Diseases & Conditions A - Z
powered by Talix

Decreased Consciousness

What Is Decreased Consciousness?

The major characteristics of consciousness are alertness and being oriented to place and time. Alertness means that you are able to respond appropriately to the people and things around you. Being oriented to place and time means that you know who you are, where you are, where you live, and what time it is.

When consciousness is decreased, your ability to remain awake, aware, and oriented is impaired. Impaired consciousness is a medical emergency.

Consciousness and the Brain

The brain is the main organ responsible for maintaining consciousness. Your brain requires certain amounts of oxygen and glucose in order to function properly.

Many substances you consume can affect your brain chemistry. These substances can help to maintain or decrease consciousness. For example, caffeine is a stimulant, which means that it raises your levels of brain activity. Caffeine can be found in many foods you eat every day, such as coffee, soda, and chocolate. On the other hand, painkillers and tranquilizers make you drowsy. This side effect for these substances is a form of impaired consciousness.

Diseases that damage your brain cells can also cause impaired consciousness. A coma is the most severe level of consciousness impairment.

Symptoms of Decreased Consciousness

Symptoms that may be associated with decreased consciousness include:

  • seizures
  • loss of bowel or bladder function
  • poor balance
  • falling
  • difficulty walking
  • fainting
  • light-headedness
  • irregular heart beat
  • rapid pulse
  • low blood pressure
  • sweating
  • fever
  • weakness in the face, arms, or legs

Types of Decreased Consciousness

Levels of impaired consciousness include confusion, disorientation, delirium, lethargy, stupor, and coma.


Confusion is marked by the absence of clear thinking and may result in poor decision-making.


Disorientation is the inability to understand how you relate to people, places, objects, and time. The first stage of disorientation is when you are disoriented with respect to time (years, months, days). This is followed by disorientation with respect to place, which means you may not know where you are.

Loss of short-term memory follows disorientation with respect to place. The most extreme form of disorientation is when you lose the memory of who you are.


If you are delirious, your thoughts are confused and illogical. People who are delirious are often disoriented. Their emotional responses range from fear to anger. People who are delirious are often highly agitated.


Lethargy is a state of decreased consciousness that resembles drowsiness. If you are lethargic, you may not respond to stimulants like the sound of an alarm clock or the presence of fire.


Stupor is a deeper level of impaired consciousness in which it is very difficult for you to respond to any stimuli, except for pain.


Coma is the deepest level of impaired consciousness. If you are in a coma, you can’t respond to any stimulus, not even pain.

Common Underlying Causes of Decreased Consciousness

Drugs, alcohol, substance abuse, certain medications, epilepsy, low blood sugar, stroke, and lack of oxygen to the brain are common causes of decreased consciousness.

Other underlying causes of decreased consciousness include:

  • cerebral hemorrhage
  • dementia (Alzheimer’s)
  • head trauma
  • heart disease
  • heat stroke
  • liver disease
  • uremia (end stage kidney failure)
  • shock

What to Expect When You See the Doctor

Diagnosis and treatment of decreased consciousness begins with a complete medical history and physical examination, which includes a detailed neurological evaluation. Your doctor will want to know about any medical problems you have (such as diabetes, epilepsy, or depression), and any medications you are taking (such as insulin or anticonvulsants). They will also ask if you have a history of abusing illegal or prescription drugs or alcohol.

In addition to your complete history and physical, the doctor may order the following tests:

  • CBC (complete blood count): finds if you have a low hemoglobin level, which indicates anemia. An elevated white blood cell count indicates infections, such as meningitis or pneumonia.
  • toxicology screen: detects the presence and levels of medications, illegal drugs, and poisons in your system
  • electrolyte panel: measures levels of sodium, potassium, chloride, and bicarbonate
  • liver function tests: measure the health of your liver
  • electroencephalogram (EEG): uses scalp electrodes to evaluate brain activity
  • electrocardiogram (EKG): evaluates heart rate, rhythm, and health
  • chest X-ray: evaluates the heart and lungs
  • CAT scan of the head: uses X-rays to make high-resolution images of the brain that can help find any abnormalities
  • MRI of the head: uses nuclear magnetic resonance to make high-resolution images of the brain

Treating Decreased Consciousness

Treatment for decreased consciousness depends on what’s causing it. You may need to change medications, begin new treatment, or simply treat the symptoms to address the underlying cause. For example, you need emergency medical treatment and possibly surgery to treat a cerebral hemorrhage. On the other hand, there is no cure for Alzheimer’s, so your healthcare team will work with you to come up with strategies to treat any symptoms and maintain quality of life as long as possible.

Talk to your doctor as soon as you think you may be experiencing decreased consciousness so they can start your treatment as soon as possible.

Outlook for Decreased Consciousness

Decreased consciousness can be a sign of a serious condition. Getting prompt medical attention is important for your long-term outlook. Your outlook can become worse the longer you spend in less than full consciousness.

Content licensed from:

Written by: Verneda Lights
Medically reviewed on: Jan 25, 2015: Deborah Weatherspoon, Ph.D, MSN, RN, CRNA

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
Symptom Search
Enter your symptoms in our Symptom Checker to find out possible causes of your symptoms. Go.
Drug Interaction Checker
Enter any list of prescription drugs and see how they interact with each other and with other substances. Go.
Pill Identifier
Enter its color and shape information, and this tool helps you identify it. Go.
Drugs A-Z
Find information on drug interactions, side effects, and more. Go.