Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Delirium recognition, causes and prevention
Psychiatry · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Acute cognitive change is a medical emergency until explained
New inattention or altered arousal with hypoxia, hypoglycaemia, sepsis, shock, stroke signs, seizure, head injury, poisoning, urinary retention, severe pain or withdrawal requires immediate medical assessment even when the person is quiet rather than agitated.
Action: Assess ABCDE, glucose, oxygenation and observations; identify the time course and baseline from someone who knows the person; treat immediately reversible threats; review medicines and withdrawal; and investigate likely precipitants in parallel. Provide close observation and a calm familiar environment, escalating to acute medical or critical care according to physiology rather than behavioural intensity.
Overview
Detect delirium including the easily missed hypoactive form, treat acute physiological threats and multiple precipitants promptly, prevent avoidable episodes with tailored multicomponent care, and reserve medication for exceptional severe distress or danger.
Delirium develops over hours or days and fluctuates during the day. The defining bedside problem is impaired attention with altered awareness or cognition, not simply memory loss. Ask the person to follow a short conversation, state months backwards or respond to a simple command, but interpret performance alongside arousal, hearing, language and prior ability. Obtain a dated baseline from someone who knows them: a person with dementia can still have delirium when their attention, alertness, function or behaviour changes abruptly.
Motor activity does not determine severity. Hyperactive delirium may bring agitation, fear, hallucinations and attempts to leave, whereas hypoactive delirium produces drowsiness, withdrawal, slow answers, reduced movement and poor intake. The latter is easily mistaken for depression, tiredness or cooperative behaviour. Mixed delirium shifts between states. Document fluctuation and repeat assessment because one lucid encounter cannot exclude a syndrome that was obvious overnight.
Practice
Two practice questions
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PsychiatryOriginal SBA
Choosing a delirium tool
An 82-year-old medical inpatient becomes inattentive and drowsy over one day, with fluctuation reported by nursing staff. The patient is not in critical care or postoperative recovery. Which assessment tool does NICE recommend when delirium indicators are present?
Sources and review status5 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NICE CG103 delirium recommendationsCurrent recognition tools, prevention package, cause treatment, de-escalation and brief haloperidol principles.
NICE advises using the 4AT when indicators of delirium are identified in hospital or long-term care. In critical care or recovery after surgery, use CAM-ICU or the Intensive Care Delirium Screening Checklist instead. A positive tool supports but does not replace diagnosis by a practitioner with relevant expertise. Cognitive screening alone cannot reliably separate delirium, dementia and delirium superimposed on dementia. When uncertainty persists, treat delirium first because delay leaves acute causes untreated.
Immediate assessment follows physiology. Perform ABCDE, bedside glucose, pulse oximetry, temperature, cardiovascular and neurological examination. Clarify intake, urine, stool, pain, falls, operations, catheters, sleep, alcohol and drug use. Review every medicine and recent start, stop or dose change, including anticholinergic drugs, opioids, sedatives, corticosteroids and dopaminergic treatment. Investigation is targeted by the story but commonly includes blood count, renal and electrolyte profile, liver and inflammatory markers, urinalysis only when urinary infection is clinically plausible, ECG and appropriate chest or other imaging.
Delirium is often multifactorial. Pneumonia may coexist with dehydration, undertreated pain and a newly prescribed sedative. Treating one positive urine result while ignoring hypoxia, retention or withdrawal is unsafe. Avoid diagnosing urinary infection from asymptomatic bacteriuria alone. Check constipation and bladder retention directly, inspect for injury and pressure damage, and consider medication toxicity when renal function changes. New focal signs, seizure, head injury, meningism or an unexplained reduced level of consciousness changes the urgency and test selection.
Treatment combines cause correction with supportive brain care. Reorient using clocks, daylight, names and repeated simple explanations; ensure glasses and hearing aids work; involve familiar people; maintain hydration and nutrition; treat pain while avoiding avoidable sedation; mobilise safely; remove unnecessary lines; and protect uninterrupted sleep without depriving daytime activity. Do not move the person between rooms or wards unless necessary. The same elements form a tailored multicomponent prevention package for people at risk.
Distress needs interpretation before suppression. Fear may arise from pain, urinary retention, an unfamiliar carer, misheard speech or frightening hallucinations. Approach slowly, use one speaker, reduce noise and crowding, acknowledge emotion and offer a familiar supporter. Physical restraint can intensify delirium and injury and requires lawful, proportionate, least-restrictive decision-making. Constant or enhanced observation may be safer than sedation, but observation must include comfort, hydration, toileting and reassessment rather than surveillance alone.
