Delirium Chapter

Presenting complaints

  • Staff may request help because the patient is confused or agitated.
  • Patients may appear uncooperative or fearful.
  • Delirium may occur in patients hospitalised for physical conditions.

Diagnostic features

Acute onset, usually over hours or days, of:

  • confusion (patient appears disoriented and struggles to understand surroundings) and
  • clouded thinking or awareness.

Often accompanied by:

  • poor memory
  • agitation
  • emotional upset
  • loss of orientation
  • wandering attention
  • hearing voices
  • withdrawal from others
  • visions or illusions
  • suspiciousness
  • disturbed sleep (reversal of sleep pattern) and
  • autonomic features, eg sweating, tachycardia.

Symptoms often develop rapidly and may change from hour to hour.

Delirium may occur in patients with previously normal mental function or in those with dementia. Milder stresses (eg medication and mild infections) may cause delirium in older patients or in those with dementia.

Differential diagnosis

Identify and correct the possible underlying physical causes of the delirium, such as:

  • alcohol intoxication or withdrawal
  • drug intoxication, overdose or withdrawal (including prescribed drugs)
  • infection
  • metabolic changes, eg liver disease, dehydration, hypoglycaemia
  • head trauma
  • hypoxia or
  • epilepsy.

If symptoms persist, delusions and disordered thinking predominate, and no physical cause is identified (see Acute psychotic disorders).

Essential information

Essential information for the patient and primary support group

Strange behaviour or speech and confusion can be symptoms of a medical illness.

Advice and support to the patient and primary support group (ref 1)

  • Take measures to prevent the patient from harming him/herself or others, eg remove unsafe objects, restrain if necessary but use the minimum amount of restraint required and take extra care to ensure no physical harm to the patient (see Managing aggression and violence).
  • Supportive contact with familiar people can reduce confusion.
  • Provide frequent reminders of time and place to reduce confusion.
  • A transfer to hospital may be required because of agitation or because of the physical illness that is causing delirium. There is an appreciable mortality rate with delirium. Patients may need to be admitted to a medical ward in order to diagnose and treat the underlying disorder. In an emergency, where there is risk to life and safety, a medically ill patient may be taken to a general hospital for treatment under common law. In such a case, a medical doctor may make this decision without involvement of a psychiatrist (see Emergency treatment under common law).


1 Rabins PV. Psychosocial and management aspects of delirium. Int Psychoger 1991; 3: 319-324. (BV) Reviews 21 papers. The evidence base is very thin.


(ref 1)

  • Avoid the use of sedative or hypnotic medications (eg benzodiazepines) except for the treatment of alcohol or sedative withdrawal.
  • Antipsychotic medication in low doses (see BNF, Section 4.2.1) may sometimes be needed to control agitation, psychotic symptoms or aggression. Beware of drug side-effects (drugs with anticholinergic action and anti-Parkinsonian medication can exacerbate or cause delirium) and drug interactions.


1 Rummans TA, Evans JM, Krahn LE, Fleming KC. Delirium in elderly patients: evaluation and management. Mayo Clinic Proc 1995; 70: 989-998. (BV) Reviews 55 papers. The evidence base is thin.


Referral to the secondary mental-health services is rarely indicated. Referral to a physician is nearly always indicated if:

  • the cause is unclear
  • the cause is clear and treatable but treatment cannot safely be provided within the establishment or
  • drug or alcohol withdrawal, overdose or another underlying condition necessitating in-patient medical care is suspected.