Delirium (acute confusion): signs, causes and how to help

The Royal College of Psychiatrists describes delirium as a state of mental confusion that starts suddenly and is caused by a physical condition of some sort. The person may not know where they are, what time it is or what is happening to them. NICE Clinical Knowledge Summaries defines it as a common clinical syndrome of disturbed cognition, attention, consciousness or perception developing over hours to days with a fluctuating course, and which cannot be better explained by a pre-existing or developing dementia.

Because it is caused by a physical condition, finding and treating that cause is the heart of care.

The NHS lists signs of confusion: not being able to think or speak clearly or quickly, not knowing where you are, struggling to pay attention or remember things, and seeing or hearing things that are not there. It suggests asking the person their name, age and today's date, and says that someone who seems unsure or cannot answer probably needs medical help.

The Royal College of Psychiatrists adds that a person with delirium may be agitated or restless, unable to sit still and wandering, or very slow and sleepy; may sleep in the day and wake at night; may have quickly changing moods, vivid frightening dreams, or worries that others want to harm them; and may hear or see things that are not there. It is usually worse at night.

NICE CKS classifies delirium into three subtypes. Hypoactive, the most common, means the person becomes withdrawn, quiet, lethargic and sleepy. Hyperactive involves restlessness, agitation and sometimes aggression. Mixed shows features of both. The quiet form is often missed, as the Royal College example of a patient thought to be depressed illustrates, so a change from someone's normal behaviour is worth reporting even if they seem calm.

The NHS lists common causes of sudden confusion including infection, with urinary tract infections common in older people and people with dementia, stroke or TIA, low blood sugar in people with diabetes, head injury, some prescription medicines, alcohol poisoning or withdrawal, drugs, carbon monoxide poisoning, a severe asthma attack or other lung or heart problems, and certain epileptic seizures. It warns against trying to self-diagnose.

The Royal College of Psychiatrists adds a chest infection, high temperature, pain killers and steroids, dehydration, low salt levels, anaemia, liver or kidney problems, suddenly stopping drugs or alcohol, major surgery, constipation and being in an unfamiliar place. It says there is often more than one cause and sometimes none is found.

NICE CKS lists risk factors as age over 65, existing cognitive impairment including dementia, frailty, multiple health conditions, trauma, sensory impairment and malnutrition, with precipitating factors including infection, metabolic disturbance, urinary retention, constipation, pain, environmental change, drugs and alcohol. The Royal College says people are also more likely to have delirium if they have had it before, have poor hearing or eyesight, or have recently had surgery.

The two can look alike but behave differently. Delirium starts over hours or days, fluctuates and is tied to an acute physical trigger, while dementia develops gradually. The NHS notes that gradual forgetfulness or confusion in an older person can be a sign of dementia and recommends seeing a GP if you are worried about it.

The conditions often coexist. NICE CKS lists dementia as a risk factor for delirium and lists development or worsening of dementia as a possible complication. Because delirium can be superimposed on dementia, relatives who know the person's usual state are invaluable to clinicians; the Royal College stresses that a person may be too confused to describe what is happening, so the doctor needs to talk to someone who knows them well.

NICE CKS describes the primary care assessment: asking about the onset and course of symptoms, usual functioning and thinking, risk and precipitating factors, medicines, alcohol and drug use and sensory impairment, getting a history from relatives or carers, checking vital signs, and considering a cognitive screening test and targeted investigations. Initial management includes arranging urgent hospital admission for assessment and treatment depending on the symptoms, likely cause, distress, risk of harm and the support available. If the person lacks capacity to decide about admission, the Mental Capacity Act may be considered.

Treatment aims at the cause. The Royal College gives the example that a chest infection is treated with antibiotics. Alongside this come simple measures to help the person feel safer: explaining what has happened, reassurance, a large clock and a note saying where they are, familiar objects from home, visits from friends and family, and making sure glasses and hearing aids are present and working. NICE CKS describes safe low-stimulation environments, reorientation, continuity of care, safe mobility and better sleep patterns, with specialist advice if the person is severely distressed.

Sedatives are used cautiously. The Royal College says they may calm someone but can make delirium worse, and should only be prescribed if the person is a danger to themselves or others, very agitated or anxious, believes others are trying to harm them, is seeing or hearing things, needs calming for important investigations, or is withdrawing from alcohol. Low doses of antipsychotics can help with hallucinations, and any sedative should be at the lowest dose for the shortest time. These are clinical decisions made by the treating team, not something families should seek to arrange.

The NHS advice while waiting for an ambulance is to stay with the person, tell them who you are and where they are, keep reassuring them, use simple words and short sentences, note down any medicines they take, and not ask lots of questions or stop them moving about unless they are in danger.

The Royal College suggests staying calm, speaking in short sentences and repeating if needed, reminding them of the time and date with a visible clock or calendar, helping them to eat and drink, making sure someone they know is with them especially in the evening when confusion often worsens, and keeping a light on at night. Bringing a list of medicines, a recent history and the person's usual abilities helps the team.

The Royal College says delirium usually gets better when the cause is treated. Recovery may be quick, but sometimes takes several days or weeks. Afterwards people may recall it like a dream, remember frightening emotions, or recall little, especially with existing memory problems. Sitting down with someone who can explain what happened, perhaps using a diary of each day, helps most people.

It also says an episode makes another more likely if the person becomes unwell again, so teams and families should know about previous delirium and report new confusion urgently. NICE CKS lists possible complications including longer hospital stay, risk of long-term care, development or worsening of dementia, functional decline and distress, and notes the outlook varies with baseline health, cause and subtype.

Sudden confusion is an emergency route issue: A&E, 999 or an urgent GP assessment through the NHS. Whichever hospital someone is in, new confusion should trigger a medical assessment for its cause.

Private care can be useful afterwards, for example a memory assessment or geriatric review once the acute illness has settled, to see whether underlying cognitive problems were unmasked. Share the hospital discharge summary with your GP so the episode is recorded.