If a person is severely distressed or poses a risk to themselves or others and de-escalation is ineffective or inappropriate, NICE says to consider short-term haloperidol, usually for one week or less, at the lowest clinically appropriate dose with cautious titration. This is an exception, not treatment of the underlying delirium. MHRA advises baseline ECG and correction of electrolyte disturbance, repeated cardiac and electrolyte monitoring as appropriate, and active surveillance for extrapyramidal effects including dysphagia. Parkinson's disease, dementia with Lewy bodies and important QT risks may contraindicate it.
Recovery can lag behind correction of the trigger. Explain the diagnosis to the person and family, record it for future admissions, reassess cognition and function, and review whether new support is needed. Persistent symptoms should trigger another search for untreated contributors, medicine effects or previously unrecognised cognitive disorder. A later dementia assessment should use the recovered baseline rather than cognitive scores obtained in the acute delirium alone.
Key points
Delirium is an acute and fluctuating disturbance of attention, awareness and cognition caused by physiological disturbance; it is not a synonym for chronic confusion.
Establish hours-to-days onset and fluctuation against the person's own baseline, using family, carers, staff and records when the patient cannot provide a reliable timeline.
NICE recommends the 4AT when indicators are present; use CAM-ICU or the Intensive Care Delirium Screening Checklist in critical care or postoperative recovery.
Arousal may be hyperactive, hypoactive or mixed. Quiet withdrawal, slow responses and reduced mobility are commonly missed and do not imply mild disease.
Search for several contributors at once: infection, hypoxia, dehydration, pain, constipation or retention, metabolic disturbance, organ failure, medicines, intoxication, withdrawal, sleep disruption and unfamiliar surroundings.
If delirium and dementia cannot be distinguished, NICE advises treating delirium first while continuing a careful assessment of baseline cognition.
Treat causes and provide orientation, hydration, mobility, pain relief, sensory aids, sleep protection, nutrition and medication rationalisation; avoid unnecessary moves and restraints.
For distress or danger, try verbal and non-verbal de-escalation first. Medication is not a routine response to wandering, calling out or staff workload.
Aetiology
01
Acute physiological insult
Infection, hypoxia, metabolic disturbance, organ failure, injury or surgery disrupts vulnerable brain function and produces an acute fluctuating syndrome.
02
Medicine and withdrawal effects
Anticholinergic exposure, sedatives, opioids, drug accumulation, intoxication and abrupt alcohol or medicine withdrawal can precipitate delirium.
03
Reduced cerebral resilience
Dementia, advanced age, frailty, sensory loss and severe illness lower the physiological disturbance needed to trigger acute brain dysfunction.
04
Environmental amplification
Sleep loss, immobility, unfamiliar surroundings, sensory deprivation, restraints and repeated moves add modifiable stress to existing medical precipitants.
Pathophysiology
1
Network integration failure
Systemic illness disrupts distributed attention and arousal networks, producing unstable awareness, cognition and behavioural organisation across short periods.
2
Neurotransmitter imbalance
Altered cholinergic, dopaminergic and stress signalling contributes to inattention, perceptual disturbance and motor changes without one universal biochemical pathway.
3
Inflammatory and metabolic stress
Cytokines, impaired oxygen delivery, glucose disturbance and organ dysfunction alter neuronal function in a brain with limited reserve.
4
Circadian disorganisation
Illness, light disruption, nocturnal care and sedatives disturb sleep-wake regulation, worsening fluctuation and reducing restorative daytime engagement.
Clinical features and red flags
Acute attentional change
Difficulty sustaining or shifting attention emerges over hours or days and differs clearly from the person's usual cognitive performance.
Fluctuating arousal
Alertness, engagement and cognitive performance vary across the day, with lucid intervals that can falsely reassure an isolated assessor.
Hyperactive pattern
Restlessness, fear, hallucinations, calling out or unsafe movement may be conspicuous but remain expressions of physiological brain dysfunction.
Hypoactive pattern
Withdrawal, slowed answers, reduced movement, drowsiness and poor intake are easily overlooked despite comparable underlying medical danger.
Mixed motor pattern
The same person alternates between agitation and reduced responsiveness as precipitants, environment, sleep and medicines change.
Delirium on dementia
An abrupt decline in attention, arousal or function occurs on top of established chronic cognitive impairment and requires acute treatment.
