You might still see visual oddities long after the effects of psychedelics wear off. ‘‘Flashbacks” could be a symptom of HPPD.

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Some people who have taken psychedelics, like LSD or psilocybin (“magic mushrooms”), might experience an “endless trip” long after the more intense or intoxicating effects of these substances have worn off.

Sometimes referred to as “flashbacks,” the physical symptoms could cause the world to look “brighter” or more vibrant than usual.

Examples of flashbacks from psychedelic use include seeing random flashes of light while driving or watching words move on the page of a book while you’re reading, as though they’re “dancing.”

Emotional symptoms could also be present, which might confuse or frighten you.

These are all symptoms of hallucinogen persisting perception disorder (HPPD), a treatable condition psychedelic substance use could trigger.

HPPD refers to when someone reexperiences visual and emotional sensations that can surface with psychedelic use after a substance is out of your system.

The physical symptoms of HPPD are a type of “flashback” similar to what you might experience with post-traumatic stress disorder (PTSD), except it’s visual and not always distressing.

HPPD is a rare condition recognized as an official diagnosis in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), and ICD-11 linked to the use of psychoactive substances including:

  • cannabis
  • DMT
  • ketamine
  • LSD
  • MDMA (ecstasy)
  • peyote
  • psilocybin (magic mushrooms)

How is HPPD diagnosed?

HPPD, first documented in 1954, has two main clinical diagnostic criteria: experience taking hallucinogens and visual distortions once you’re no longer under the influence.

But emerging research shows that the definition of HPPD may need to be expanded.

One study found that 50% of people with HPPD had nonvisual experiences, and 38% developed symptoms unrelated to taking a hallucinogen.

For these people, the alterations in perception changed from physical to psychological. This could mean hallucinogens may trigger longer-term brain changes.

A 2020 study says tinnitus (ear ringing) can also be linked to previous use of substances, suggesting that HPPD may include more than only visual distortions.

People diagnosed with HPPD each experience this condition differently. Some people might experience symptoms for a few days after being intoxicated. Others might have symptoms for months or even years after using psychedelics.

A review of research shows that symptoms of HPPD can be broken up into two main categories: Type I and Type II HPPD.

Type I HPPD

This type of HPPD might include random, brief, and mild visual distortions that could be noticeable but cause little emotional distress.

When you experience Type I HPPD, you’re usually aware that your visual changes aren’t real, although your sense of time may feel as if it’s been altered.

Type II HPPD

Type II HPPD may be ongoing and persistent in nature, with visual distortions that may cause moderate to more intense emotional distress.

In this case, the symptoms may even interfere with your daily activities or quality of life. Type II HPPD may also lead to anxiety or depression symptoms.

HPPD is typically a rare condition, and reports of its symptoms tend to vary. How symptoms of HPPD are experienced is generally unique to each person with the condition.

Still, there are some visual symptoms many people with HPPD have in common.

Symptoms of HPPD can be divided into either physical or emotional symptoms. Physical symptoms are usually experienced visually, while emotional symptoms are psychological.

Physical symptoms

Physical symptoms of HPPD are generally experienced as visions or visual irregularities, including:

  • afterimages (seeing something after it’s gone)
  • blurring images
  • changing colors
  • enhanced visuals
  • eyespots, “snow,” or “floaters”
  • flashes of light or colors
  • geometric patterns
  • glowing objects
  • halos around objects
  • trails after a moving object

One review of case studies and case series found that 76% of those with HPPD also experience micropsia or macropsia or “Alice in Wonderland” syndrome. The syndrome causes people to feel as if their body changes in size.

Emotional symptoms

Not everyone with HPPD experiences emotional symptoms of this condition.

Experiencing visual disturbances with HPPD might be distressing. This may cause emotional or psychological symptoms for some people, which could include:

Studies estimate that roughly 4% of people who have used psychedelics experience HPPD. The exact number is difficult to come by.

This could be due to underreporting because psychedelic substances are illegal in most places, and symptoms of Type I HPPD are usually less distressing, especially if they resolve quickly.

Stigma exists around psychedelics and substance use. Some people may feel ashamed to tell their doctor that they’ve used psychedelics, which could lead to cases of HPPD going undocumented.

More research is needed to understand why HPPD symptoms develop in some people who use psychedelics and not others.

Still, several factors appear to be linked, which may point to possible causes of HPPD:

  • At least one dose. Research from 2018 shows that some people may experience HPPD after just one trip on a hallucinogenic substance. Others notice symptoms after using substances on multiple occasions over a long period of time.
  • Substance use disorders. According to a 2020 study, 100% of participants who developed HPPD had a prior substance use disorder, particularly with cannabis or benzodiazepines (Xanax, Clonazepam).
  • Stress. Research from 2020 shows that symptoms can be triggered or made worse by episodes of stress.

Related conditions

A review of studies indicates a link between HPPD and other co-occurring mental health conditions that may impact mood, including:

Though HPPD is rare, it’s a highly treatable condition. HPPD can be an ongoing condition for some people, but one study found that at least one-third of people with HPPD went into remission.

The most common treatment options for HPPD may include:

Like all mental health conditions, developing a treatment plan that works best for you may take time. You may have to try several approaches or multiple strategies at once.

If you think you may be experiencing HPPD, it can be especially beneficial to be upfront with your doctor about symptoms.

While stigma can make it hard to talk about substance use, the more information clinicians have, the better they can help you find the best treatment options for you.

Medication

There is no FDA-approved protocol for treating HPPD. All medications that are sometimes prescribed for HPPD are considered to be “off-label.”

Some common medication options include:

According to a 2021 study, Ropinirole, a common Parkinson’s medication prescribed to help activate dopamine receptors, reduced symptoms of HPPD in a 20-year-old male. However, more research is needed in this area.

Therapy

You don’t have to go through HPPD symptoms alone.

Talk therapy is a front-line treatment option for many conditions with HDDP, such as anxiety and depression.

A compassionate mental health professional can help you:

  • manage episodes and symptoms of HPPD
  • offer coping skills
  • help you feel more “in control” of what’s happening

Self-care

Stress can make HPPD symptoms worse. Planning self-care coping skills that can reduce your fight, flight, or freeze response and calm anxiety quickly can be helpful.

Some coping skills for managing symptoms of HPPD include:

Getting prepared

Being prepared as much as possible for how you’ll respond to HPPD symptoms could be helpful, especially with more intense episodes.

For example, if you’re driving, you may need to pull over. If you’re at work, you may consider designating a quiet, private place to wait for visual distortions to pass.

If you feel comfortable, telling a few trusted people what you’re going through at home, school, or work could be beneficial. You can even come up with a code word to signal that you’re having an episode or need some extra support.

The more prepared you are, the more empowered you may feel.

Experiencing symptoms of Type I or Type II HPPD after using psychedelics can make some people feel distressed or confused. If you have HPPD, you’re not alone.

HPPD is a rare but treatable condition. Many people develop treatment plans to manage the symptoms and live well-balanced lives.

Some people find that the most helpful approach to managing HPPD is tackling symptoms from multiple angles, including:

  • talk therapy
  • medication
  • stress management and self-care
  • preparing a plan for coping with flashbacks

If you’re living with HPPD, the APA Psychologist Locator can help you make the first step toward finding support.