01 · Overview
The short version
A hallucination is a symptom, not a diagnosis
Hearing, seeing, feeling, smelling, or tasting something that is not really there can happen for many reasons. The context matters more than the symptom alone.
Sudden confusion changes the level of concern
Hallucinations that start suddenly with confusion, poor attention, sleep-wake changes, dehydration, fever, or a new medicine can fit delirium and need prompt medical evaluation.
Timing can point to different causes
Hallucinations while falling asleep or waking up can be sleep-related. Hallucinations during full wakefulness, especially with memory or movement changes, raise more concern for medical, neurologic, or psychiatric causes.
Safety matters first
If hallucinations come with dangerous behavior, severe confusion, a seizure, stroke symptoms, overdose, or suicidal thoughts, emergency help is safer than waiting.
02 · Care guidance
When to get help
Emergency help
- Call 911 or go to the emergency department now if hallucinations come with severe confusion, trouble staying awake, seizure, stroke symptoms, chest pain, high fever, breathing trouble, a suspected overdose, or sudden dangerous behavior.
- Call 988 right away if hallucinations are linked to suicidal thoughts, self-harm, or a voice telling the person to hurt themselves or someone else.
Get advice promptly
- Contact a clinician promptly if hallucinations are new, getting worse, happening during full wakefulness, or occurring with memory problems, tremor, stiffness, major mood changes, or recent medicine or substance changes. If they start after alcohol or drug use changes, or come with confusion, fever, or dehydration, seek same-day urgent medical advice because delirium or withdrawal may be involved.
- Seek prompt evaluation if hallucinations happen with urinary symptoms, cough, dehydration, poor sleep, alcohol withdrawal, or a recent illness, because the trigger may be treatable.
If hallucinations are mild, brief, and clearly tied to falling asleep or waking up, schedule a non-urgent visit to review sleep, stress, medications, and overall health.
03 · Hallucinations
What a hallucination actually means
The symptom is real to the person, but it does not point to one single illness.
Hallucinations are false perceptions. A person may hear voices or music, see people or animals, feel insects crawling on the skin, or less often smell or taste something that is not there. The brain is creating a sensory experience without a matching outside source.
That can happen in psychotic disorders, but also in delirium, dementia, substance use or withdrawal, sleep-related states, and some neurologic problems. The same symptom can mean very different things in a teenager with no medical issues, an older adult after surgery, or someone who just started a new medicine.
- Auditory hallucinations affect hearing.
- Visual hallucinations affect sight.
- Tactile, smell, and taste hallucinations can also happen, but they are less common.
04 · Hallucinations
The causes clinicians think about first
The most likely explanations depend on age, timing, and whether there is confusion or a recent trigger.
Psychotic disorders can cause hallucinations, and schizophrenia is one example. Bipolar disorder can also include psychotic symptoms during severe mood episodes. These conditions usually fit a broader pattern of changes in thinking, mood, or behavior, not a single isolated episode.
Delirium is different. It starts suddenly, often changes over hours or days, and can include hallucinations plus confusion, poor attention, disorganized thinking, and sleep changes. Common triggers include infection, dehydration, electrolyte problems, hospitalization, pain, sleep deprivation, alcohol or drug intoxication or withdrawal, and medicines or medicine withdrawal.
In older adults, Lewy body dementia is an important neurologic cause to think about. It can cause visual hallucinations along with changes in attention, wakefulness, movement, and sleep. Brain infections, stroke, and tumors are less common but still important possibilities when symptoms are new or severe.
- Sudden confusion points toward delirium.
- Mood symptoms can point toward bipolar disorder.
- Visual hallucinations plus movement or sleep changes raise concern for Lewy body dementia in older adults.
06 · Hallucinations
Medicines, alcohol, and withdrawal
A full medicine and substance history is often the fastest way to find a treatable cause.
Alcohol intoxication and alcohol withdrawal can both cause hallucinations. Delirium tremens is a severe form of alcohol withdrawal and is a medical emergency. Other drugs can also trigger hallucinations, and some medicines can do the same as a side effect or after they are stopped suddenly.
The medication review has to include prescription drugs, over-the-counter products, sleep aids, pain medicines, antihistamines, cannabis products, and supplements. This matters because the cause may be a medicine effect, a withdrawal reaction, or a medicine interacting with dehydration, infection, or poor sleep.
People should not stop a prescribed medicine abruptly unless a clinician tells them to. Suddenly stopping some medicines can worsen symptoms or create a new problem.
- Bring every medication bottle or list to the visit.
