distort perceptions of reality. LSD is the most potent mood- and perception-altering drug known: doses as small as 30 micrograms can produce effects lasting six to 12 hours.


In the United States, LSD has no accepted medical use and its manufacture is illegal.


LSD is produced synthetically from a fungus that grows on rye grass. This odorless, colorless, and slightly bitter-tasting chemical is generally ingested orally and absorbed from the gastrointestinal system. Manufacturers commonly distribute LSD in small squares of absorbent paper soaked with the drug, which users chew and swallow. Use of LSD and other hallucinogens by secondary school students has decreased since 1998, but has increased among older teens and young adults attending dance clubs and all-night raves, according to the National Institute on Drug Abuse.
LSD alters perceptions by disrupting the action of the neurotransmitter serotonin, although precisely how it does this is unclear. Studies suggest LSD acts on certain groups of serotonin receptors, and that its effects are most prominent in two brain regions: the cerebral cortex and the locus ceruleus. The cerebral cortex is involved in mood and perception, and the locus ceruleus receives sensory signals from all areas of the body. Natural hallucinogens resembling LSD, such as mescaline and psilocybin, have been used in social and religious rituals for thousands of years.
After its discovery in 1938, LSD was used experimentally to treat neuroses, narcotic addiction, autism, alcoholism, and terminally ill cancer patients, and to study the mechanisms of psychotic diseases like schizophrenia. Nearly 30 years after its discovery, manufacture, possession, sale, and use of LSD was restricted in the United States under the Drug Abuse Control Amendment of 1965.
LSD's effects generally begin within an hour of taking the drug and last for up to 12 hours. The drug is absorbed from the gastrointestinal tract, and circulated throughout the body and to the brain. It is metabolized in the liver and excreted in the urine about 24 hours after ingestion. Physical effects of LSD may include loss of appetite, sleeplessness, pupil dilation, dry mouth, salivation, palpitations, perspiration, nausea, dizziness, blurred vision, and anxiety, as well as increased body temperature, heartbeat, blood pressure, and blood sugar.
The major effects of LSD are emotional and sensory. Emotions may shift instantaneously from euphoria to confusion and despair, and users may feel as if they are experiencing several emotions simultaneously. Colors, smells, and sounds may be highly intensified, and time may appear to move very slowly. Sensory perceptions may blend in a phenomenon known as synesthesia, in which a person sees sounds, or smells colors, for example. Users may have out-of-body sensations, or may perceive their body has changed shape or merged with another person or object.


Unlike cocaine, amphetamines, heroin, alcohol, and nicotine, LSD is not considered addictive, but it is considered dangerous; users are at risk for several short- and long-term side effects. LSD's effects are unpredictable and may vary with the amount ingested and the user's personality, mood, expectations, and surroundings. Users may experience enjoyable sensations on some "trips," and terrifying feelings of anxiety and despair on others. Most LSD-related deaths stem not from the LSD's physical effects on the body, but from the panicked reactions ensuing from intense LSD-triggered illusions.

Side effects

Two long-term effects are associated with LSD use: psychosis, and hallucinogen persisting perception disorder (HPPD), also known as "flashbacks." The exact causes of these effects, including the mechanism by which LSD may cause them, is unknown. Chronic hallucinogen users or individuals with underlying personality problems are most vulnerable to these effects, but individuals with no history of psychological disorders have also experienced them. LSD-induced psychosis may include dramatic mood swings, loss of cognitive and communication skills, and hallucinations. Flashbacks generally involve seeing bright flashes, or halos or trails attached to moving objects after the LSD "trip" has ended. Flashbacks can last a few seconds or even several hours.

Key terms

Acid — Common street name for LSD.
Cerebral cortex — Brain region responsible for reasoning, mood, and perception.
Hallucinogen — A drug that distorts sensory perceptions and disturbs emotion, judgment, and memory.
Hallucinogen persisting perception disorder (HPPD) — The recurrence of LSD effects after the drug experience has ended.
Locus ceruleus — Brain region that processes sensory signals from all areas of the body.
Neurotransmitter — Chemical compound in the brain that transmits signals from one nerve cell to another.
Serotonin — A neurotransmitter that modulates the actions of other neurotransmitters in the brain.
According to the Drug Abuse Warning Network (DAWN), the number of LSD-related hospital emergencies is low compared to those related to cocaine, heroin, marijuana, methamphetamine, and other illicit drugs. One reason for this trend may be that LSD currently sold on the black market is less potent than in the past. LSD dose strengths tend to range from 20 to 80 micrograms today, compared to 100 to 200 micrograms reported during the 1960s and early 1970s.


LSD flashbacks can be spurred by use of drugs such as marijuana. Preliminary evidence suggests serotonin reuptake inhibitors like Prozac and Zoloft may also exacerbate the LSD flashback syndrome.



Aghajanian, G. K. and G. J. Marek. "Serotonin and Hallucinogens." Neuropsychopharmacology 1999: 16S-23S


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