Visual Hallucinations: Causes and Medical Warning Signs
Author: Ukrainian Psychological Hub · Published: October 9, 2026 · Editorial Policy
Visual hallucinations are experiences of seeing something when no corresponding object or event is present in the external environment. A person might see a person standing in a room, an animal crossing the floor, colored geometric patterns, lights, shadows, or intricate scenes. The images can be vivid, fleeting, unsettling, neutral, or even familiar. What causes them depends on the person's vision, brain function, health, medications, sleep, and the circumstances in which the experience occurs.
The most important medical point is that visual hallucinations have several possible causes, including eye disease and vision loss, delirium from an acute illness, Parkinson's disease and dementia with Lewy bodies, migraine aura, seizures, medications, substance effects, and psychiatric disorders. A visual hallucination on its own does not establish schizophrenia, dementia, psychosis, or any other diagnosis. Clinical assessment looks for the pattern surrounding the experience. A major clinical review of neurological and ophthalmological visual hallucinations emphasizes asking about the experiences directly, reviewing vision and physical and cognitive health, and identifying the underlying condition.
A new visual hallucination accompanied by sudden confusion, trouble speaking, weakness, fever with severe illness, a seizure, impaired consciousness, or rapid deterioration requires prompt emergency assessment. Isolated recurrent images in someone with established vision loss and clear awareness may have a different explanation, but still merit an appropriate medical or eye evaluation. The NICE delirium guideline and the CDC's stroke warning signs explain why associated acute changes matter.
What Are Visual Hallucinations?
A visual hallucination is a perception experienced as visual despite the absence of an external stimulus that would normally account for it. Clinicians may distinguish elementary experiences, such as flashes, spots, colored shapes, or patterns, from complex or formed hallucinations involving faces, people, animals, objects, and scenes. This distinction can inform the evaluation, although neither form identifies a particular disease on its own. The review Visual Hallucinations explains how vision loss, brain networks, and neurological disorders contribute to different presentations.
Some experiences seem located in ordinary space: a figure appears in a doorway or a small animal on a chair. Others are superimposed on the person's surroundings, occur in darkness, or have a patterned appearance. Episodes can last seconds, minutes, or longer, recur frequently, or change with light and fatigue. Some people recognize immediately that the image is unreal; others are uncertain or convinced it is present. Insight is useful information for a clinician, but it is neither a stand-alone safety test nor a diagnostic test.
A hallucination differs from an illusion, in which a real stimulus is misperceived. Mistaking a coat on a chair for a person in low light is an illusion; seeing a detailed person when nothing corresponding is there may be a hallucination. Visual distortions, such as objects seeming unusually large or small, afterimages, visual snow, floaters, flashes, and blind spots can also be described as 'seeing things.' These phenomena need their own differential diagnosis, particularly when accompanied by new vision changes.
When Are Visual Hallucinations a Medical Emergency?
Immediate medical assessment is necessary when a visual hallucination is part of a sudden change in brain function or an unsafe situation. Call emergency services if the person becomes suddenly confused or difficult to awaken; develops trouble speaking, one-sided weakness, new severe headache, sudden trouble seeing, or difficulty walking; has a seizure that is prolonged or followed by prolonged confusion; has severe agitation or is unable to remain safe; or expresses an immediate intention to harm themselves or someone else. In the United States, call 911 for a medical emergency. Use the local emergency number elsewhere. Do not drive yourself when stroke-like symptoms or altered awareness are present.
The CDC's guidance on stroke symptoms identifies sudden vision problems, weakness, speech disturbance, balance problems, and severe unexplained headache as emergency warning signs. A hallucination together with these symptoms must never be casually attributed to migraine, stress, or a preexisting psychiatric condition.
An abrupt change over hours or days, especially in an older adult, a hospitalized person, or someone with an infection, fever, dehydration, recent surgery, medication change, or serious illness, raises concern for delirium. Delirium can fluctuate: the person may seem relatively clear in one conversation and severely inattentive or confused later. Some people become withdrawn and quiet rather than visibly agitated. NICE specifically identifies acute changes in attention, perception, functioning, and behavior as reasons for a delirium assessment.
