Conditions That Cause Sudden Confusion

Medically Reviewed by Christopher Melinosky, MD on February 05, 2022
3 min read

Sudden confusion, sometimes called delirium or encephalopathy, can be a sign of many health problems. It comes on quickly, within hours or days. It’s different from dementia (like Alzheimer’s disease), which causes slow changes over months or years.

If you or someone you know has sudden mental confusion, you need to see a doctor right away. It’s not normal, whether a person is young or old. Once you can figure out and treat the underlying cause, the confusion usually goes away.

Symptoms can vary. Some people become quiet and withdrawn, while others get nervous and upset. They may:

  • Struggle to focus
  • Seem groggy, like they can’t wake up all the way
  • Mumble or say things that don’t make sense
  • Not recognize you or know where they are
  • Get worked up and upset for no reason
  • "See things that aren’t real

These symptoms will start suddenly. They may come and go or steadily get worse later in the day.

Many conditions or health problems can cause sudden confusion, and some are more serious than others: They include:

Other things can also make you more likely to have sudden confusion, such as if you:

  • Stay in the hospital, especially after an operation
  • Have a lot of medical problems
  • Take a lot of medications, or stop taking a daily medication
  • Are over age 65
  • Have dementia
  • Don’t eat or drink enough
  • Are very overtired
  • Have problems with sight, hearing, or how well you get around

If you’re with someone who suddenly becomes confused, call their doctor or 911. It’s important to get help quickly so they can get treatment ASAP.

While you wait, stay with the person. They may be scared and upset, and they could even get violent or wander off. Try to stay calm and reassure them until they get help.

Doctors will need to figure out the health problem that’s causing the symptoms. They’ll do an exam and may run blood tests, X-rays, CT scans, and MRIs. They’ll also ask questions about the person’s:

  • Specific symptoms
  • Daily medications
  • Alcohol and drug use

Once doctors can get the cause under control, the confusion usually goes away. It can take hours or days to recover, sometimes longer. In the meantime, some people may need medication to keep them calm and help with their confusion.

As the person gets better, it may help to:

  • Make sure they get enough to eat and drink.
  • Encourage them to move around (with your help).
  • Get them on a normal sleep schedule.
  • Surround them with comforting and familiar objects (like family photos).
  • Don’t overwhelm them with too much noise or too many visitors, but don’t isolate them either.

It depends on the cause. Your doctor can tell you what you need to do. But if you or someone you know has had sudden confusion in the past, it’s a good idea to:

  • Make sure your family knows what to do if it happens again.
  • Go over all the medications you or your loved one take with a doctor during each medical appointment. Check that it’s safe to take them together.
  • Before any kind of surgery, talk to the health care team so they can take steps to lower any chances of sudden confusion.