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LSD: Coming To Terms With Flashbacks

HPPB, Hallucinogen Persisting Perception Disorder, is the medical term for the flashbacks that many former LSD users experience. Flashbacks can be terrifying. They can be unexpected and distracting. And they can last for years.

LSD is an extremely powerful mood and perception-altering drug, a hallucinogen. The hallucinations caused by taking this drug can last for 6-12 hours, even in small doses. And the potential for dependence is high. But these hallucinations are different from what is felt by the user months and years after they stop using the drug. Many people assume that LSD flashbacks mimic the hallucinations experienced during the drug use, but HPPB is a very different animal. It is one of the most common long-term effects of LSD.


The slang term “flashbacks” refers to repeated and sudden distortions in the senses. Most often they are visual disturbances, and both a warping of what is actually before the person or things that aren’t even there.

These symptoms may be caused by changes deep within the brain, but are not (as earlier research suggested) remnants of the drug still circulating in the body.

Here are the most common visual disturbances that former LSD users say they have experienced:

  • Impaired perception of colors
  • Moving light around the edges of objects
  • Flashes of color
  • Seeing geometric shapes that aren’t there
  • Seeing frightening illusions
  • Halos or trails of light from objects

Someone with HPPB may make the rounds of several medical professionals, trying to find out what is causing these symptoms, not realizing that they are related to the former LSD use. Unfortunately, some people with HPPB have almost continuous episodes of visual and perceptual disturbances, so frequently that it interferes with their daily life.

Treatment for HPPB is supportive, since there is no known cure yet. Anti-depressants seem to help.


Bertrand T

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