LSD Side Effects

Learn about the LSD's side effects, including anxiety.

Summary and why care?

“This inquiry … indicates that with proper precautions [LSD and mescaline] are safe when given to a selected healthy group.”1

“An analysis of [occasional complications] suggests that with the application of certain safeguards many of the side effects might have been avoided.”1

“A large number of previous human trials indicate that LSD can be safely administered within a research or psychotherapeutic setting.”2

“if you look at the literature with clinical use, both with psilocybin and with LSD, you see that those drugs can be administered safely in research settings.”3

During use

Side effects

The effects generally last ~8 - 10 hours, with after effects noticable for perhaps another ~4 hours.

  • “The most common, but still infrequent, immediate problem was one of unmanageability.” “This apparently occurs when insight into the situation is lost and the individual acts upon delusory, usually paranoidal, ideas. Instances of running away from the tester, disrobing, or accidental self injury were described.”1
  • Panic related to the temporary “loss of ego”1
  • “An intense fear that [you] will not be able to get back to [your] ordinary state”1
  • Occasional appearance of catatonic state, particularly for people who experience somatization (“Somatization is a tendency to experience and communicate psychological distress in the form of somatic symptoms and to seek medical help for them. More commonly expressed, it is the generation of physical symptoms of a psychiatric condition such as anxiety.”4)
  • Anxiety or fearfulness.5 A 1955 paper found that anxiety occured in 9% more people who took 25-75 micrograms of LSD, and 14% more people who took 100-225 micrograms of LSD, compared with the placebo group.6
  • Paranoid thinking5
  • Nausea (rare in low doses, ~<125 micrograms) [^psychonaut-wiki-lsd]
  • Physical or psychological discomfort5
  • Transient moderate increases in blood pressure5
  • Suspiciousness or paranoid thinking7
  • Slight increases in blood pressure and heart rate2
  • Vasoconstriction2
  • Pupil dilation2
  • Increases in body temperature, blood glucose levels, sweat and saliva production2
  • Note: “LSD did not consistently produce any of these physiological effects except pupillary dilation, and none of the physiological changes were clinically significant.”2

After 8 hours

  • Don’t assume the trip is over when the effects are declining! “Three patients were left alone after the interview period [I believe this occured at 8 hours] was completed. The drug effects were declining and it was assumed that they were recovering uneventfully. Instead, they became increasingly tense and confused and required further therapeutic support. This exemplifies the importance of constant attendance even during the waning phase” of the psychedelic experience.1

Next few days

  • Usually after a night’s rest you can expect LSD’s effects to be completely absent, however persistence of anxiety or visual effects for another day or two has been described in literature1
  • Short-lived depression, perhaps caused by letdown after LSD-induced euphoria and self-transcendence, or related to an inability to integrate old memories that the LSD experience bought up1
  • Making regretful decisions either while on LSD or in the next day or two1

Serious risks

  • 5 day psychotic reaction in a subject with a schizophrenic twin1
  • Ingesting LSD without knowing what it is and what it does “represents a maximally stressful event.”8 A woman was given LSD without her knowledge, and she took her own life1
  • Impaired judgement leading to doing something dangerous or deadly. Best mitigated with a safe environment and a trusted and experienced sitter.

Side effects of fake LSD

  • It seems reasonable to say that the biggest risk of taking acid or LSD is actually in getting fake LSD. In particular, NBOMe substances carry acute toxicity risk and have been involved in a few deaths in the last few years9

See also: “My Friend Said it was Good LSD”: A Suicide Attempt Following Analytically Confirmed 25I-NBOMe Ingestion


Addiction risk appears low

Physiological addiction is unlikely, psychological habituation is conceivable but low1


“Some people who have used serotonergic hallucinogens, such as LSD or psilocybin, experience persistent and distressing alterations in perception, chiefly in the visual system, that last from weeks to years after use.”2

“An examination of previous reports and estimates of use of LSD and other hallucinogens use in the US suggests that HPPD is very rare (Halpern and Pope 2003).”2

Overall, current knowledge of HPPD remains very limited. In particular (1) the term ‘flashbacks’ is defined in so many ways that it is essentially valueless; (2) most studies provide too little information to judge how many cases could meet DSM-IV criteria for HPPD; and consequently (3) information about risk factors for HPPD, possible etiologic mechanisms, and potential treatment modalities must be interpreted with great caution. At present, HPPD appears to be a genuine but uncommon disorder, sometimes persisting for months or years after hallucinogen use and causing substantial morbidity. It is reported most commonly after illicit LSD use, but less commonly with LSD administered in research or treatment settings, or with use of other types of hallucinogens. There are case reports, but no randomized controlled trials, of successful treatment with neuroleptics, anticonvulsants, benzodiazepines, and clonidine. Although it may be difficult to collect large samples of HPPD cases, further studies are critically needed to augment the meager data presently available regarding the prevalence, etiology, and treatment of HPPD.10

A 2012 paper notes that “the antiepileptic lamotrigine may offer a promising new approach in the treatment of HPPD.”11

Psychotic reactions

“Strassman concluded that LSD might trigger psychotic episodes in people already vulnerable to psychosis rather than causing this reaction directly”2

“The occurrence of transient or persistent psychosis can be prevented or further reduced by screening subjects on the basis of past and current mental health and excluding people on the basis of the presence of past or current psychotic disorders or such disorders in first-degree relatives, such as biological parent or sibling.”2

“Cohen (1960) reported that only a single case of a psychotic reaction lasting more than 48 hours occurred in 1200 experimental (non-patient) research participants (a rate of 0.8 per 1000). Notably, the individual was an identical twin of a schizophrenic patient and thus would have been excluded under the proposed guidelines.”12

Psychedelic usage was associated with improved mental health indicators

“Lifetime classic psychedelic use was associated with a significantly reduced odds of past month psychological distress (weighted odds ratio (OR)=0.81 (0.72–0.91)), past year suicidal thinking (weighted OR=0.86 (0.78–0.94)), past year suicidal planning (weighted OR=0.71 (0.54–0.94)), and past year suicide attempt (weighted OR=0.64 (0.46–0.89))”13


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