Arrange same-day or otherwise urgent clinical advice for a first unexplained hallucination, a rapidly increasing frequency of episodes, a new hallucination with substantial sleep disruption or behavioral changes, or a hallucination linked to a recent medication adjustment. The threshold for urgent evaluation is lower when the person is medically unwell, immunocompromised, an older adult, or unable to give a reliable history. Do not leave someone alone if they are confused, disoriented, distressed, or at risk of injury.
What Causes Visual Hallucinations? The Main Clinical Categories
The underlying causes fall into several overlapping groups. Determining the likely explanation involves the person's age, baseline vision and cognition, whether the visual experience occurred while fully awake, the duration and repetition of episodes, recent illnesses, the medication list, substance exposure, and associated changes in neurological or mental state. The MedlinePlus clinical encyclopedia and O'Brien and colleagues' review describe this broad differential.
Vision loss and Charles Bonnet syndrome
People with reduced visual input from eye or visual pathway disease can develop vivid visual images. This phenomenon is often called Charles Bonnet syndrome. It occurs in association with conditions such as age-related macular degeneration, glaucoma, retinal disease, or other significant vision impairment. A person may see faces, figures, animals, patterns, or architectural scenes despite otherwise being alert and able to reason clearly. The images may look entirely convincing even when the person understands they are generated by the visual system.
Charles Bonnet syndrome is a descriptive clinical syndrome associated with visual impairment, and clinicians evaluate for other causes of hallucinations before attributing the experience to it. Preserved orientation and insight, a clear vision-loss history, and visual rather than multiple sensory experiences can support the interpretation; they do not automatically exclude coexisting illness. The interdisciplinary 2020 consensus-based review discusses vision-related hallucinations and strategies including reassurance, vision optimization, environmental changes, and review of contributing conditions.
An eye examination can identify treatable vision problems and ensure that symptoms such as new flashes, floaters, a dark curtain over vision, eye pain, or sudden visual loss receive urgent ophthalmic evaluation. These symptoms can reflect acute eye disease and should not be presumed to be hallucinations or Charles Bonnet syndrome.
Delirium: sudden confusion from illness or physiological disturbance
Delirium is an acute disorder of attention and awareness associated with medical conditions, drugs or withdrawal, or multiple contributing factors. Visual hallucinations may occur alongside disorientation, disturbed sleep–wake cycles, impaired concentration, fluctuating alertness, and changes in behavior. Common triggers include infection, severe illness, metabolic disturbance, hypoxia, dehydration, surgery, and medication effects. A seemingly calm person can still have hypoactive delirium.
A family member may be the first to notice that the person is suddenly seeing strangers in the house, picking at objects in the air, misidentifying the environment, or drifting in and out of coherent conversation. The hallmark in this setting is the accompanying acute disturbance in attention and cognition. The appropriate priority is to investigate and manage the medical cause. The NICE guideline on delirium recommends assessment of recent fluctuating changes, including perception.
Parkinson's disease and dementia with Lewy bodies
Recurrent, detailed visual hallucinations can occur in Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies. People may see figures, children, animals, or groups of people in ordinary settings. Some also experience a fleeting sense that someone is nearby, a shadow passing in the peripheral field, or a real object being mistaken for something else. These experiences can occur in early or later stages and vary in their relationship to medications, sleep, vision, attention, and cognitive changes.
Visual hallucinations have particular diagnostic relevance in dementia with Lewy bodies when considered with fluctuating cognition, parkinsonism, and REM sleep behavior disorder, but one symptom is insufficient for diagnosis. Research on visual dysfunction in Lewy body dementia describes the contributions of visuospatial and visual-processing dysfunction. A 2025 systematic review of minor visual phenomena highlights variability across studies and assessment methods.
Management in Lewy body conditions needs medical expertise. Antipsychotic medications can sometimes worsen movement symptoms and cause severe sensitivity reactions in dementia with Lewy bodies or Parkinson's disease dementia. The NICE dementia guideline recommends first identifying distress triggers and using psychosocial and environmental approaches, with carefully limited use of antipsychotics only when clinically justified. Do not independently start, stop, or alter Parkinson's medicines or psychiatric medications.
