Delirium: practical overview
How to recognize delirium, why it is urgent, and what clinicians assess first.
Delirium: practical overview
How to recognize delirium, why it is urgent, and what clinicians assess first.
Key points
- Delirium is an acute, fluctuating disturbance of attention and thinking—treat it as a medical alarm, not “normal confusion”.
- Most cases have multiple triggers (infection, medications, dehydration, pain, hypoxia, urinary retention/constipation). The job is to find and fix them quickly.
- Quiet (hypoactive) delirium is common and dangerous because it is easily missed.
Clinical scenario
An older adult becomes “not themselves” over hours to days: alternating between agitation and drowsiness, unable to sustain attention, with sleep–wake reversal. Family reports a recent medication change and poor fluid intake.
What this usually means
Delirium reflects temporary brain dysfunction under systemic stress. The key feature is impaired attention with rapid onset and fluctuations. Unlike dementia, delirium develops quickly and often improves when the underlying illness is treated.
What to check systematically
Think in three buckets: (1) too little brain fuel (hypoxia, hypoglycemia, hypotension, severe anemia), (2) toxic load (new or high-dose sedatives, anticholinergics, opioids; alcohol/withdrawal; renal/hepatic failure), and (3) inflammation and stress (infection, postoperative state, pain, urinary retention, constipation, sleep deprivation). Document baseline cognition and function, and bring a complete medication list including OTC sleep aids.
Management priorities
Start with safety and physiology: airway/breathing/circulation, oxygen if needed, glucose check, treat fever and pain, correct dehydration and electrolytes, relieve urinary retention and constipation. Optimize the environment: daylight exposure, clocks/calendars, glasses/hearing aids, calm reorientation, mobility with assistance, and protect sleep at night. Medication to sedate is not first-line; it is reserved for immediate risk and tailored to the cause.
Prevention & recovery
Recovery often takes days to weeks. Maintain hydration, mobility, regular sleep, and review medications after discharge. If delirium occurred once, future episodes are more likely during illness, surgery, or medication changes—plan preventive measures early.
Practical tables
| Red flag | Why it matters | What to do |
|---|---|---|
| New focal weakness, facial droop, speech difficulty | Possible stroke | Call emergency services immediately |
| Breathing difficulty, low oxygen saturation, cyanosis | Hypoxia can rapidly worsen delirium | Urgent medical assessment |
| Seizure or loss of consciousness | Potential life-threatening cause | Emergency care |
| Severe drowsiness/hard to arouse | May signal sepsis, drug effect, metabolic crisis | Emergency care |
| Very rapid onset after a new drug or dose change | Medication toxicity or interaction | Seek same-day review; bring medication list |
| Quick bedside checks | What you’re looking for | Common next step |
|---|---|---|
| Attention (months backwards, digit span) | Inability to sustain focus | Treat as delirium until proven otherwise |
| Vitals + oxygen saturation | Hypoxia, infection, shock | Stabilize and search cause |
| Glucose (if available) | Hypoglycemia/hyperglycemia | Correct urgently |
| Urine output/retention, constipation | Very common reversible triggers | Bladder scan, bowel regimen |
| Medication review | Anticholinergics, sedatives, opioids, polypharmacy | Deprescribe/adjust where appropriate |
Related topics
Causes of delirium • Diagnosis and treatment • Prevention • When to seek urgent care