Hallucinogen-persisting perception disorder, or HPPD, causes a person to keep reliving the visual element of an experience caused by hallucinogenic drugs. But what do the flashbacks in HPPD feel like, what causes them, and how might they be treated?

A person with HPPD has frequent visual disturbances. They do not relive any other aspects of a drug trip, only the part that involved vision. The way the flashbacks in HPPD affect a person's vision can be frustrating and may cause anxiety.

This article explores the symptoms and causes of HPPD. It also discusses how a person experiencing HPPD can manage their condition.

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A person with HPPD has frequent visual disturbances, which may cause anxiety.

Unlike the immersive flashbacks that some people have after taking drugs, HPPD flashbacks are purely visual. This means that a person with HPPD just has visual disturbances, such as seeing blurry patterns, size distortion, and bright circles.

These individuals do not relive any other aspects of the feeling of being on drugs.

HPPD flashbacks are not usually pleasurable, and they can become annoying if they occur frequently or last for a long time. The flashbacks may also cause anxiety.

HPPD does not cause people to have full hallucinations or delusions.

Someone experiencing HPPD is usually aware that it is a visual disturbance and can determine what is real, as a 2012 study explains. This qualifies HPPD visual disturbances as pseudohallucinations.

HPPD can affect the way a person perceives visual input.

According to a 2016 review, there are two types of the condition:

  • Type 1: This is where people experience HPPD in the form of random, brief flashbacks.
  • Type 2: People with this kind of HPPD experience ongoing changes to their vision, which may come and go.

The visual disturbances a person with HPPD may experience include:

  • Seeing halos or auras around objects — for instance, street lights or stars might appear to have a ring or fuzzy boundary around them.
  • Seeing trails that follow moving objects — when an object moves, a trail might appear behind it.
  • Changes in color perception — sometimes, colors can be hard to distinguish or may appear as a completely different color.
  • An object can appear to be moving when it is still.
  • Seeing a pattern on an object that others cannot see — these are often geometric, like a checkerboard, for instance.
  • Air looks like it is grainy or textured — this is sometimes called visual snow.
  • Dimensions of an object may be altered — for instance, an object may seem to change shape or, similarly, objects in peripheral vision might appear larger or smaller than they are.

Experiencing the symptoms of HPPD can be distressing.

It is usually apparent to a person experiencing HPPD that they are not seeing things in the way they used to. This can be unnerving and may cause anxiety.

What are flashbacks?

A flashback feels as if the individual is relieving something that happened in the past.

In conditions such as post-traumatic stress disorder (PTSD), they can be particularly intense. It truly feels as if you have gone back in time. All the information from your eyes, ears, and other senses tells you that you are living through an event for a second time.

However, in HPPD, they tend to be less intense — it is mostly vision that is affected, rather than the other senses. They can be frustrating if they occur frequently.

To date, scientists still do not know exactly how or why they occur. Researchers are still working on the question.

Related conditions

Some people with HPPD experience visual disturbances alongside other symptoms. These may include:

Depersonalization disorder is a mental health condition where a person may feel like:

  • they are disconnected to their body
  • they are observing life, rather than experiencing it
  • the world around them is foggy or distant

Researchers do not fully understand how these conditions relate to HPPD, but many report that they experience them alongside visual disturbances.

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A person with HPPD may experience visual disturbances, such as bright circles and blurry patterns.

Researchers believe that people are at risk of experiencing HPPD if they take hallucinogenic drugs recreationally. However, they do not yet understand the type or frequency of drug use that causes it.

According to a 2003 study, HPPD is reported most commonly after illicit use of LSD. There are also reports of people who have only used hallucinogens once or twice experiencing similar symptoms.

HPPD is not caused by brain damage or a mental disorder. It is also not the result of current intoxication or by an amount of a drug staying in a person's system. Nor is HPPD caused by a "bad trip." These are all common beliefs about HPPD that are not true.

More research is needed to understand the changes in the brain that cause HPPD symptoms.

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Disclosing any past drug use will enable the doctor to give an accurate diagnosis.

If a person is experiencing visual disturbances, they should speak to their doctor.

There are some other conditions that could be the cause. As such, the doctor may ask a number of questions to reach a diagnosis.

It is important to be open and honest about any past drug use, to help the doctor reach the correct diagnosis.

A person's relationship with a doctor is confidential. The doctor is there to provide the best course of treatment and not judge lifestyle choices.

Most doctors do have an awareness of HPPD as a condition. If a doctor is not sympathetic to a person's symptoms or does not want to explore HPPD as a diagnosis, then it is a good idea to speak to a different doctor.

There is no one recommended course of treatment for HPPD. However, there are two drugs that initial research suggests may be effective. These are:

  • Lamotrigine: According to a 2012 case study, this antiepileptic, mood-stabilizing medication may help to relieve symptoms. Researchers found lamotrigine to be more effective than other drugs, including antipsychotics and selective serotonin reuptake inhibitors (SSRIs), which made symptoms worse in some people.
  • Clonazepam: A 2015 case study found that the tranquilizer clonazepam might also be an effective treatment for HPPD symptoms.

The effectiveness of drug therapy can vary from person to person. Every person who has visual disturbances as a result of HPPD experiences them slightly differently.

The 2012 study also recommends the following to help manage symptoms:

  • avoiding illicit drugs
  • reducing stress
  • treating related conditions, such as anxiety or depression

HPPD symptoms may cause anxiety. In turn, stress and anxiety may make HPPD symptoms worse. Trying mindfulness, yoga, or meditation may help to reduce stress and anxiety.

Most people who experience HPPD only have symptoms for a short time after drug use. However, there are examples of people experiencing HPPD symptoms over a number of years.

A doctor can help provide advice on managing HPPD symptoms and may prescribe a course of drug therapy to help.

As researchers come to understand more about the condition, a more extensive range of treatments may become available.