Causes of delirium
Infections, medications, metabolic problems and common hidden triggers — a systematic approach.
Causes of delirium
Infections, medications, metabolic problems and common hidden triggers — a systematic approach.
Key points
- Delirium is usually multifactorial; assume more than one contributor until proven otherwise.
- Common triggers: infection, dehydration, medication effects, pain, hypoxia, metabolic derangements.
- In older adults, even mild illness can precipitate delirium when baseline reserve is low.
Clinical scenario
A patient develops abrupt changes in attention, behavior, or sleep–wake rhythm. Symptoms fluctuate, and caregivers report either agitation or unusual quietness and withdrawal.
What this usually means
Delirium has a threshold model: baseline vulnerability (age, dementia, sensory impairment, frailty) plus an acute stressor (infection, drugs, dehydration, surgery) pushes the brain beyond compensation.
What to check systematically
Collect: exact onset and fluctuation pattern; baseline cognition and independence; new symptoms (fever, cough, dysuria, pain, dyspnea); fluid intake and urine output; bowel pattern; alcohol use; and a complete medication list including supplements and OTC products. In medical settings, typical initial tests include vitals, oxygenation, glucose, basic labs (electrolytes, kidney/liver function), urinalysis when indicated, and focused imaging based on exam.
Management priorities
First address immediate threats (oxygenation, glucose, hemodynamics) and treat pain and infection promptly. Remove triggers: stop or reduce deliriogenic medications where possible, correct dehydration/electrolytes, treat constipation/urinary retention, and restore sleep cues. Use calm, repeated reorientation and involve family; avoid restraint unless absolutely necessary. If medication is required for severe agitation or hallucinations causing danger, use the lowest effective dose and review daily.
Prevention & recovery
Maintain routines, hydration, mobility, and sensory aids. After an episode, schedule a medication review and plan delirium prevention for future hospitalizations or surgeries. Monitor for persistent cognitive symptoms and seek reassessment if confusion does not steadily improve.
Practical tables
| Common contributor | Clues | Practical action |
|---|---|---|
| Medication effect/interaction | New drug or dose change; OTC sleep/cold remedies | Review all medicines; ask clinician about deprescribing |
| Infection | New weakness, urinary changes, cough; may lack fever in frail adults | Same-day medical evaluation |
| Dehydration | Low intake, dry mouth, reduced urine | Encourage fluids if safe; assess for IV fluids if needed |
| Hypoxia | Shortness of breath, low SpO₂ | Urgent assessment; oxygen as directed |
| Pain/retention/constipation | Restlessness, guarding, minimal stool/urine | Treat pain; address bladder/bowel triggers |
| Communication tip | Why it helps |
|---|---|
| One idea per sentence, slow pace | Attention is impaired—reduce cognitive load |
| Use clocks, calendars, daylight | Restores orientation and circadian rhythm |
| Confirm hearing aids and glasses | Reduces misinterpretation and hallucinations |
| Mobilize safely every day | Improves sleep, reduces pneumonia/constipation |
| Keep nights quiet and dark | Sleep protection lowers delirium severity |
Related topics
Diagnosis and treatment • Prevention • When to seek urgent care