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I remain deeply optimistic about psychedelic medicine. The research on psilocybin, depression, neuroplasticity, addiction, trauma, and psychological flexibility is changing our understanding of what may be possible when the brain and mind become temporarily more open to change. For many people, psychedelic experiences are meaningful, psychologically illuminating, spiritually profound, and sometimes life changing.
Supporting psychedelic medicine, however, also means being willing to talk honestly about the minority of people whose experiences do not unfold this way. Some people emerge from a psychedelic experience frightened, perceptually altered, disconnected from their bodies, or unable to feel that they have completely returned to their previous baseline. A person can have had several beautiful and healing psychedelic experiences and still have one experience that is overwhelming or destabilizing.
For some people, persistent perceptual changes may meet criteria for Hallucinogen Persisting Perception Disorder, usually abbreviated HPPD. HPPD is an uncommon and still poorly understood condition involving the recurrence or persistence of perceptual effects after the hallucinogenic substance itself is no longer active. It has been reported most commonly following LSD, but has also been associated with psilocybin, MDMA, cannabis, synthetic cannabinoids, and other psychoactive substances (Doyle et al., 2022; Martinotti et al., 2018).
Acknowledging HPPD does not require us to become anti psychedelic. It requires us to become more mature about psychedelic medicine. Powerful experiences can heal. Powerful experiences can also overwhelm. Both realities deserve our attention.
One of the most difficult aspects of HPPD is explaining it to someone who has never experienced it. A person may know intellectually that the psychedelic substance has left the body while continuing to experience changes in visual perception. Lights may produce halos. Objects may leave trails. Afterimages may remain after looking away. Stationary patterns can appear to shimmer or move. Some people see flashes, intensified colors, unusual geometric patterns, or a layer of visual static frequently described as visual snow.
Clinical reviews describe symptoms including palinopsia, trailing, halos, altered motion perception, flashes of light, intensified colors, visual snow, and distortions of size, shape, or depth (Martinotti et al., 2018). HPPD can overlap phenomenologically with migraine aura, visual snow syndrome, neurological conditions, anxiety disorders, and depersonalization or derealization, which is why competent medical assessment matters.
People with HPPD generally retain reality testing. They usually recognize that the perceptual phenomenon is coming from an alteration in their perception rather than believing that an objectively supernatural event is occurring. Yet knowing this intellectually does not necessarily make the experience less frightening.
That fear can create a second layer of suffering. A person notices an afterimage and becomes frightened. They look again to see whether it is still there. They begin testing their vision. Did the wall just move? Was that light always this bright? Was that visual static there yesterday? Soon the person may be monitoring perception dozens or hundreds of times a day.
The original visual symptom is now accompanied by hypervigilance.
Dr. Steven Locke, a Harvard trained psychiatrist who has developed a clinical focus on HPPD and visual snow, emphasizes that many people with these conditions struggle to find clinicians who understand what they are experiencing. His guidance includes obtaining appropriate psychiatric or neuropsychiatric evaluation, treating accompanying anxiety or depression, and avoiding further hallucinogens and cannabis when HPPD is suspected. He has also collaborated with Johns Hopkins researchers in efforts to better characterize HPPD symptoms.
This distinction is important because HPPD can become not only a perceptual problem but a problem involving the meaning we assign to perception. “Have I permanently damaged myself?” “Will this ever stop?” “Am I going insane?” “Will I ever feel normal again?” The nervous system can begin treating every perceptual change as evidence of catastrophe.
Not every difficult psychedelic experience is HPPD. Psychedelic experiences can include fear, grief, traumatic memories, paranoia, sensations of dying, loss of control, or frightening imagery without producing a persistent perceptual disorder.
In fact, difficult psychedelic experiences can sometimes become meaningful. Carbonaro and colleagues (2016) surveyed almost 2,000 people about their most challenging psilocybin experience. Many described the experience as among the most difficult of their lives, yet 84% also reported that they ultimately benefited from it.
Difficult is not automatically harmful.
At the same time, a smaller group experienced continuing psychological difficulties, and some sought professional treatment afterward. This is an important part of the psychedelic conversation. Most people may not experience long term harm, but the people who do struggle should not be dismissed because they are statistically uncommon.
