Alertness - decreased


Decreased alertness is a state of reduced awareness.A coma is a state of decreased alertness from which a patient cannot be awakened. A long-term coma is called a vegetative state.See also:DeliriumDementia

Alternative Names

Stuporous; Mental status - decreased; Loss of alertness; Decreased consciousness; Changes in consciousness; Obtundation; Coma; Unresponsiveness

Common Causes

Many conditions can cause decreased alertness, including:Chronic kidney diseaseExtreme tiredness or lack of sleepHigh blood sugar or low blood sugarInfection that is severe or involves the brainLiver failureThyroid conditions that cause low thyroid hormone levels or very high thyroid hormone levelsBrain disorders or injury, such as:Dementia or Alzheimer's diseaseHead traumaSeizureStrokeInjury or accidents, such as:Diving accidents and near drowningHeat strokeVery low body temperature (hypothermia)Heart or breathing problems, such as:Abnormal heart rhythm (arrhythmia)Lack of oxygen (hypoxia) from any causeLow blood pressure (hypotension)Low sodium levels in the bloodSevere heart failureSevere lung diseasesVery high blood pressureToxins and drugs, such as:Alcohol abuse (binge drinking or damage from long-term alcohol use)Exposure to heavy metals, hydrocarbons, or toxic gasesOveruse of drugs such as opiates, narcotics, sedatives, and anti-anxiety or seizure medicationsSide effect of almost any medicine, such as those used to treat seizures, depression, psychosis, and other illnesses

Home Care

Get medical help for any decrease in consciousness, even when it is due to alcohol intoxication, fainting, or a seizure disorder that has already been diagnosed.See the article on seizures for tips on how to care for a person who is having a seizure.Persons with epilepsy or other seizure disorder should carry a Medic-Alert bracelet or pendant describing their condition. They should avoid situations that have triggered a seizure in the past.

Call your health care provider if

Get medical help if someone has decreased alertness that cannot be explained. Call your local emergency number (such as 911) if normal alertness does not return quickly.

What to expect at your health care provider's office

Most often, a person with decreased consciousness will be evaluated in an emergency room.The doctor will perform a physical examination. The exam will include a detailed look at the heart, breathing, and nervous system.The health care team will ask questions about the person's medical history and symptoms, includingTime pattern When did the decreased alertness happen?How long did it last?Has it ever happened before? If so, how many times?Did the person behave the same way during past episodes?Medical history Does the person have epilepsy or a seizure disorder?Does the person have diabetes?Has the person been sleeping well?Has there been a recent head injury?Other What medications does the person take?Does the person use alcohol or drugs on a regular basis?What other symptoms are present?Tests that may be done include:Chest x-rayComplete blood count or blood differentialCT scan or MRI of the headElectrocardiogram (ECG)Electroencephalogram (EEG)Electrolyte panelToxicology panelUrinalysisTreatment depends on the cause of the decreased alertness. How well a person does depends on the cause of the condition. The longer the person has had decreased alertness, the worse the outcome.


Blok BK, Newman TM. Syncope. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 52.Huff JS. Altered mental status and coma. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 259.Kirsch TD. Head injury. In: Tintinalli JE, Kelen GD, Stapczynski JS, Ma OJ, Cline DM, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed. New York, NY: McGraw-Hill; 2004:chap 255.Huff JS, Martin ML. Altered mental status and coma. In: Wolfson AB, Hendey GW, Ling LJ, et al, eds. Harwood-Nuss' Clinical Practice of Emergency Medicine. 5th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 14.

Review Date: 4/3/2011
Reviewed By: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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