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Delirium (Acute Confusion)
Delirium is a sudden change in mental state — confusion, disorientation or drowsiness — usually triggered by illness. It is a medical emergency in older people and is often reversible.
Causes & risk factors
- Infections (chest, urine and others)
- Dehydration or constipation
- Medicines or alcohol/withdrawal
- Pain or a recent operation
- Low oxygen or salt imbalances
- A new or worsening illness
Common symptoms
- Sudden confusion or disorientation
- A change from the person’s usual self, often over hours to days
- Fluctuating alertness through the day
- Drowsiness or, conversely, agitation
- Seeing or hearing things that are not there
- Difficulty concentrating or following conversation
Tests & diagnosis
- Urine test (for infection)
- Complete blood count (CBC)
- Electrolytes
- Kidney function (RFT)
- Blood sugar
- CRP (infection marker)
Treatment & management
- Find and treat the underlying cause (often infection) — this is the priority
- Correct dehydration, constipation and any salt imbalance
- Review and adjust medicines that may be contributing
- A calm, well-lit environment with familiar faces and reassurance
- Ensure glasses and hearing aids are used
- Manage pain and support sleep
When to see a doctor urgently
- A sudden change in confusion, alertness or behaviour in an older person — seek urgent care
- New confusion with fever, breathlessness or being very unwell — emergency
- Drowsiness that is hard to rouse — emergency
- Agitation or hallucinations that are new — urgent
Frequently asked questions
How is delirium different from dementia?
Delirium comes on suddenly (hours to days), often fluctuates, and is usually triggered by a treatable illness. Dementia develops gradually over months to years. Delirium can occur on top of dementia and needs urgent assessment.
Is delirium reversible?
Often, yes. When the underlying cause — such as an infection or dehydration — is treated, delirium usually improves, though full recovery can take time in older people.
Explore more
Sources & further reading
- World Health Organization (WHO)
- MedlinePlus — U.S. National Library of Medicine
- Ministry of Health & Family Welfare, India
- Indian Council of Medical Research (ICMR)
Reviewed by Dr. Sanjay Anbu, MBBS. MedDroid is an AI medical assistant and can make mistakes. It provides general health information, not a diagnosis or medical advice — always consult a qualified clinician. In an emergency, contact your local emergency number immediately.