- Mention recent dose changes, missed doses, and recent alcohol or drug changes.
- Do not assume a hallucination means the medicine is the only cause, but do not ignore the timing either.
07 · Hallucinations
How clinicians sort out the cause
The visit is usually about pattern recognition plus a focused medical check, not just naming the symptom.
A clinician usually asks when the hallucinations started, what they are like, how often they happen, whether they occur during sleep transitions or full wakefulness, and whether the person is confused or inattentive. Other questions focus on fever, headache, weakness, tremor, stiffness, mood changes, sleep loss, recent illness, and any new medicine or substance change.
The exam may include checking thinking, alertness, memory, and the nervous system. Depending on the situation, testing can include blood work, urine testing, and sometimes brain imaging. If delirium is suspected, the goal is to find the trigger quickly. If a neurologic condition is suspected, memory and movement testing may be part of the workup.
- Write down exact examples of what was seen or heard.
- Bring a caregiver or family member if memory or confusion is part of the problem.
- Tell the clinician about infections, dehydration, alcohol use, and all medicines.
08 · Hallucinations
When hallucinations are urgent
Sudden change, confusion, neurologic symptoms, or danger to self or others needs immediate action.
Hallucinations that start suddenly with confusion, poor attention, disorganized thinking, fever, dehydration, a new medicine, or recent hospitalization are especially concerning for delirium. Delirium can be temporary and treatable, but it often comes from an underlying medical problem that should not wait.
Emergency care is also needed if hallucinations come with stroke symptoms, seizure, trouble breathing, chest pain, suspected overdose, severe agitation, or a person who cannot stay awake. If the hallucination includes a command to self-harm or harm someone else, call 988 for mental health crisis support in the U.S. If there is immediate physical danger, call 911.
- Do not wait for a routine visit if the person is unsafe.
- Stay with the person if they are confused or acting on the hallucination.
- Treat sudden hallucinations plus confusion as an urgent medical problem.
09 · FAQ
Questions people ask
What if the person knows the hallucination is not real?
That can still matter. Insight does not rule out a medical, neurologic, or mental health cause. A person who recognizes the experience as unreal should still be evaluated if the episodes are new, frequent, distressing, linked to a medicine change, or affecting safety, sleep, or daily life.
Are visual hallucinations more serious than hearing voices?
Not always. The level of concern depends more on the setting than on the sense involved. Visual hallucinations in an older adult, especially with confusion or movement changes, can point toward delirium or Lewy body dementia, while hearing voices during a psychotic episode can also be serious and may need urgent care if safety is at risk.
Should family members argue with the person about the hallucination?
No. Arguing usually makes distress worse. It is better to stay calm, speak simply, lower noise, improve lighting, and focus on safety. If the person seems confused, feverish, severely sleepy, or dangerous to themselves or others, treat it as a medical emergency rather than trying to reason it away.
Can dehydration really be part of the problem?
Yes. Dehydration is listed as a common trigger for delirium, and delirium can include hallucinations. If hallucinations happen along with poor intake, vomiting, diarrhea, fever, or very little urination, that increases the need for prompt medical assessment.
What should I bring to the appointment?
Bring a complete medication list, including prescriptions, over-the-counter products, supplements, and any recent changes. It also helps to write down when the hallucinations happen, what they are like, whether they are linked to sleep or full wakefulness, and any changes in memory, movement, mood, sleep, fever, or substance use.
Can hallucinations go away on their own?
Sometimes, especially if they are tied to a sleep transition or a temporary trigger such as illness, dehydration, or a medicine effect. But new hallucinations should not be assumed to be harmless, because some causes need treatment before they improve.
10 · References
References and supporting evidence
These sources support the points identified below. Source checking is not clinical approval.
- S1: DeliriumMedlinePlus / U.S. National Library of Medicine
Explains that delirium starts suddenly and involves confusion and impaired thinking, which supports the article’s urgency and triage language for hallucinations with confusion or poor attention.
- S2: Psychotic DisordersMedlinePlus / U.S. National Library of Medicine
Explains what hallucinations are and supports the broad description that they can affect hearing, sight, or touch.
- S3: Lewy Body DementiaMedlinePlus / U.S. National Library of Medicine
Explains that Lewy body dementia can include visual hallucinations plus movement and sleep changes, which supports the article’s older-adult warning pattern.
General information, not a diagnosis. This guide is not a substitute for care from a qualified healthcare professional. For an emergency, call 911 in the US or your local emergency number. Illustrations are conceptual and are not diagnostic images.