Migraine aura and other transient visual phenomena
Migraine aura often causes flashing lights, zigzag lines, shimmering areas, or blind spots that develop gradually, spread across part of the visual field, and resolve. Under the International Classification of Headache Disorders, third edition, an individual typical aura symptom commonly lasts 5–60 minutes, and aura may occur with or without headache.
Migraine visual aura is generally an elementary or patterned phenomenon rather than a formed scene of people or animals. Its timing matters: gradual expansion and reversibility suggest one kind of mechanism, while a sudden fixed visual deficit raises a different set of concerns. A first episode, a marked change from prior migraine, new persistent loss of vision, or associated weakness or speech difficulty requires prompt medical assessment to exclude stroke and other conditions. A person's past migraine diagnosis does not explain every new visual event.
Seizures and focal neurological events
Focal seizures involving visual brain regions can generate brief flashes, colors, shapes, or more complex visual experiences. Seizure-related symptoms may be highly stereotyped, meaning they recur in nearly the same sequence each time, and can occur with changes in awareness, unusual sensations, automatisms, or a post-event period of confusion. Neurological examination and sometimes electroencephalography can help determine whether seizures are a plausible cause.
Rare structural or vascular disorders affecting visual networks can also produce hallucinations. Clinicians consider neurological imaging when the history, examination, sudden onset, persistent focal findings, or other red flags make it appropriate. A clinical review of visual hallucination differential diagnosis describes the role of clinical history, examination, electroencephalography, and imaging as targeted rather than automatic tests.
Medications, substances, and withdrawal
Prescription and nonprescription medicines may contribute to hallucinations, especially in combination with infection, impaired kidney or liver function, older age, or other vulnerabilities. Potential contributors vary by person and can include drugs affecting dopamine or acetylcholine systems, some sedating medications, and agents that alter sleep or alertness. Recreational substances, intoxication, and withdrawal states are additional possibilities.
Bring a complete list of prescribed drugs, over-the-counter products, recent dose changes, supplements, alcohol exposure, and substance use to the assessment. Accurate, nonjudgmental reporting is clinically important because the treatment of withdrawal or a toxic exposure differs from the treatment of a primary psychiatric disorder. MedlinePlus identifies drugs, alcohol, illness, sensory loss, and neurological disease among relevant causes. Do not abruptly discontinue a prescribed medication solely because hallucinations have occurred; contact the prescribing clinician promptly, or seek emergency treatment when acute red flags are present.
Sleep transitions, sleep deprivation, and related disorders
Vivid visual images sometimes appear while falling asleep (hypnagogic experiences) or on awakening (hypnopompic experiences). These events can occur in otherwise healthy people and may also be associated with sleep disorders. Profound sleep deprivation can affect perception and attention and may create a setting in which unusual experiences become more likely.
The timing relative to sleep is critical. A brief image at the edge of sleep has different diagnostic implications from repeated formed images in broad daylight alongside confusion, cognitive decline, or functional deterioration. Persistent or disruptive sleep-related experiences deserve evaluation, especially with excessive daytime sleepiness, sleep paralysis, or other symptoms pointing to a sleep disorder. The general NIMH psychosis resource includes sleep deprivation among potentially relevant contributors to psychotic experiences.
Schizophrenia and other psychiatric conditions
Visual hallucinations can occur during psychiatric illness, including schizophrenia spectrum disorders, mood disorders with psychotic features, and other psychotic presentations. They are evaluated in the context of delusions, disorganized thinking or behavior, mood episodes, functional changes, duration, and the exclusion of medical or substance-related explanations. Hearing voices is prominent in many psychiatric presentations, but the modality of a hallucination alone does not distinguish psychiatric from neurological causes.
Psychosis describes a clinical syndrome involving a disturbance in reality testing; it is not interchangeable with hallucination. A person can have a visual hallucination with preserved insight and without a psychotic disorder. Equally, a person with psychosis may have several symptoms, including delusions or disorganized thinking, that require specialist care. See the English Hub's psychosis overview and schizophrenia clinical guide for their separate diagnostic and treatment questions. The NIMH guide to psychosis stresses that psychosis can occur in multiple illnesses and does not automatically mean schizophrenia.