Red flags requiring action
Reduced consciousness, airway risk, oxygen desaturation, hypotension, severe temperature abnormality or hypoglycaemia needs resuscitation before formal cognitive testing.
New focal neurology, thunderclap headache
Investigations
01ABCDE and bedside glucoseFirst step
Why
Detect hypoxia, shock, hypoglycaemia, temperature disturbance and reduced consciousness requiring immediate treatment.
Structure assessment of alertness, orientation, attention and acute change or fluctuation when delirium indicators appear.
Interpretation and limitations
A trained clinician makes the diagnosis; language, sensory loss and baseline cognition affect performance and a single score is not the whole assessment.
03Collateral timeline
Why
Establish baseline cognition and function, exact onset, fluctuation, recent illness, procedures and medicine changes.
Interpretation and limitations
Hours-to-days change supports delirium, while collateral uncertainty increases the need for repeated observation rather than retrospective certainty.
04Targeted physical examination
Why
Identify infection, neurological disease, pain, injury, dehydration, constipation, retention and organ decompensation.
Interpretation and limitations
Select tests from positive findings and risk; several mild contributors may together explain a severe syndrome.
Differential diagnosis
01
Dementia without delirium
A gradual progressive decline lacks the abrupt attentional and arousal fluctuation of delirium, although both conditions commonly coexist.
02
Depression
Low motivation, slowed answers and poor concentration can mimic hypoactive delirium but usually lack acute fluctuating consciousness and physiological cause.
03
Primary psychosis or mania
Hallucinations and agitation may occur without global inattention, yet late or abrupt onset demands medical and substance assessment first.
04
Aphasia or sensory impairment
Language, hearing and vision barriers can produce apparent disorientation unless communication is adapted and baseline ability is established.
05
Non-convulsive seizure
Episodic unresponsiveness, subtle motor signs or unexplained persistent altered awareness may require urgent neurological assessment and electroencephalography.
Management
01New acute changeStabilise and diagnose in parallelFirst stepAttention, awareness, arousal, cognition or behaviour changes acutely or fluctuates from baseline.+
1Perform ABCDE, glucose and focused neurological assessment, treat immediate abnormalities and obtain collateral baseline and onset.
2Use the 4AT, or CAM-ICU or ICDSC in critical care or recovery, while identifying physical, medicine, withdrawal and environmental contributors.
3EscalationStart cause-specific treatment and supportive delirium care immediately; escalate for sepsis, stroke, seizure, trauma, poisoning or organ failure as indicated.
02Distress or dangerDe-escalate before exceptional medicationEscalationFear, hallucinations, agitation or unsafe behaviour causes severe distress or risk during delirium.+
Complications
01
Falls and physical injury
Impaired attention, unsafe mobility, hypotension, lines and sedating medicines combine to increase falls, restraint injury and pressure damage.
02
Aspiration and malnutrition
Reduced arousal, dysphagia, poor intake and extrapyramidal effects can cause dehydration, aspiration pneumonia and prolonged functional decline.
03
Prolonged cognitive loss
Recovery may remain incomplete for weeks or months, particularly after severe illness or in people with underlying cognitive impairment.
04
Institutional and mortality risk
Delirium is associated with longer admission, loss of independence, care-home placement and death, reflecting serious acute vulnerability.
05
Traumatic care experience
Frightening hallucinations, restraint, repeated moves and poor explanation can leave lasting distress for the person, family and staff.
Monitoring and follow-up
Repeat attention, arousal, 4AT features and functional observation across shifts because delirium fluctuates and one normal interaction does not prove recovery.
Track oxygenation, hydration, intake, pain, bowel and bladder function, mobility, sleep and each identified physiological precipitant.
Review medicines every day for new exposure, withdrawal, anticholinergic burden, renal accumulation and whether temporary changes can be reversed.
If haloperidol is used, record the target distress or danger, dose, ECG and electrolyte assessment, benefit, adverse effects and planned stop date.
After apparent recovery, ask the person and family about residual cognitive or functional change and arrange follow-up for persistent impairment.
Record delirium prominently in transfer and discharge documents, including causes, effective adjustments and medicines that caused or worsened it.
Special situations
Quiet delirium is dangerous
Hypoactive withdrawal attracts less attention than agitation yet may reflect severe infection, dehydration, respiratory failure or medicine toxicity.
Lucidity does not exclude
Fluctuation permits a coherent morning conversation after severe overnight inattention, so collateral and repeated observation remain essential.
