Causes of fainting, altered mental status, sudden altered mental status, unconsciousness

Mental status is also known as Level of Consciousness (LOC).

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Levels of consciousness:

Person, place, time, event

(their name is the last thing of these they’ll remember).

A person who is fully oriented to their surroundings and situation should be able to tell you their name,
where they are, what time it is (not to the exact hour but at least if it is morning or evening, what month and year it is)
and what just happened to them.

An infant can’t answer questions about these, but you could call out their name and see if they respond.

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I wrote this webpage so that my students can realize there are many, many reasons a person might faint or otherwise lose consciousness.

You can become familiar with all of these just by reading through the page twice.
Read it once, wait a week, and read it again.

(Students do not have to memorize all these, but depending on which program they are in, they might want to eventually.)


Reasons why a person might become unconscious or semi-conscious

Also known as:


Alcohol or other substance abuse or misuse


Insulin (diabetes, high or low blood sugar)



Trauma, especially head injury




Altered mental status (and possibly a confused or combative state) can be caused by:

any of AEIOUTIPS above



electrolyte imbalance (hyponatremia)

severe dehydration

shock and/or any condition that results in less blood flow (and therefor less oxygen) to the brain

conditions resulting from mental, emotional or behavioral disorders

severe drug withdrawal – (Delirium tremens or other) is sometimes mistaken for an acute psychiatric problem

Remember that someone with altered mental status might not be able to give you accurate answers to your questions.


SUDDEN Altered mental status, (and possibly a confused or combative state) AKA delirium, which can indicate a life-threatening condition,

can be caused by any of the above.

Note that this can be relatively common in elderly people and might seem like dementia, but is not.

infections including urinary tract infections, a wound, pneumonia

cancer spreading to the brain and causing hallucinations

a stroke

head injury with intracranial bleeding

severe burns

use of or withdrawal from alcohol/drugs

poisoning from lead, mercury, carbon monoxide, pesticides

chronic lung disease


Note that heatstroke or diabetes can seem like an acutely intoxicated person.


causes of fainting

fright, stress or excitement

tight clothing at neck

carbon monoxide poisoning

dehydration, especially severe dehydration brought on by diarrhea, vomiting or sweating, especially if the victim has not been drinking enough fluids

slow gastrointestinal bleeding with or without pain

blood volume changes (stood up too fast after prolonged sitting or lying down (more likely for pregnant, elderly), after a large meal (especially with alcohol))


inflammation of inner or middle ear


panic disorders and hyperventilation

dysrhythmia causing a fast heartbeat

a very slow heart rate

standing too long, especially in the heat

benign hyperventilation: an anxious person (fear of heights, animals, etc.) hyperventilates (breathes rapidly and deeply) which causes dizziness, a sensation of choking, tingling in hands & feet, chest pain &/or tightness, blurred vision and more. These symptoms being close to those of a heart attack or other serious problem can cause more concern and more hyperventilation sometimes leading to fainting.
(No, do not have them breathe into a paper bag.)

some medications for high blood pressure or heart disease

recent arrival at high altitude



STOPEATS is an acronym to help people learn or memorize some of the reasons why a victim could have a decreased level of consciousness or some causes of a seizure

Sugar – diabetic – (or low blood sugar – hypoglycemia or hyperglycemia) (When did they last eat or drink?)

Temperature – extreme high or cold temperature (hypothermia, hyperthermia)

Oxygen – abnormal levels of oxygen, (see also the A for altitude below)

Pressure – increasing intracranial pressure (ICP) (brain swelling) due to head trauma / concussion / traumatic brain injury (TBI), bleeding in the brain, high-altitude cerebral edema (HACE), stroke, heat stroke or prolonged lack of oxygen example: near drowning. Symptoms can include loss of memory as to the event that caused the concussion, especially persistent disorientation. More severe injury and more ICP if the victim is not fully oriented to person, place, time and event.

Electricity – trauma from electric shock (household current from a loose or bare wire, boom box falls into a pool when not connected to a GFI plug), lightning or problems in the brain

Altitude – high-altitude pulmonary edema (HAPE) (and see high-altitude cerebral edema (HACE) in the Pressure section above)

Toxins – drugs, alcohol, poisons, overdose on common pain relievers, intentional overdose, mushrooms, carbon monoxide, food poisoning, chlorine gas, bites/stings

Salts – low sodium or potassium levels can change the brain’s conductivity

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(Note to on-line users not in my classes: this is a study sheet. It is not complete instruction in first aid or the topic named in the webpage title.)

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