Why the Same Visual Symptom Can Have Different Meanings
One person might see a patterned flash during a familiar migraine; another might see a detailed figure after losing central vision; a third might report strangers in the room while becoming acutely disoriented with an infection. All three may use the words 'I saw something that wasn't there.' Their treatment pathways are different because their overall clinical patterns are different.
Features worth documenting include whether the images are simple or formed, the exact onset and duration, whether they occur in one or both visual fields, changes in lighting, associated headache, fever, confusion, sleep changes, cognitive symptoms, movement abnormalities, medications, and whether the person can recognize the experience as unusual. The phenomenology can guide questions and tests but cannot substitute for an examination or decide a diagnosis by itself.
Visual Hallucinations Versus Delusions, Illusions, and Visual Disturbances
A hallucination concerns a perceptual experience. A delusion is a strongly held belief that remains resistant to contrary evidence in a particular clinical context; a person may have either symptom, both, or neither. An illusion is a misinterpretation of a real object or stimulus. A flash or floater may arise within the eye rather than representing a hallucination, and visual aura may reflect transient neurological activity.
The distinction between insight and certainty deserves care. Someone with Charles Bonnet syndrome can be frightened by an entirely convincing image while still knowing that the object is absent. Someone with delirium may alternate between recognition and confusion. Clinicians evaluate the complete pattern, including attention, orientation, and functioning, instead of treating a single question such as 'Do you know it isn't real?' as a diagnostic shortcut.
How Clinicians Evaluate Visual Hallucinations
An evaluation usually starts with safety, timing, and a careful history. The clinician asks what was seen, when it began, how long it lasts, and what was happening immediately before and after. They assess recent illnesses, vision changes, sleeping patterns, medicines, substance exposure, trauma or headache, and the impact on daily life. Input from someone familiar with the person's usual functioning can be especially valuable when attention or memory is impaired.
Physical and neurological examination may include vital signs, hydration and oxygenation assessment, level of consciousness, concentration, orientation, visual acuity, eye findings, movement abnormalities, focal neurological signs, and examination for acute illness. Laboratory tests are guided by the clinical picture and might investigate infection, glucose or electrolyte disturbance, or organ dysfunction. Electroencephalography may be appropriate when seizures are suspected; neuroimaging may be considered when focal signs, abrupt unexplained onset, or another structural concern is present. A vision assessment is essential when ocular disease or new visual loss is plausible. O'Brien et al. recommend a transdiagnostic assessment that includes physical, cognitive, and eye health.
A psychiatrist may assess for a psychotic disorder when broader symptoms point in that direction. A neurologist may evaluate suspected seizures, Lewy body disease, or focal neurological pathology. An ophthalmologist may investigate impaired visual input or acute retinal symptoms. These specialties often work together, and the correct referral depends on the presentation.
Questions to prepare before an appointment
Write down the first date, whether the experience is changing, the approximate frequency, duration, lighting conditions, and descriptions of what was seen. Note whether it affected one eye, seemed located in one side of vision, or coincided with dizziness, headache, poor sleep, changes in awareness, or new medication. Record the impact on driving, walking, falls, work, relationships, and sleep, and bring the medication list. A person who is confused or acutely unwell needs immediate clinical attention rather than documentation first.
Treatment Depends on the Cause
There is no single treatment for every visual hallucination. Delirium requires prompt treatment of precipitating medical problems and supportive care. Vision-related hallucinations may improve with correction of reversible eye problems, suitable lighting, education, and coping strategies. Migraine management, seizure treatment, and adjustment of a responsible medicine are different clinical decisions. Psychiatric treatment is matched to the diagnosed illness, associated symptoms, and preferences.
An interdisciplinary review and consensus paper recommends openly asking about hallucinations, addressing associated distress, and reviewing vision, cognition, physical health, and contributing medications. This is especially useful because many people fear that disclosing a visual experience will automatically lead to a psychiatric label.
When are antipsychotic medications appropriate?
