Warning

Audience

  • North NHS Highland only
  • Secondary care only
  • Adults only

Delirium is primarily a reflection of the brain being under stress from an acute change in the health of an individual. It can be defined as 'an acute deterioration in mental functioning arising over hours or days that is triggered mainly by acute medical illness, surgery, trauma or drugs’. Fluctuating symptoms with altered alertness and concentration are hallmarks of the condition.

Delirium is a frequently occurring medical issue, prevalent in all surgical, medical and level 2 and 3 areas. It is under-detected, complicated and harmful, but at risk groups can be highlighted to prevent or minimize delirium. It is relevant to all staff, including medical, nursing, allied health professionals and pharmacy, and involves identifying significant health problems, some of which are life-threatening. The combination of effective prevention and management will lead to less distress for patients, carers and staff, along with reduced falls, length of hospital stay and mortality. In up to 30% of patients no cause is identified.

The relevance of delirium is recognized nationally through the Scottish Delirium Association (SDA) see SDA delirium pathway and the development of SIGN 157 “Risk reduction and management of delirium

This guide is particularly aimed at older adults, the most likely population to experience delirium, however the principles of care in all age groups are the same. More robust patients may need higher doses of medication than those described below.

Exclusions

Quick reference guide

  • Ensure that new confusion is scored appropriately on the NEWS2 chart when appropriate. This highlights to the whole team that delirium is present, relevant and needs action.
  • Differentiate between confusion and language impairment, i.e. dysphasia.
  • Do NOT prescribe delirium. Prescribe appropriately, especially in those already at higher risk of delirium. NB medicines can directly cause delirium. 
  • Reduce and stop medication prescribed for distress when possible, and, if being used at discharge, ensure clear follow-up advice is in place for its review.
  • Good communication with relatives/carers is important and can reduce distress. Explain clearly to patients their diagnosis of delirium and its consequences, as patients are often frightened about their experiences and have concern that they are developing a mental health disorder
    • SIGN has produced an information booklet for patients or relatives, click here
    • The Royal College of Psychiatrists have developed a shorter leaflet, click here.

Presentation

Delirium can present as:

  • Hypoactive delirium: with drowsiness or showing loss of attention/ concentration
  • Hyperactive delirium: distress/ agitation/ hallucinations/ delusions/ paranoid.
  • A mixed presentation of hypo- and hyper- active delirium

Fluctuating symptoms are frequent and at times an individual may superficially seem close to their normal, this variability and fluctuation should be recognized as supporting the diagnosis of delirium.

Recognizing delirium can be difficult if you are unfamiliar with the patient. It is important to appreciate reports of a change from normal in the person by staff or family/carers who know the person as indications of a potential new, significant illness. Collaborative history taking is essential in highlighting these details.

The change from normal is the important factor to assist in detecting early or subtle delirium; examples of how delirium can be described are: ‘They are a bit vague’, ‘just slept all morning’, ’doesn’t wake up when examined but yesterday was chatty’, ‘not wanting to eat or drink or engage with staff’, ‘thought they were somewhere else’, ‘not concentrating’, ‘seeing things on the curtains and on the wall’.

Picking up on these comments by using the Single Question in Delirium (SQID) and the TIME bundle allows the early detection and management of delirium, and reduces the associated poor outcomes; including increased mortality, length of stay and morbidity.

  • SQID: Is this patient more confused than before?
  • TIME bundle: part of NHS Highland nursing documentation. See: HIS Think Delirium

Groups at risk of delirium

Groups at risk of delirium are those with:

Acute illness, dementia, age over 70 years, frailty, sensory impairment, polypharmacy, recent anaesthetic/surgery, hip fracture surgery, being catheterised, recent discharge from acute hospital, use of opioids, benzodiazepines, oral anti-cholinergics, restraint, depression, history of alcohol misuse, acute or chronic pain.

Delirium is often driven from pathology out with the brain, but at risk groups often have underlying brain pathology, ie, previous stroke, Parkinson’s disease.

All patients at risk of delirium should have a medication review conducted by an experienced healthcare professional. (SIGN 157)

Reducing the risk of delirium is achievable through:

  • Orientation and ensuring patients have their glasses and hearing aids
  • Promoting sleep hygiene
  • Early mobilisation
  • Pain control
  • Prevention, early identification and treatment of postoperative complications
  • Maintaining optimal hydration and nutrition
  • Regulation of bladder and bowel function
  • Provision of supplementary oxygen, if appropriate.
  • Minimizing ward moves in patients susceptible to delirium

Imaging

Brain imaging is not usually part of the first-line assessment, unless there is concern due to anticoagulation, head injury or focal neurological signs or persistent symptoms.

Legal considerations in delirium

Consider whether Adults with Incapacity (AWI) and/or Emergency Detention Certificates (EDC) are appropriate.

An EDC requires all 5 criteria below to be met:

  1. It is likely that the person has a mental disorder;
  2. Because of that mental disorder it is likely that the person has significantly impaired decision making ability (SIDMA) regarding medical treatment of the disorder;
  3. It is necessary as a matter of urgency to detain the person in hospital to decide what medical treatment is needed for the suspected mental disorder;
  4. There would be a significant risk to the person’s health, safety or welfare or the safety of any other person if the person was not detained in hospital;
  5. Arranging to grant a short term detention certificate would involve undesirable delay.