I once attended a medicine retreat where participants were working with ayahuasca. One person attending the retreat had a significant history of religious trauma. They had been raised in an evangelical Christian household and had read extensively about the therapeutic potential of psychedelics. They had also spoken with people who believed psychedelic experiences had helped them heal from religious trauma. They came to the retreat hopeful.
During the ceremony, however, the experience moved in exactly the opposite direction. The people around them began appearing as demonic figures. The room seemed to turn red and was experienced as a level of hell. What made the experience particularly complicated was that many of the perceived demons were not behaving maliciously. Some seemed kind or supportive. But that did little to reduce the terror. For someone raised in a religious environment where demons, hell, punishment, and spiritual danger had once carried enormous emotional authority, this was not simply unusual psychedelic imagery. It activated some of their deepest conditioned fears.
By the following morning, the acute psychedelic effects had largely passed, but the emotional experience had not. Other people at the retreat were compassionate and tried to help them process what had happened. They attempted to reassure the person that psychedelic imagery did not need to be interpreted literally. Yet their anxiety remained overwhelming.
Eventually they left the retreat despite people encouraging them to remain where support was available.
I remember this experience because it illustrates something important about psychedelics. The same psychological openness that can make these experiences deeply therapeutic can also make a person unusually vulnerable to previously conditioned fear. The psychedelic did not create the person’s religious trauma. It entered a nervous system in which images of hell and demons already carried enormous psychological power.
This is why set and setting mean far more than the physical room. Developmental history is part of the setting. Religious conditioning is part of the setting. Trauma is part of the setting. Attachment history, expectation, fear, and previous experiences of authority are all present in the room with the person.
Sometimes even a supportive environment cannot prevent the nervous system from becoming overwhelmed.
In situations like this, I do not believe the first therapeutic question should necessarily be, “What did the demons mean?” Meaning can come later. First we may need to help the nervous system recognize something more basic, the ceremony has ended, the person is here, the body survived, and the feared hell realm is no longer happening.
Safety sometimes has to precede interpretation.
HPPD itself is a perceptual disorder. It is not the same diagnosis as posttraumatic stress disorder. But a person can develop a traumatic relationship to the symptoms.
Persistent perceptual changes can lead to panic, insomnia, avoidance, derealization, depersonalization, social withdrawal, and constant monitoring of the visual environment. Research into persistent difficulties following psychedelic use has documented experiences of anxiety, disconnection, existential confusion, depersonalization, and prolonged difficulty integrating what occurred.
A person may begin avoiding darkness because the visual phenomena become stronger. Music associated with the psychedelic experience may trigger panic. Meditation may become frightening because changes in consciousness remind the body of losing control. Even relaxation itself can become threatening.
At that point there may be two related therapeutic concerns, the perceptual phenomena themselves, and the nervous system that has become chronically organized around them.
HPPD is fundamentally a perceptual disorder. The person may continue to experience visual snow, afterimages, trailing, halos, altered motion perception, flashes of light, intensified colors, or other visual phenomena long after the psychedelic substance itself is no longer active. These experiences are real to the person and should not be reduced to anxiety, imagination, or psychological weakness.
At the same time, the perceptual symptoms can begin to generate a second layer of distress. A person may become frightened by what they are seeing and then begin monitoring perception constantly. An afterimage appears and the chest tightens. Visual snow becomes noticeable and breathing changes. A light leaves a halo and attention immediately collapses around it. The nervous system begins learning a very simple association, visual change equals danger.
This is where HPPD can begin to take on qualities that resemble traumatic stress. HPPD is not the same diagnosis as posttraumatic stress disorder, but a person can develop a traumatic relationship to persistent perceptual symptoms. They may become hypervigilant, avoidant, easily activated, dissociated, or frightened of their own sensory experience. They may begin avoiding darkness, music, meditation, cannabis, altered states, or anything that reminds them of the original psychedelic experience. The perceptual disturbance remains one part of the problem, while the nervous system’s ongoing response to that disturbance becomes another.
