Delirium (Acute Confusion)
Understanding sudden confusion in hospital — causes, management and recovery
Delirium — sometimes called acute confusional state — is a sudden change in mental state characterised by confusion, disorientation and difficulty concentrating. It is extremely common in hospitalised older adults, affecting up to one in three patients on some wards. Despite being common, delirium is frequently unrecognised, particularly in its quieter form where the person is withdrawn rather than agitated.
What is delirium?
Delirium is not a single disease but a medical syndrome — a recognisable pattern of symptoms caused by something going wrong in the body. It comes on acutely (within hours or days) and tends to fluctuate — the person may seem more lucid at some times than others. It is different from dementia (which comes on gradually) but can look similar, and delirium can occur on top of existing dementia.
What causes delirium?
Delirium is nearly always caused by an underlying medical problem. Common triggers include infections (particularly urinary tract infections and chest infections), dehydration, pain that has not been adequately treated, constipation, urinary retention, or a new medication (or the withdrawal of a medication). Severe illness of any kind can also trigger delirium. In most cases, treating the underlying cause allows the delirium to resolve.
Recognising the signs
The most noticeable form of delirium is hyperactive delirium — the person is agitated, restless, may try to pull out drips or get out of bed, and may be seeing or hearing things that are not there. However, hypoactive delirium — where the person is unusually quiet, withdrawn and drowsy — is actually more common and is often missed. Both forms are serious and require prompt attention.
How is delirium managed?
The most important treatment is identifying and treating the underlying cause. Non-pharmacological approaches come first: orienting the person to where they are and what day it is, ensuring they have their glasses and hearing aids, keeping the environment calm and well-lit, encouraging family presence, maintaining a normal day-night routine, and ensuring they are adequately hydrated. Sedating medications are only used as a last resort when a person is at risk of harming themselves or others.
Recovery and longer-term effects
Most people recover from delirium once the underlying cause is treated, though recovery can take days to weeks and is sometimes incomplete. Delirium in hospital is associated with longer stays, increased risk of falls, and a higher chance of being discharged to a care home. Importantly, an episode of delirium can sometimes be the first sign of underlying dementia. If cognitive problems persist after recovery, a memory assessment referral is important. All information here has been prepared following careful evaluation of national clinical guidelines on delirium.