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New confusion or not acting like themselves

Also called: Disoriented, foggy thinking, not acting like themselves, altered mental status

New confusion means someone can't think as clearly or quickly as usual. They may not know where they are, the date, or the time. Confusion that comes on suddenly is an emergency, especially in older adults or people with diabetes.

What it isTrouble thinking, focusing, remembering, or deciding
More common inOlder adults, and during hospital stays
Sudden confusionCall 911
Often caused byInfection, low blood sugar, medicines, dehydration
If you think it's an emergency, call 911.Thinking about suicide? Call or text 988.

Overview

A confused person may feel lost, have trouble paying attention, and forget things. Some people act strangely or become upset or aggressive. A simple check is to ask the person their name, age, and the date.

Confusion can come on suddenly or slowly. It's often temporary and gets better when the cause is treated. Sometimes it's linked to dementia and doesn't go away.

When to get medical care

Call 911Confusion that comes on suddenly. Confusion for the first time with no known reason. Confusion with cold or clammy skin, dizziness, a fast pulse, fever, headache, very fast or slow breathing, or shaking you can't control. Sudden confusion in someone with diabetes. Confusion after a head injury. The person may hurt themselves or others, or passes out.
Get care todayLow blood sugar confusion that lasts more than 10 minutes after a sweet drink or snack.
See a doctor soonConfusion that has come on slowly or keeps coming back and hasn't been checked by a doctor.

Causes

Common causes include infections (like a urinary tract infection or pneumonia, especially in older adults), low blood sugar, dehydration, low oxygen, medicines, alcohol or drugs, a head injury, stroke, seizures, and dementia.

OwieClear has pages on 7 conditions that can cause new confusion or not acting like themselves. Each shows how soon to get care.

Common causes

  • Alcohol poisoningMay need emergency care

    Drinking a large amount of alcohol quickly can slow breathing, heart rate, and the gag reflex.

  • Sudden confusion in an older adult (delirium)Often needs care today

    A sudden change in thinking, like confusion, seeing things, being unusually sleepy or agitated, or not acting like themselves.

  • Encephalitis (inflamed brain)May need emergency care

    Inflammation of the brain, usually from a virus such as herpes or West Nile.

Less likely causes

What you can do at home

  • Don't leave a confused person alone. Stay nearby to keep them calm and safe.
  • If low blood sugar might be the cause, give a sweet drink or snack.
  • Introduce yourself each time, even if they know you well.
  • Help them stay oriented. Keep a clock and calendar nearby, remind them where they are, and talk about the day's plans.
  • Keep things calm and quiet.

At the doctor

Treatment depends on the cause. For example, treating an infection often clears up the confusion.

Questions you may be asked

  • Whether the person knows the date, time, and where they are
  • When the confusion started, and whether it came on suddenly
  • Whether it comes and goes
  • Recent and ongoing illnesses
  • Medicines, alcohol, and drugs

The exam

A physical exam, with a careful check of the brain and nerves.

Tests

  • Blood and urine tests
  • A CT scan or MRI of the head
  • Memory and thinking tests

Check your symptoms

Most symptoms have more than one possible cause. The symptom checker looks at all of your symptoms together, plus your age, and shows how soon to get care.

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Sources

Last updated 2026-11-13.