This is where somatic therapy can be useful. The purpose is not to treat the visual phenomena as though they are imaginary or to suggest that a person can simply think them away. Instead, somatic work focuses on how the body and nervous system are responding to the perceptual experience. We pay attention to breathing, muscular tension, autonomic activation, dissociation, posture, movement, orientation, relaxation, and the person’s ability to shift attention intentionally.
Somatic therapy can help restore a sense of agency by working slowly with orientation, relaxation, movement, bodily sensation, and the ability to shift attention intentionally. This is especially important when someone has spent weeks or months feeling as though their body is no longer a reliable place to live. Part of the work is helping the person recognize what safeness actually feels like in the body.
For some people, that sounds surprisingly unfamiliar. They may know intellectually that they are safe while their body remains braced, vigilant, or prepared for something to go wrong. In somatic work, we begin noticing very small signs of regulation. Perhaps the jaw softens. The breath becomes less restricted. The feet feel more connected to the ground. The eyes begin to move around the room rather than fixating on visual symptoms. The shoulders drop slightly. There may be a sense of warmth in the hands or a greater feeling of support from the chair.
These moments matter because safeness is not only an idea. It is also a physiological experience.
When the nervous system has become organized around threat, the therapeutic task is often to help the person become increasingly familiar with the bodily experience of not being in immediate danger. We are not forcing relaxation or asking someone to convince themselves that everything is fine. We are helping them notice the moments when the body is already moving toward greater regulation and then learning how to stay in contact with those moments a little longer.
This may involve orienting to the room and recognizing what feels neutral or reassuring. It may involve noticing the steadiness of the floor under the feet, the support of the chair, the rhythm of breathing, or the presence of another safe person. It can also involve gentle movement, stretching, walking, or allowing the body to complete impulses that were interrupted during a frightening psychedelic experience.
The goal is not to create a permanently calm nervous system. That is neither realistic nor necessary. The goal is flexibility, helping the person recognize when activation is increasing, recognize when greater safeness is available, and develop the capacity to move back toward regulation rather than becoming trapped inside escalating fear.
If a visual disturbance repeatedly triggers panic, the nervous system may begin responding as though an immediate threat is present. Somatic therapy can help slow that sequence down. Rather than immediately trying to eliminate the perception, we become curious about what happens in the body when it appears. Does the breathing stop? Does the stomach tighten? Do the shoulders rise? Does attention narrow? Does the person begin scanning or checking immediately?
Then we begin widening the field of experience. The visual snow is present, and the feet are also touching the floor. The afterimage is present, and the chair is supporting the body. A perceptual change is occurring, and there is also the sound of a bird outside, the sensation of breathing, the presence of another person in the room, and the awareness that this moment is different from the psychedelic experience that originally felt overwhelming.
The therapeutic aim is not denial. It is helping the perceptual symptom stop becoming the entire field of consciousness.
Hypervigilance can magnify suffering. What we repeatedly monitor becomes increasingly salient. Anxiety does not necessarily create HPPD, but anxiety can substantially intensify the person’s relationship to the perceptual experience. The more closely someone checks whether a symptom is still present, the more psychologically central that symptom can become.
Part of the work is therefore helping the person develop a different relationship to perception. Instead of immediately moving from “I see something unusual” to “Something terrible is happening,” there can gradually be more space between perception and interpretation.
The person may begin learning, “This visual effect is present, but I am not in immediate danger.” “My perception feels different, but I can still orient to the room.” “I can notice this without having to monitor it.” “I can experience this sensation and remain connected to my body.”
Over time, the person can begin learning something very different from the association that initially developed around HPPD. Instead of visual change equals danger, the nervous system begins developing a more nuanced response, visual change may be uncomfortable, but I can orient, I can breathe, I can feel my body, I can recognize where I am, and I can return toward safeness.
That learning matters.
A person who has become frightened of their own perception may gradually discover that they can experience an unusual visual phenomenon while still remaining connected to the present moment. The symptom may be there, but the body does not have to mobilize as though catastrophe is occurring.
This is one of the central aims of somatic work, not eliminating every uncomfortable sensation, but helping the person build a reliable pathway back toward safeness in the body.
The more familiar that pathway becomes, the less helpless the person may feel when symptoms appear. The nervous system begins learning that activation is not permanent, that perception can change without becoming an emergency, and that there are ways of returning to greater steadiness, connection, and embodied presence.
