LSD Toxicity Clinical Presentation

Updated: Jan 26, 2023
  • Author: Paul P Rega, MD, FACEP; Chief Editor: Stephen L Thornton, MD  more...
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History and Physical Examination

Although the use of hallucinogens, such as lysergic acid diethylamide (LSD), rarely results in presentation to health care facilities, patients who present to the emergency department for hallucinogen-related treatment typically do so after acute panic reactions (“bad trip”), massive ingestions, or unintentional ingestions (children or adults who have unknowingly ingested a hallucinogenic drug). [4] Altered perception can lead to behavioral toxicity, in which judgment is impaired and prevents an appreciation of the dangers in the environment, resulting in situations in which injury can occur.

Patients who present after recent hallucinogen abuse are often oriented and capable of providing a history of drug ingestion. The subjective effects of LSD use widely vary with the user's preconceived beliefs and expectations about the drug and the environment in which the ingestion occurred.

In general, hallucinogens can intensify the user’s current mood; pleasant feelings can be augmented to euphoric ones, with the achievement of new insights or an expanded consciousness. Negative feelings, personal flaws, or depressive symptoms can be amplified to a dysphoric experience. Changes produced in consciousness lead to loss of boundaries between the user and the environment. Users often report intensification or alterations of colors and sound (synesthesia) and the perception that common objects are novel, fascinating, or awe-inspiring.

Patients can also be agitated or withdrawn, with adverse reactions usually being seen in inexperienced users or in patients who have unknowingly taken the drug (although seasoned users can experience negative reactions as well). Children can appear agitated, withdrawn, or catatonic. In pediatric cases of known LSD intoxication, parental abuse or neglect must be assumed and investigated.

Drug-induced persistent psychosis manifests as distorted and disorganized thoughts, dramatic mood swings, mania, depression, vivid visual disturbances, and hallucinations that persist even after the drug effects have ended. Although rare, these symptoms may last for years.

Psychoactive/psychomimetic symptoms

Early effects from LSD, such as conflicting perceptual and mood changes, visual illusions, synesthesias, and extreme lability of mood, usually occur within 30 minutes after LSD intake. These effects may persist for up to 18 hours, even though the half-life of the drug is only 3 hours. [4]

More profound psychoactive effects peak at 2-4 hours.

The patient may perceive or experience the following [33] :

  • Feeling of inner tension, often relieved by laughing or crying
  • Multiple, simultaneous emotions, such as joy, rage, terror, or panic
  • Religiosity and a feeling of "oneness with the universe"
  • Possible distorted perception of the passage of time
  • Possible magnification or distortion of sounds
  • Illusions (or, with high doses, hallucinations)
  • Moving patterns of bright colors on people and objects
  • Geometric images within larger images
  • Trails behind moving objects
  • Halos around objects
  • Shapes blending together or melting like wax
  • Palinopsia - The persistence of a visual image in the brain long after the actual stimulus has gone [34]
  • Synesthesia - The mixing of sensory perception, such that the individual may see sounds or feel colors
  • Difficulties expressing thoughts and/or focusing on objects
  • Depersonalization

While the effects of LSD often are considered pleasurable to the user, at times they may be profoundly disturbing, resulting in a "bad trip." Novices, as well as seasoned users, can experience bad trips, common manifestations of which include the following:

  • Panic reaction - May be triggered by an unexpected stressful setting
  • Amplification of unconscious fears
  • Self aggression
  • Suicidal or homicidal ideation
  • Fear of going insane or of the inability to return to normal
  • Perception of rapid aging of self or others
  • Profound depression

Somatic symptoms

Patients who have taken LSD generally present with a combination of somatic and psychomimetic symptoms. [35] Somatic symptoms, which are usually due to sympathomimetic effects, include the following:

  • Mydriasis
  • Hypertension
  • Tachycardia
  • Flushing
  • Sweating
  • Loss of appetite
  • Nausea
  • Diarrhea
  • Dry mouth
  • Drowsiness
  • Sleeplessness
  • Weakness
  • Paresthesias
  • Tremors
  • Hyperactive reflexes
  • Piloerection
  • Mild pyrexia
  • Seizures - Rare; typically with doses above 10 μ g/kg

Manifestations such as tachycardia, hypertension, pupillary dilation, tremor, and hyperpyrexia can occur within minutes following oral administration of 0.5–2 µg/kg. [4]

As previously stated, massive overdoses can lead to respiratory arrest, coma (very rare), emesis, hyperthermia, autonomic instability, and bleeding disorders.

LSD has been found to be responsible for triggering serotonin syndrome in patients already using precipitating drug combinations (serotonin precursors or agonists, serotonin-release stimulators, selective serotonin reuptake inhibitors [SSRIs], nonselective serotonin-reuptake inhibitors, nonspecific inhibitors of 5-HT metabolism). [5] Moreover, patients taking SSRIs or lithium have greater potential for LSD-related complications, such as seizures and flashbacks. [36]

Hallucinogen persisting perception disorder 

Hallucinogen persisting perception disorder (HPPD) describes spontaneous, repeated or continuous recurrences of sensory distortions (flashbacks). Patients can have a combination of perceptual and visual disturbances during flashbacks, including the following:

  • Geometric hallucinations
  • Flashes of color
  • Moving light
  • Impaired color perception
  • Terrifying illusions (eg, people decomposing, crawling bugs, skulls, Satan's face superimposed on the faces of friends, objects melting)

These perceptual symptoms remain unchanged for long periods and often last for years after initial drug use. Such patients often present after previous negative workup for brain damage or psychiatric disorders. [17, 37]


Ergotism related to LSD ingestion is a possible, but extremely rare, complication. It is thought to be caused by ergot-derived lysergic acid amide (LSA) containing ergotlike precursors. Eponymously termed “Saint Anthony’s fire,” ergotism refers to ergot-induced vasoconstriction that leads to burning pain from limb ischemia, dry gangrene of fingers and toes, tissue desquamation, peripheral pulselessness, sensation loss, and edema. Ergotism can also present with convulsive symptoms leading to headache, paresthesias, seizures, and other central nervous system (CNS) effects, which are often preceded by GI symptoms such as nausea, vomiting, and diarrhea. LSD-induced ergotism often presents as vasoconstrictive effects in combination with hallucinations, mania, or psychosis. [38]


In rare cases, increased morbidity, or even mortality, has been associated with complications of hyperthermia, such as rhabdomyolysis, [39] myoglobinuric renal failure, hepatic necrosis, and disseminated intravascular coagulopathy.