Medication

Unmanageable distress

  • If patients’ symptoms threaten their safety or the safety of others prescribe a low dose of one medication (start low: go slow) and review every 24 hours. Consider capacity to consent to treatment (AWI Section 47)
  • If patient is refusing oral medication repeatedly it may be appropriate to consider administration of medication covertly. The appropriate forms must be completed prior to this (AWI covert medication care plan) and consent sought from welfare attorney/guardian if in place. Method of covert administration must be discussed with pharmacy. See Mental Welfare Commission Covert medicine policy.
  • Local advice reinforces that there is no evidence of any specific antipsychotic having benefit over others.
    The use of all medications (other than haloperidol) is off-label. Please refer to the Royal College of Psychiatrists guideline: Use of licensed medicines for unlicensed applications in psychiatric practice.
  • In severe cases you may need to exceed the maximum doses below, this should trigger consideration of specialist referral.

Oral antipsychotics:

Used in low dose as below

When using medication on an ‘as required basis’, if more than 2 doses are required in a 24 hour period, then regular oral low dose antipsychotic should be considered, with the maximum daily doses as listed (including when required doses)

Medication Starting dose Max daily dose Minimum interval Comments
Risperidone 250 micrograms once or twice daily 1mg 6 hours Caution in Parkinson's disease or Lewy body disease
Olanzapine 2.5mg daily 5mg 12 hours Caution in Parkinson's disease or Lewy body disease
Haloperidol 500 micrograms up to twice daily 2mg 6 hours Licensed indication but;
  • Contraindicated in QTC prolonging medication
  • Pre-treatment ECG required
  • Contraindicated in Parkinson's disease
  • See recent MHRA warning

 

Benzodiazepines

Medication Starting dose Max daily dose Minimum interval Comments
Lorazepam 500 micrograms to 1mg up to twice daily 2mg 4 hours
  • Can be used in Parkinson's disease, Lewy Body Dementia or if signs of Parkinsonism
  • Consider the potential risk of worsening/prolonging delirium with benzodiazepine

 

Intramuscular

Only use if oral route is unachievable. NHS Highland Rapid tranquilisation (Guidelines) must be followed, including patient monitoring requirements,
If more than 2 doses of IM medication are required, antipsychotic at low dose should be prescribed to limit further IM usage.

Medication Starting dose Max daily dose Minimum interval Comments

FIRST LINE Lorazepam

500 micrograms daily 500 micrograms to 1 mg 4 hours Consider potential risk of worsening / prolonging delirium with benzodiazepines
Haloperidol 500 micrograms daily 500 micrograms 6 hours Licensed indication but;
  • Contraindicated with QT prolonging drugs
  • Pre-treatment ECG required
  • Contraindicated in Parkinson's disease
  • See recent MHRA warning.

Younger or more robust patients may need higher doses of medication.

Daily review where there is unmanageable agitation / distress, to consider the potential causes for delirium and "consider specialist referral".

It may be appropriate to prescribe a regular low dose of a medication and an extra ‘as required’ dose on the prescription chart.

If different routes of a medication are prescribed, these may need to be prescribed separately, taking into account the different doses that can be given via different routes.

Discharge advice

Delirium as a diagnosis and any recognized triggers should be highlighted on the discharge letter.  Follow up after discharge should be undertaken if the delirium has not resolved fully during the inpatient stay. If there is ongoing concern regarding the potential for dementia, then cognitive screening should take place once delirium has fully resolved, followed by referral to Older Adult Psychiatry services. See SDA delirium pathway

Referral to older adult psychiatry

Referral criteria

  • There is some doubt about diagnosis and a primary psychiatric condition is a possibility.
  • There is difficult to manage behaviour persisting despite utilising the non-pharmacological and pharmacological guidance in this document, or there are side effects to psychotropic medication.
  • Advice is required for a pre-morbid psychiatric condition.
  • Advice is required regarding detention under the mental health act, or as soon as possible after the patient has been detained on an Emergency Detention Certificate.

Health care professional resources

Abbreviations

AWI: Adults with Incapacity
ECG: Electrocardiogram
EDC: Emergency Detention Certificate
IM: Intramuscular
MG: milligrams
MHRA: Medicines and Healthcare products Regulatory Agency
NICE: National Institute for Health and Care Excellence
PSM: Pharmaceutical Science & Medicines
QT: QT interval
QTC: Corrected QT interval
SDA: Scottish Delirium Association
SIDMA: Significantly Impaired Decision-Making Ability
SIGN: Scottish Intercollegiate Guidelines Network
SQID: Single Question in Delirium
TIME: Think, Investigate, Manage, Engage

Editorial Information

Last reviewed: 30/03/2026

Next review date: 31/03/2029

Version: 2

Approved By: TAM subgroup of the ADTC

Reviewer name(s): Dr D Gray, Associate Specialist Medicine for Elderly .

Document Id: TAM528