Did you know...
1 in 3 cases of hospital acquired delirium can be prevented.


"It was really scary, but the team was so helpful in explaining what was happening, it took the fear away. I felt so empowered–knowing that I could do something to help my mother."

Patient Family Member

Delirium is a syndrome characterized by confused thinking and disorientation that develops quickly and fluctuates. It is a common reason people are brought to the hospital, and it can also develop after hospital admission. 


Overall, about 1 out of 4 people have delirium at some point during their hospital stay.


Usually delirium is caused by illnesses such as:

  • infections
  • electrolyte imbalances
  • kidney damage
  • liver damage 

In people who are vulnerable to getting delirium, it can also be caused by things like:

  • surgery
  • some medications
  • sleep deprivation
  • dehydration
  • constipation

Things that make people** vulnerable to getting delirium include:

  • old age
  • poor vision
  • difficulty hearing
  • being confined to bed or a wheelchair
  • mild cognitive impairment or dementia

**specific to children: younger than 2 years of age, developmental differences, brain problems such as brain injury, brain infection or seizures.

We don’t know exactly why delirium occurs when people get sick, but the current theory is that the body releases certain inflammatory proteins during illness, which interfere with the way nerve cells in the brain communicate with each other, resulting in the confusion we see with delirium.

Types of delirium

There are three general types of delirium: 

Hypoactive: Patients are noticeably drowsy or slow to respond to words and touch. They may sleep excessively during the day, be withdrawn, apathetic and difficult to motivate. 

Hyperactive: Patients are noticeably agitated and restless. They might be pulling at IV lines or tubes, or trying to get out of bed and putting themselves at risk of falling. They may also communicate differently than normal or not make sense, seem paranoid or experience hallucinations.

Mixed: Patients fluctuate between hyperactive and hypoactive states over the course of a day. At times they might be combative, agitated, and hard to re-direct; at other times they are hard to arouse and have slowed movements.

Recovery and treatment

There are two aspects to treating delirium: 

First, any underlying cause needs to be diagnosed and treated. Delirium is often a sign that there is something else wrong – like an infection or a reaction to a medication. If you feel your loved one may be experiencing delirium, tell the doctor so that he or she can find the underlying cause and treat it.

Second, patients with delirium do best when their environment is as close to home-like as possible.  Unnecessary lines, tubes, and medications are removed; walking and staying out of bed as much as is safely tolerated is encouraged; family members are encouraged to visit during the day; as much light is let into the room as possible during the day; and night-time interruptions are minimized to ensure a good night’s sleep. Often, getting the patient back to their home environment is helpful, if any underlying medical conditions can be treated there safely.

Fortunately, most cases of delirium resolve completely with the appropriate treatment. The time it takes to recover can be unpredictable, though, with some cases only lasting a few days and others taking weeks or longer to return to normal.

It is also important for caregivers to be aware that sometimes patients who experience delirium do not fully return to normal. Although the severe confusion that is seen when the delirium is at its worst nearly always goes away, occasionally patients are left with mild memory or concentration difficulties. This outcome is most frequently seen in patients who develop delirium on top of pre-existing dementia or mild cognitive impairment.

Delirium and Dementia

People with dementia are especially vulnerable to developing delirium in the hospital, and they have a harder time recovering fully from episodes of delirium. Hospitalization should therefore be avoided unless absolutely necessary in patients with dementia.

When patients with dementia develop delirium, it can sometimes be hard to recognize because they already have problems with memory, thinking, or speaking, and they may have hallucinations.  However, dementia is a very gradual, progressive process. If there is a sudden change in cognition in a patient with dementia, it is probably a sign of delirium and means the patient should be evaluated. Sometimes, families will be concerned that their loved one’s dementia is suddenly getting worse very quickly, but this turns out to be an episode of delirium caused by a simple illness like a bladder infection or an extra dose of sleeping medication.


(see How families can help page for ways families can support their loved ones)