Seeing something that isn’t there can be frightening, confusing, or both. Visual hallucinations happen when the brain creates an image that has no source in the outside world. They can result from many different causes, including certain medical conditions, medications, sleep problems, and substance use. Some causes are serious and need urgent care, while others are manageable with treatment.
What Are Visual Hallucinations?
A visual hallucination is the experience of seeing something that is not actually present. The person genuinely perceives it — it is not imagination, a dream, or a metaphor.
Doctors distinguish hallucinations from illusions. An illusion is a misreading of something real, like mistaking a coat rack for a person in dim light. A hallucination has no real object behind it at all.
Visual hallucinations can be simple or complex:
- Simple — flashing lights, geometric shapes, colors, or zigzag lines
- Complex — people, animals, faces, scenes, or full figures
They can appear briefly or last for extended periods. Some people see them only in low light or when falling asleep. Others experience them throughout the day.
Visual hallucinations are less common than auditory ones. Hearing voices is the most frequent type of hallucination in conditions like schizophrenia. Visual hallucinations more often point toward neurological, medical, or medication-related causes.
What Causes Visual Hallucinations And When To Worry?
The cause determines whether a visual hallucination is a minor issue or a medical emergency. Understanding the underlying reason is the first step toward knowing how concerned to be.
Neurological Conditions
Conditions affecting the brain are among the most well-established causes of visual hallucinations.
Migraine with aura can produce visual disturbances, including flashing lights, zigzag patterns, or blind spots. These are technically aura symptoms rather than true hallucinations, but the distinction can blur. Aura typically develops gradually and resolves within about an hour.
Epilepsy involving the occipital lobe — the brain’s visual processing area — can trigger visual hallucinations. These tend to be brief, often colorful or geometric, and may occur alongside other seizure symptoms.
Parkinson’s disease and Lewy body dementia are strongly linked to visual hallucinations. Research indicates that a significant proportion of people with Parkinson’s disease experience them at some point, particularly as the disease progresses. The hallucinations are often detailed and may involve people or animals. They frequently occur in the evening or in low light.
Charles Bonnet syndrome causes vivid visual hallucinations in people who have lost significant vision. The brain, deprived of normal visual input, generates images on its own. People with this syndrome are typically aware the images are not real, which distinguishes it from psychotic disorders.
Medications
Many prescription medications can cause visual hallucinations as a side effect. This is more common in older adults, who often take multiple medications.
Drugs that can trigger visual hallucinations include:
- Some Parkinson’s disease medications (dopamine agonists)
- Certain antidepressants and antipsychotics
- Some sleep aids and sedatives
- Opioid pain medications
- Some antibiotics and antivirals
- Steroids
If hallucinations begin after starting or changing a medication, that timing matters. A doctor should review all medications carefully.
Substance Use and Withdrawal
Alcohol withdrawal can cause visual hallucinations, often within the first day or two after heavy drinking stops. This is a medical emergency that requires immediate treatment.
Hallucinogenic drugs like LSD and psilocybin reliably produce visual hallucinations. Some people experience persistent visual disturbances after using hallucinogens, a condition sometimes called hallucinogen persisting perception disorder.
Psychiatric Conditions
Schizophrenia and related disorders can involve visual hallucinations, though auditory hallucinations are more typical. When visual hallucinations occur in schizophrenia, they often accompany other symptoms like delusions or disorganized thinking.
Severe depression with psychotic features and bipolar disorder can also involve visual hallucinations in some cases.
Other Medical Causes
Several other conditions can produce visual hallucinations:
- Delirium — a sudden state of confusion that often includes hallucinations, commonly triggered by infection, surgery, or medication changes
- High fever — especially in children, can cause hallucinations
- Severe dehydration or electrolyte imbalances
- Liver or kidney failure — when toxins build up in the blood
- Brain tumors — depending on location
- Stroke — particularly affecting visual pathways
- Dementia — various forms can involve hallucinations, especially in later stages
Sleep-Related Causes
Hypnagogic hallucinations occur as a person is falling asleep. Hypnopompic hallucinations happen upon waking. Both are relatively common and generally not a sign of serious illness.