The person is not being asked to force themselves into relaxation or pretend they feel safe. Instead, the work involves noticing small moments in which the body does not feel completely threatened. Those moments can gradually become more available and more believable.
Over time, the aim is to help the person move from constant vigilance toward greater flexibility. The perceptual experience may still be present, but it no longer has to determine the person’s emotional state, attention, or identity.
The person can begin moving from “Something is wrong with me” toward “I am experiencing a perceptual disturbance that my nervous system is learning how to relate to differently.”
That shift is clinically meaningful.
It moves the person away from catastrophic interpretation and toward agency, orientation, safeness, and a greater capacity to live alongside what they are experiencing while recovery continues.
Derealization and depersonalization can be among the most frightening experiences following a difficult psychedelic state. The person may intellectually recognize their surroundings while experiencing the world as artificial, dreamlike, distant, or somehow unreal. They may feel disconnected from the body or emotionally separated from themselves.
Trying to think one’s way out of this experience often becomes frustrating.
Somatic work begins more simply.
Where are your feet? What happens when you press them gently into the floor? Can your eyes orient naturally around the room rather than checking for symptoms? Can you notice where the door is? Can you feel the weight of the body in the chair? What temperature do you notice in your hands? Can you hear my voice and also notice the sounds outside?
These may sound like small interventions. But when a nervous system has become organized around threat, small experiences of orientation and choice matter.
The person is gradually learning again that the present moment is different from the overwhelming altered state.
HPPD does not yet have a universally accepted treatment protocol. Pharmacological evidence remains limited and consists largely of case reports, case series, and small studies. Reviews have described improvement in some individuals receiving medications such as clonazepam, clonidine, lamotrigine, or certain anticonvulsants, while responses vary substantially and some medications have reportedly worsened perceptual symptoms (Neven & Blom, 2025).
This is one reason self medication is a poor strategy.
Someone experiencing persistent visual disturbances should be assessed by a clinician familiar with HPPD, visual snow, migraine, psychiatric conditions, and neurological differential diagnoses. In many cases, treatment will involve more than one discipline.
Medical care can address diagnosis and possible pharmacological options. Psychotherapy can address fear, shame, depression, trauma, derealization, hypervigilance, and the loss of trust in one’s own nervous system.
These approaches do not need to compete.
One of the most painful traps in HPPD is the belief that life must remain suspended until perception becomes completely normal.
“I’ll return to work when the static disappears.”
“I’ll travel when my vision is normal again.”
“I’ll date when I stop feeling strange.”
“I’ll relax when I know this is completely gone.”
Soon the person’s entire life becomes conditional.
Part of recovery may therefore involve reclaiming life while the nervous system is still changing. Going outside again. Exercising. Seeing friends. Working. Creating. Resting. Developing intimacy. Experiencing pleasure without immediately checking whether symptoms are still present.
The shift is from “I am a person with HPPD” toward “I am a person who is currently experiencing HPPD.”
That distinction matters.
A symptom can be real without becoming an identity.
People struggling after psychedelic experiences frequently carry shame.
“I should have known better.”
“I did this to myself.”
“I ruined my brain.”
These conclusions rarely help.
People use psychedelics for many reasons. Some are seeking healing from trauma or depression. Some are exploring consciousness. Some participate in spiritual traditions. Some are curious.
An adverse reaction is not evidence of moral failure.
Nor does someone become anti psychedelic simply because they need help after a difficult experience.
A person can believe that psychedelics have tremendous healing potential and still say, “Something happened to me that I did not expect, and I need help.”
A mature psychedelic culture should make room for that sentence.
For years much of the psychedelic movement understandably focused on correcting decades of fear based misinformation. That was necessary. Psychedelics are not the uniformly destructive drugs they were once portrayed as being, and modern research has demonstrated substantial therapeutic potential.
But psychedelic medicine is now mature enough to acknowledge complications without imagining that doing so undermines the entire field.
If psychedelics are powerful enough to produce profound healing, they are powerful enough to occasionally produce difficult consequences.
When someone says that something went wrong, the response should not be, “Psychedelics are dangerous and should never be used.”
