Delirium occurs when the normal sending and receiving of signals in the brain become impaired. This impairment is most likely caused by a combination of factors that make the brain vulnerable and trigger a malfunction in brain activity.
Delirium may have a single cause or more than one cause, such as a combination of a medical condition and drug toxicity. Sometimes no cause can be identified. Possible causes include:
- Certain medications or drug toxicity
- Alcohol or drug intoxication or withdrawal
- A medical condition, such as a stroke, heart attack, worsening lung or liver disease, or an injury from a fall
- Metabolic imbalances, such as low sodium or low calcium
- Severe, chronic or terminal illness
- Fever and acute infection, particularly in children
- Urinary tract infection, pneumonia or the flu, especially in older adults
- Exposure to a toxin, such as carbon monoxide, cyanide or other poisons
- Malnutrition or dehydration
- Sleep deprivation or severe emotional distress
- Pain
- Surgery or other medical procedures that include anesthesia
Several medications or combinations of drugs can trigger delirium, including some types of:
- Pain drugs
- Sleep medications
- Medications for mood disorders, such as anxiety and depression
- Allergy medications (antihistamines)
- Asthma medications
- Steroid medicines called corticosteroids
- Parkinson’s disease drugs
- Drugs for treating spasms or convulsions