Antipsychotic medications are sometimes used for clinically significant psychotic symptoms, but a visual hallucination alone is not a general indication. In dementia, treatment decisions require particular caution because serious adverse effects are possible. NICE NG97 advises assessing causes of distress, providing psychosocial and environmental care, and restricting antipsychotics to specified situations of risk or severe distress. It warns about severe sensitivity reactions in dementia with Lewy bodies and Parkinson's disease dementia.
The prescribing clinician considers the specific condition, likely benefit, risks, other medicines, medical history, and monitoring. Any decision about stopping or changing antipsychotics or medicines for Parkinson's disease should be made with the treating team. In a psychiatric disorder, psychological and psychosocial interventions may also be appropriate, but treatment plans vary by diagnosis.
What to Do If You Are Seeing Things Others Do Not See
First assess immediate safety and associated symptoms. Sudden confusion, collapse, seizure, stroke-like changes, severe illness, or imminent risk of harm requires emergency services. When the person is alert and safe but the experience is new or unexplained, seek prompt medical advice rather than trying to identify the diagnosis from the visual content alone.
If the episode is brief and the person remains oriented, move to a well-lit and safe area, sit down if balance is uncertain, and record the experience for a clinician. Avoid driving or operating machinery when vision or awareness is disturbed. If vision is impaired, check that prescribed glasses or visual aids are available. Avoid alcohol or nonprescribed intoxicants, and discuss medication concerns with a clinician. These steps help reduce immediate risk while the cause is evaluated; they do not replace treatment.
For a recurrent, previously assessed phenomenon such as Charles Bonnet syndrome, some people find that changing lighting, shifting gaze, blinking, focusing on real objects, and receiving an explanation make the episodes less disturbing. The effectiveness of coping methods varies and cannot be guaranteed. Persistent distress merits follow-up with the relevant medical professional.
How to Respond When a Family Member Reports Visual Hallucinations
Ask calmly what the person is seeing and whether they feel frightened or unsafe. You can acknowledge that the experience seems vivid without agreeing that the object is physically present. A simple response such as 'I understand you're seeing something, and I'm here with you' maintains dignity while avoiding arguments about perception.
Look for any departure from the person's usual level of alertness, attention, speech, movement, fever, or physical function. If the change is sudden, seek urgent assessment. Bring observations about the timing and current medications to the care team. If the person has chronic vision loss and remains otherwise clear, arrange an appropriate eye and medical evaluation rather than assuming the experience is psychiatric.
Avoid shaming, mocking, forceful confrontation, or automatic reassurance that there is 'nothing wrong.' The distress can be substantial even when the experience has a treatable or nonpsychiatric explanation. Education, a safe environment, and suitable clinical evaluation can support both the individual and their family.
Visual Hallucinations in Older Adults
In older adults, the main clinical considerations include delirium, eye disease, Parkinson's disease, dementia with Lewy bodies, medication burden, sleep disruption, and the interaction of several factors. The sudden appearance of images with new inattention or confusion is particularly urgent. A slower history of recurrent formed images with cognitive fluctuation, changes in movement, or dream-enactment behavior may lead the clinician to evaluate possible Lewy body disease. Long-standing low vision with otherwise preserved cognition may suggest a vision-related phenomenon. None of these patterns is sufficient alone to establish a diagnosis.
The NICE dementia guideline advises investigating reversible causes of cognitive symptoms and being alert to inappropriate anticholinergic medication burden. It also explains why antipsychotic medications require specialized risk assessment in dementia. The 2020 interdisciplinary review provides a broader model for managing hallucinations across older adult eye and brain disorders.
Can Anxiety or Stress Cause Visual Hallucinations?
Stress, disrupted sleep, grief, and high physiological arousal can affect perception, but a report of visual hallucinations should be assessed on its own clinical merits. A person with anxiety might misinterpret a shadow, notice normal visual phenomena more intensely, or describe a sleep-transition image. A fully formed visual hallucination is a reason to look beyond a generic explanation of stress, especially if it is new, recurrent, or accompanied by neurological or medical changes.
