Some people using hallucinogenic drugs can re-experience the effects of the drug days, weeks, or even years after they used it. This is called hallucinogen persisting perception disorder (HPPD).
These experiences are commonly called flashbacks. Read on to learn more about this phenomenon, why it happens, and how a person might experience it.
The common term “trip” refers to a drug-induced inner neurological experience in which sensory perception is altered while taking hallucinogenic drugs.
For many, this can be a life-enhancing experience. However, tripping on hallucinogens is potentially quite dangerous, depending on the following:
- the kind of hallucinogen
- the amount taken
- interactions with medications or underlying medical conditions
During some flashbacks, the sensation of reliving the trip or the effects of the drug is pleasant. It may actually be relaxing and enjoyable.
However, some people have a different flashback experience. Instead of a pleasurable trip, they experience perplexing visual effects only. These visual effects may include:
- halos around objects
- distorted sizes or colors
- bright lights that won’t fade
People experiencing these disturbances may be entirely aware of everything else that’s happening. The interruption in your field of vision can be annoying, disturbing, and possibly debilitating. That’s why these symptoms may be unsettling or upsetting.
If these visual disturbances occur frequently, you may have a condition called hallucinogen persisting perception disorder (HPPD).
While flashbacks are sometimes common, HPPD is considered rare. It’s unclear how many people experience this condition because people with a history of recreational drug use may not feel comfortable admitting this to their doctor.
Likewise, doctors may not be familiar with the condition despite its official recognition in medical curriculum and diagnostic manuals.
Researchers have recognized two forms of HPPD (type 1 and type 2). Type 1 HPPD is typically experienced as brief, random “flashbacks.” On the other hand, type 2 HPPD is generally long term, disturbing, and pervasive.
Because so few cases of HPPD are officially diagnosed, research is quite limited. That makes what doctors and researchers do know about the condition limited as well.
Read on to learn more about HPPD, the symptoms you might experience if you have it, and how you can find relief.
Flashbacks are a feeling that you’re reliving an experience from your past. Some flashbacks occur after drug use. Others may occur after a traumatic event.
People living with post-traumatic stress disorder (PTSD) experience flashbacks of stressful, even painful situations.
Both PTSD flashbacks and pleasurable drug flashbacks are often all-encompassing. In other words, during these flashbacks, all of your sensory information tells you that you’re reliving the event or trip, even if you’re not.
With HPPD, however, flashbacks are not as comprehensive. The only effect of the flashback you’ll experience is the visual disruption. Everything else will be the same.
You’ll be aware of the effects of the disturbances, but you likely will not enjoy the other effects of reliving a trip. As the flashbacks become more common, they can become frustrating, even overwhelming.
People who experience visual disturbances caused by HPPD often experience one or more of the following symptoms:
- Intensified colors. Colorful objects seem bright and more vivid.
- Flashes of color. Bold bursts of unexplained color may pop into your field of vision.
- Color confusion. You may have a difficult time telling similar colors apart, and you may also swap colors in your brain. What is actually red to everyone else may appear an entirely different color to you.
- Size confusion. Objects in your peripheral vision may appear larger or smaller than they really are.
- Halos around objects. When you’re looking at an object, a glowing rim may appear around it.
- Tracers or trailers. Lingering outlines of an image or object may follow or trail through your vision.
- Seeing geometric patterns. Shapes and patterns may appear in something you’re looking at, despite the pattern not really being present. For example, leaves on a tree may look like they make a checkerboard pattern to you but no one else.
- Seeing images within images. This symptom may cause you to see something where it isn’t. For example, you may see snowflakes in panes of glass.
- Difficulty reading. Words on a page, sign, or screen may appear to move or shake. They may also appear to be jumbled and undecipherable.
- Feeling uneasy. During an HPPD episode, you’ll know what you’re experiencing is not normal. This may make you feel as if something bizarre or unusual is happening, which can lead to an uncomfortable or embarrassing feeling.
It’s not clear how or why HPPD flashbacks occur, so one can happen at any time.
These flashbacks are rarely as intense or long lasting as a typical drug-induced trip.
It’s common for people with HPPD to experience:
While these symptoms are reported, the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) does not include them on the recognized list of symptoms. It is still unclear whether these symptoms are directly caused by the disorder.
Researchers and doctors do not yet have a solid understanding of who develops HPPD and why. It’s also unclear what causes HPPD in the first place. The strongest connection points to a history of hallucinogenic drug use, but it’s not clear how the type of drug or the frequency of drug use may affect who develops HPPD.
In some cases, people experience HPPD after their very first use of a drug. Other people use these drugs for many years before experiencing symptoms.
What does not cause HPPD is better known:
- HPPD is not the result of:
- Lingering symptoms are not the result of a bad trip. Some people may first develop HPPD after a bad trip, but not everyone with HPPD has experienced a bad trip.
- These symptoms are not the result of the drug being stored by your body and then released later. This myth is common, but not at all true.
- HPPD also is not the result of current intoxication. Many people first experience symptoms of HPPD days, weeks, even months after drug use.
If you experience unexplained hallucinations, it’s important to see a doctor. Any and all hallucinogenic episodes are of concern. This is especially true if you experience these episodes frequently. The doctor may perform an examination, obtain laboratory tests, and take an image of your brain.
In some cases, they may want to perform an electroencephalogram (EEG) to monitor the brain’s electrical activity.
If you’ve used hallucinogenic drugs, you should let your doctor know. It’s important to understand that your doctor’s primary concern will be helping you address and treat your symptoms. They are not going to judge your previous or recent drug use.
If the doctor performs a medical evaluation and the testing and imaging results are clear, they may recommend a psychiatric examination. If a psychiatric evaluation does not fit with other more common diagnoses, HPPD may be the resulting diagnosis.
Reaching an HPPD diagnosis may be easier if your doctor is familiar with the condition and your past drug use. Your doctor will want to know your personal health history, as well as a detailed account of what you’ve experienced.
If your doctor suspects another possible cause, such as side effects of a medication, they may request blood tests or imaging tests. These tests can help them eliminate other possible causes of your symptoms. If other tests come back negative, an HPPD diagnosis is likely.
To have an effective doctor-patient relationship, it’s important that you can be honest with your doctor about all your behaviors, choices, and health history. These factors will help your doctor reach a diagnosis and help you avoid possible complications from drug interactions.
If you feel your doctor is not treating you properly or taking your symptoms seriously, find a doctor who makes you comfortable.
HPPD has no recognized medical treatment. Since so little is known about the development of HPPD, it can be difficult to find a psychiatrist with experience treating it. Finding a way to ease the visual disturbances and treat the related physical symptoms may take a bit of trial and error.
Some people do not need treatment. In a matter of weeks or months, the symptoms may disappear.
Because the visual episodes of HPPD can be unpredictable, you may want to prepare yourself with techniques for handling the symptoms when they do happen. For example, you may need to rest and use calming breathing techniques if these episodes cause you significant anxiety.
Talk therapy could be a helpful coping option. A therapist or psychologist can help you learn how to respond to stressors when they occur.
HPPD is rare. Not everyone who uses hallucinogens will actually develop HPPD. Some people experience these visual disturbances only once after using hallucinogenic drugs. For others, the disturbances may occur frequently but not be very bothersome.
In some cases, symptoms of HPPD eventually go away, but others experience symptoms long term.
Little research exists to explain why HPPD occurs and how it’s best treated. For this reason, it’s important you work with a doctor to find a treatment technique or coping mechanisms that help you handle the disturbances and feel in control when they do occur.