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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Delirium recognition, causes and prevention

Psychiatry · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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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.

Synopsis

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 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.
  • 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.

    • Key red flags

    Reduced consciousness, airway risk, oxygen desaturation, hypotension, severe temperature abnormality or hypoglycaemia needs resuscitation before formal cognitive testing.

    New focal neurology, thunderclap headache, 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

    Investigation priorities

    01
    ABCDE and bedside glucoseFirst step

    Detect hypoxia, shock, hypoglycaemia, temperature disturbance and reduced consciousness requiring immediate treatment.

    Management branches

    New acute changeStabilise and diagnose in parallel

    Attention, awareness, arousal, cognition or behaviour changes acutely or fluctuates from baseline.

    1. Perform ABCDE, glucose and focused neurological assessment, treat immediate abnormalities and obtain collateral baseline and onset.
    2. Use the 4AT, or CAM-ICU or ICDSC in critical care or recovery, while identifying physical, medicine, withdrawal and environmental contributors.
    3. Start cause-specific treatment and supportive delirium care immediately; escalate for sepsis, stroke, seizure, trauma, poisoning or organ failure as indicated.

    Key medicines

    Oral haloperidol for exceptional acute delirium distressFor 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.
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    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.
    • MHRA haloperidol risks in elderly deliriumContraindications, ECG and electrolyte checks, neurological monitoring and minimum-dose advice.
    • SIGN delirium risk reduction and managementScottish evidence-based recognition, prevention, assessment and management guidance.
    • NICE NG97 dementia recommendationsDistinguishing delirium, dementia and delirium superimposed on dementia and treating delirium first.
    • Haloperidol oral solution SmPCCurrent UK licensed dosing, contraindications and safety information for oral haloperidol.

    Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

    Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
    in these conditions.