Several small causes combine
Constipation, pain, sleep loss and a sedative may jointly precipitate delirium without one dramatic laboratory abnormality.
Tools support diagnosis
The 4AT structures recognition but does not replace clinical expertise, physiological assessment or an explanation of the acute change.
Sedation can hide deterioration
Reduced movement after antipsychotic treatment may represent adverse effects or worsening consciousness rather than successful delirium treatment.
Common pitfalls
01
Calling every confused older person demented without establishing acute onset, fluctuation, attention and baseline function.
02
Missing hypoactive delirium because the person is quiet, sleepy or not interfering with ward routines.
03
Treating a positive urine dipstick or culture as the sole explanation without compatible symptoms and a broader cause search.
04
Using a cognitive score alone to distinguish delirium from dementia or delaying treatment until diagnostic certainty is perfect.
05
Prescribing haloperidol before de-escalation, ECG and electrolyte review or despite Parkinson's disease, Lewy-body dementia or QT contraindications.
06
Using restraint, ward moves, sleep interruption or unnecessary catheters in ways that amplify fear and disorientation.
07
Failing to document delirium and reassess residual cognition after the acute illness improves.
JurisdictionUnited Kingdom
NICE permits short-term haloperidol, usually one week or less, only when de-escalation is ineffective or inappropriate; use the lowest dose and heed MHRA cardiac and neurological cautions.
Prevention starts within twenty-four hours for at-risk hospital or long-term-care patients through an individual multicomponent package rather than a prophylactic sedative.
, recent head trauma, seizure or meningism requires an urgent neurological and medical pathway rather than a diagnosis of uncomplicated delirium.
Marked autonomic disturbance, tremor, hallucinations and agitation after stopping alcohol or sedative medication can indicate dangerous withdrawal requiring a specific monitored regimen.
Immobility, withdrawal, slow responses, reduced appetite or new drowsiness may represent hypoactive delirium and carry serious illness despite creating little disruption.
Rigidity, fever, autonomic instability, dysphagia or reduced consciousness after an antipsychotic can signal a severe drug reaction and needs urgent cessation and medical review.
A person with Parkinson's disease or dementia with Lewy bodies is especially vulnerable to severe neurological effects from haloperidol, which is contraindicated in these conditions.
05
Laboratory and ECG assessment
Why
Evaluate blood count, renal, metabolic, inflammatory and medication-related contributors and cardiac treatment risk.
Interpretation and limitations
Results must be interpreted clinically; asymptomatic bacteriuria and incidental abnormalities should not end the search for causes.
06Directed imaging or specialist testing
Why
Investigate focal neurology, trauma, seizure, chest disease, abdominal pathology, poisoning or other specific concern.
Interpretation and limitations
Routine brain imaging is not required for every delirium, but red flags lower the threshold for urgent targeted investigation.
1
EscalationCheck pain, hypoxia, retention, hunger, communication, sensory impairment and immediate environmental triggers, then use calm verbal and non-verbal de-escalation.
2Increase skilled observation and familiar support and choose the least restrictive lawful safety measure rather than reflexive restraint.
3Only if these measures are ineffective or inappropriate, consider brief low-dose haloperidol after contraindication, ECG and electrolyte review, with frequent reassessment and an early stop plan.
03PreventionDeliver a tailored multicomponent packageA hospital or long-term-care patient has delirium risk such as older age, cognitive impairment, severe illness or hip fracture.+
2Correct the person's identified risks through trained multidisciplinary care, familiar staff and avoidance of unnecessary room or ward moves.
3Observe at least daily for new indicators, document change and begin diagnostic assessment promptly rather than waiting for agitation.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
A brief rescue option only for delirium with severe distress or risk after verbal and non-verbal de-escalation is ineffective or inappropriate; it does not treat the precipitating cause.
Oral haloperidol for exceptional acute delirium distress
For an older person when non-drug measures have failed and no contraindication exists: start oral haloperidol 0.5 mg daily, titrate cautiously to response, and do not exceed 5 mg daily; NICE usually limits delirium treatment to 1 week or less.
Avoid in Parkinson's disease, dementia with Lewy bodies, known QT prolongation, uncorrected hypokalaemia and relevant QT-prolonging combinations. Obtain baseline ECG and correct electrolytes; monitor rhythm, blood pressure, extrapyramidal effects, swallowing, sedation and aspiration risk, stopping as soon as feasible.