Sleep deprivation can also trigger visual disturbances. Narcolepsy is associated with vivid hallucinations at sleep boundaries.
When Should You Worry About Visual Hallucinations?
Visual hallucinations always deserve medical attention, but some situations require emergency care.
Seek immediate medical help if hallucinations:
- Begin suddenly and are new
- Come with confusion, fever, or a severe headache
- Follow a head injury
- Occur alongside weakness, numbness, or difficulty speaking
- Happen during alcohol or drug withdrawal
- Involve the person being unable to recognize where they are or what is happening
Contact a doctor soon if hallucinations:
- Start after a medication change
- Occur repeatedly over days or weeks
- Disturb sleep or daily functioning
- Frighten the person or their family
The key distinction is between hallucinations that are stable and familiar versus those that are new, sudden, or accompanied by other neurological symptoms. New symptoms always warrant evaluation.
How Are Visual Hallucinations Diagnosed?
Diagnosis starts with a detailed history. A doctor will ask what the person sees, when it happens, how long it lasts, and whether anything triggers it.
They will also review medications, alcohol and drug use, sleep patterns, and any other medical conditions.
Depending on the suspected cause, testing may include:
- Blood tests to check for infection, electrolyte imbalances, or organ problems
- Brain imaging (MRI or CT scan)
- Electroencephalogram (EEG) if seizures are suspected
- Eye examination if vision loss is involved
- Psychiatric evaluation if a mental health condition is possible
There is no single test for visual hallucinations. The goal is to identify the underlying cause.
What Treatment Options Exist?
Treatment depends entirely on the cause. There is no one-size-fits-all approach.
If a medication is responsible, adjusting or switching it may resolve the hallucinations. This should only be done under medical supervision.
For Parkinson’s disease and Lewy body dementia, doctors may adjust Parkinson’s medications or prescribe certain antipsychotics that are safer for these conditions. Not all antipsychotics are appropriate — some can worsen symptoms in Lewy body dementia.
For epilepsy, anti-seizure medications may reduce or eliminate visual hallucinations.
For Charles Bonnet syndrome, there is no established cure. Some people find that improving lighting or staying mentally and socially active helps reduce episodes. Research on treatment options is ongoing.
For psychiatric conditions, antipsychotic medications and therapy may help.
For alcohol withdrawal, immediate medical treatment is essential. This is not something to manage at home.
In all cases, the underlying cause must be addressed. Treating the symptom alone rarely works.
What Should You Do If You or Someone Else Sees Things That Aren’t There?
Stay calm and take it seriously. Do not dismiss the experience or assume it is imaginary.
If the person is confused, feverish, or showing other neurological symptoms, seek emergency care.
If the hallucinations are new but the person is otherwise stable, schedule a medical appointment soon. Bring a list of all medications and note when the hallucinations started.
If you are with someone who is hallucinating, avoid arguing about whether what they see is real. Instead, focus on keeping them safe and comfortable until they can be evaluated.
Visual hallucinations are a symptom, not a diagnosis. They can stem from many causes, some benign and some serious. The only way to know which is to get a proper medical evaluation.
Frequently Asked Questions
Can stress cause visual hallucinations?
Severe stress or sleep deprivation can contribute to visual disturbances, but true visual hallucinations from stress alone are uncommon. If hallucinations occur, a medical evaluation is needed to rule out other causes.
Are visual hallucinations a sign of mental illness?
Not necessarily. Many medical conditions, medications, and neurological disorders can cause visual hallucinations. Mental illness is one possible cause but not the most common one for visual hallucinations specifically.
When should I go to the emergency room for visual hallucinations?
Go to the emergency room if hallucinations start suddenly, come with confusion, fever, severe headache, or follow a head injury. Alcohol or drug withdrawal with hallucinations is also a medical emergency.
Can dehydration cause visual hallucinations?
Severe dehydration, especially when it causes electrolyte imbalances, can lead to confusion and hallucinations. This is more likely in older adults or people who are already ill.
