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Intoxication from LSD and other common hallucinogens

João Delgado, MD
Section Editor
Stephen J Traub, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM


"Hallucinogen" describes substances whose primary effects include the alteration of sensory perception, mood, and thought patterns. Naturally occurring hallucinogens have been used for millennia as part of ritual and religious activities. The first synthetic hallucinogen, lysergic acid diethylamide (LSD), was synthesized in 1938 by the chemist Albert Hofmann. Its hallucinogenic properties were recognized by accident in 1943 when Dr. Hofmann was inadvertently exposed to LSD while working in his laboratory [1]. LSD was initially marketed as an anesthetic agent and touted as an adjunct for psychoanalysis. In the 1960s, LSD emerged as a recreational drug. Its popularity peaked in the late 1960s and early 1970s and has been declining since. The drug was banned under United States federal law in 1966.

Hallucinogens are used for their so-called psychedelic effects. These desired effects involve heightening or distortion of sensory stimuli and enhancement of feelings and introspection. Most hallucinogens produce sympathomimetic effects, including tachycardia, hypertension, mydriasis, hyperthermia, and diaphoresis, but these are generally mild [2]. Nausea and vomiting are common and often precede the onset of hallucinogenic effects.

The clinical features, diagnosis, and management of intoxication from LSD and other prototypical hallucinogens (including dextromethorphan, some phenethylamines (mescaline, 2C-B, 2C-T-7), psilocybin and other tryptamines, and Salvia divinorum) are reviewed here (table 1). Amphetamines, methamphetamines, MDMA, ketamine, and phencyclidine (PCP) are discussed separately. (See "Methamphetamine: Acute intoxication" and "MDMA (ecstasy) intoxication" and "Ketamine poisoning" and "Phencyclidine (PCP) intoxication in adults".)


Lysergic acid diethylamide (LSD) remains the prototypical hallucinogen and the most extensively studied of such drugs. Approximately 1.2 million persons in the United States aged 12 or older are categorized as current hallucinogen users [3]. Hallucinogens account for approximately 7 percent of United States emergency department (ED) visits involving illicit drugs [4]. Hallucinogen use occurs worldwide, although the prevalence is generally considered to be low relative to other drugs of abuse [5]. LSD has been supplanted as the most common hallucinogen by the so-called new psychoactive substances, such as synthetic cannabinoids (eg, K2, spice) and “club drugs,” and naturally occurring hallucinogens, such as psilocybin and Salvia divinorum [5,6]. This is thought to be related to a number of factors, including the decreased supply of LSD, the rapid emergence of new psychoactive substances, and the ready availability of other hallucinogens via the internet [7,8].


A hallucination occurs when a person experiences sensory perceptions in the absence of external stimuli. True hallucinations can occur with recreational hallucinogen use. However, the alterations in perception commonly caused by these drugs are more accurately termed illusions because there is often a basis in reality for the sensory perception.

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Literature review current through: Nov 2017. | This topic last updated: Sep 20, 2017.
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