Nor should it be, “You must have done something wrong.”
The better response is, We believe you. Let’s understand what happened. Let’s help your nervous system recover.
HPPD appears to be uncommon, but statistics are not particularly comforting to the person waking up each morning with visual snow, trails, afterimages, derealization, or the fear that perception has permanently changed.
The encouraging news is that the symptom does not have to become the organizing principle of a person’s life.
Appropriate medical and psychiatric evaluation can help clarify what is occurring. Existing literature suggests that some medications may help selected individuals, although treatment remains under researched. Avoiding further psychedelic exposure and cannabis is commonly recommended when HPPD is suspected. Psychotherapy can address anxiety, depression, shame, traumatic stress, derealization, and the constant monitoring that sometimes develops around perceptual symptoms.
Somatic therapy offers a way to work with the part of the person that may still feel as though the psychedelic experience has not completely ended, the body that remains braced, the eyes that keep checking, the breath that stops when the visual disturbance appears, and the nervous system that has forgotten what ordinary safeness feels like.
We work gradually. We restore orientation. We restore agency. We help the nervous system recognize the difference between an unusual perception and immediate danger. We help the person begin recognizing safeness again, not only as an intellectual conclusion, but as something that can be experienced through breath, movement, contact with the floor, relationship, orientation, and the body’s own capacity to settle.
Over time, we help the person return to movement, relationship, creativity, intimacy, work, nature, and ordinary life.
Psychedelic experiences can be profound and beautiful. They can also be frightening. Sometimes both things are true in the same person’s life.
When something does go wrong, people should not have to navigate it alone.
Recovery can mean more than waiting for perception to become exactly what it was before.
It can mean developing a different relationship with perception, rediscovering agency, and learning again that the body can become a place of safeness, orientation, and connection.
HPPD and persistent perceptual disturbances should be evaluated by qualified medical and mental health professionals because similar symptoms can occur with migraine, visual snow syndrome, neurological disorders, medication reactions, substance effects, anxiety disorders, depersonalization, and other conditions. This article is educational and does not provide individual medical advice.
The medicine retreat vignette describes an experience personally observed by the author rather than a psychotherapy client. All client scenarios in the published version are used by permission and identities anonymized.
Carbonaro, T. M., Bradstreet, M. P., Barrett, F. S., MacLean, K. A., Jesse, R., Johnson, M. W., & Griffiths, R. R. (2016). Survey study of challenging experiences after ingesting psilocybin mushrooms: Acute and enduring positive and negative consequences. Journal of Psychopharmacology, 30(12), 1268–1278.
Doyle, M. A., Ling, S., Lui, L. M. W., Fragnelli, P., Teopiz, K. M., Ho, R., Di Vincenzo, J. D., Rosenblat, J. D., Gillissie, E. S., Nogo, D., Ceban, F., Jawad, M. Y., & McIntyre, R. S. (2022). Hallucinogen persisting perceptual disorder: A scoping review covering frequency, risk factors, prevention, and treatment. Expert Opinion on Drug Safety, 21(6), 733–743.
Kuhfuß, M., Maldei, T., Hetmanek, A., & Baumann, N. (2021). Somatic experiencing: Effectiveness and key factors of a body oriented trauma therapy. A scoping literature review. European Journal of Psychotraumatology, 12(1), 1929023.
Locke, S. (2026). HPPD help and HPPD FAQ. Steven Locke, MD.
Martinotti, G., Santacroce, R., Pettorruso, M., Montemitro, C., Spano, M. C., Lorusso, M., di Giannantonio, M., & Lerner, A. G. (2018). Hallucinogen persisting perception disorder: Etiology, clinical features, and therapeutic perspectives. Brain Sciences, 8(3), 47.
Neven, A., & Blom, J. D. (2025). Pharmacological treatment of hallucinogen persisting perception disorder: A systematic review. Harvard Review of Psychiatry, 33(5), 264–275.
van de Kamp, M. M., Scheffers, M., Hatzmann, J., Emck, C., Cuijpers, P., & Beek, P. J. (2023). Body and movement oriented interventions for posttraumatic stress disorder: An updated systematic review and meta analysis. Journal of Traumatic Stress, 36, 967–980.