Anxiety about the experience can itself become significant. Someone may fear a severe mental illness or stop describing the phenomenon because of embarrassment. Reassurance is most appropriate after an adequate assessment and a clear discussion of which cause is suspected and what would warrant reevaluation.
Do Visual Hallucinations Always Mean Schizophrenia?
No. Visual hallucinations occur across neurological, ophthalmological, medical, sleep-related, substance-related, and psychiatric contexts. Schizophrenia is a clinical disorder defined through a wider set of symptoms, their duration, associated functioning, and diagnostic assessment; one visual experience cannot establish it. The NIMH publication on psychosis explains that psychotic symptoms may appear in many conditions and that some people who experience psychosis are never diagnosed with schizophrenia.
The English Hub's article on hallucinations across all sensory modalities covers the broader terminology and assessment, while this article concentrates on causes of seeing images and on medically important warning signs.
Frequently Asked Questions
Can visual hallucinations happen with your eyes open?
Yes. Visual hallucinations may be experienced with eyes open in ordinary surroundings. Others happen in darkness, with eyes closed, or around sleep transitions. Eye position alone does not determine the medical cause.
Why am I seeing people or animals who are not there?
Formed images of people or animals occur in several conditions, including Charles Bonnet syndrome associated with low vision and disorders such as Parkinson's disease or dementia with Lewy bodies. Other neurological and medical conditions remain possible. The clinical context, cognitive status, vision, timing, and medication history determine what needs evaluation. Weil and Lees review this differential.
Can someone have visual hallucinations and know they are not real?
Yes. Preserved insight is common in some vision-related phenomena and can appear in other situations. Insight may vary over time. It helps guide assessment but does not by itself confirm Charles Bonnet syndrome or rule out significant disease.
Can visual hallucinations be caused by a urinary tract infection?
An acute infection can contribute to delirium, especially in vulnerable people, and delirium can involve hallucinations. However, a urinary symptom, a positive urine test, or a hallucination by itself does not prove that a urinary infection is causing delirium. Clinicians evaluate the full presentation and other potential triggers rather than assigning causality from one finding. See NICE recommendations on delirium.
Are flashes of light the same as visual hallucinations?
Flashes can have ocular or neurological causes, including migraine aura or retinal problems. New flashes with floaters, a shadow or curtain, or sudden visual loss need urgent eye assessment. Flashing patterns that are familiar parts of previously diagnosed migraine still require reevaluation if their pattern or associated symptoms change.
Can lack of sleep cause visual hallucinations?
Sleep deprivation and sleep-transition phenomena can contribute to unusual perceptions. The relationship is not a reason to dismiss unexplained daytime hallucinations, especially when the person has confusion, a new medication, or medical symptoms. A clinician may evaluate sleep alongside other possible causes.
Is brain imaging needed for every visual hallucination?
No single investigation is required for everyone. Clinicians decide whether imaging, electroencephalography, blood tests, eye examination, or psychiatric evaluation is appropriate from the history, examination, and risk signs. Sudden focal neurological symptoms, a suspected seizure, or another structural concern may justify more urgent neurological tests.
Do visual hallucinations go away?
Their course depends on the cause. Some resolve when a medical trigger is treated or a medication is appropriately adjusted. Others recur as part of chronic eye or neurological conditions and can become less distressing with explanation, environmental support, and condition-specific treatment. Individual outcome cannot be inferred from the image content alone.
When should I contact a doctor if the hallucination has stopped?
A first unexplained visual hallucination deserves medical discussion even if it has ended. Seek emergency care for any associated sudden neurological signs, confusion, severe illness, or unsafe behavior. If the person is now stable and fully oriented, arrange timely medical or eye assessment according to the symptoms, age, medical history, and recurrence.
Related Articles
Hallucinations: Types, Causes, and Clinical Assessment — the broader sensory symptom and its clinical evaluation.
Psychosis Due to a Medical Condition: Causes and Evaluation — medical causes of psychotic symptoms and differential assessment.
Psychosis: Symptoms, Causes, Types, and When to Seek Help — clinical syndrome, warning signs, and care pathways.
Schizophrenia: Symptoms, Causes, Diagnosis, Treatment, and Recovery — the distinct psychiatric disorder and evidence-based care.