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Symptoms and Signs of Alcohol Intoxication

Doctor's Notes on Alcohol Intoxication

Alcohol intoxication occurs when a person consumes quantities of alcohol that result in impairment of mental and physical abilities. Alcohol levels can also be measured in the blood and most states have specific levels of alcohol intoxication at which the driving of a motor vehicle is forbidden.

Symptoms of alcohol intoxication vary widely from person to person and may be affected by prior experience with alcohol, taking medications, certain medical conditions, and blood alcohol concentration. Symptoms of alcohol intoxication may start with loss of emotional restraint, vivaciousness, feeling of warmth, flushing, mild impairment in judgment, slight slurring of speech, loss of control of fine motor movements, confusion when faced with tasks requiring thinking, emotional instability, and inappropriate laughter. As blood alcohol levels rise, symptoms of alcohol intoxication progress to very slurred speech, staggering gait, double vision, lethargy but able to be aroused by voice, difficulty sitting upright in a chair, memory loss, stupor (though able to be aroused only briefly by strong physical stimulus (such as a face slap or deep pinch), and deep snoring. At high blood alcohol levels symptoms of alcohol intoxication include coma, incontinence, low blood pressure, and irregular breathing. Excessively high blood alcohol levels may result in death.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/21/2019

Alcohol Intoxication Symptoms

The effects of alcohol vary widely from person to person. Several factors can account for obvious differences in how certain amounts of alcohol can affect one person more than another. These factors also affect the particular signs and symptoms the person may exhibit to indicate alcohol intoxication.

Major factors accounting for this variation in signs and symptoms:

  • Prior experience with alcohol: A longtime, heavy drinker may achieve blood alcohol concentration levels that would kill the average casual drinker. Conversely, a novice drinker may have severe symptoms with the ingestion of a moderate amount of alcohol. As a person's drinking increases, his/her liver will increase its capacity to metabolize alcohol. In addition, the brain of a heavy drinker becomes used to frequent, even constant, high blood alcohol concentrations. This habituation in a heavy drinker can backfire if this person suddenly stops drinking. The person may go into alcohol withdrawal and develop seizures or a condition called delirium tremens (DTs).
  • Taking medications: The effects of alcohol are enhanced if a person is taking other prescription medications, especially those of the sedative class such as sleeping pills or anti-anxiety medications. A person who is not habituated to either alcohol or sedatives may experience serious harm, or even death, if taking prescribed doses. Together, they can be a deadly combination. A person may be taking medications prescribed by a doctor or over-the-counter medications, and may not know about these unintended consequences.
  • Medical conditions: The presence of a wide variety of medical conditions may affect how a person reacts to alcohol.
  • Smell of alcohol on the breath: There is a very poor correlation between the strength of the smell of alcohol on the breath and the blood alcohol concentration. Pure alcohol has very little smell. It is the metabolism of other substances in alcoholic beverages that produces most of the smell. This explains why a person who drinks large amounts of high-proof vodka (a more pure form of alcohol) may have only a faint smell of alcohol on the breath. On the other hand, a person who drinks a modest amount of beer may have a strong smell of alcohol on the breath.
  • Scale of effects: In the average social drinker (defined as someone who drinks no more than two standard drinks per day), there is a rough correlation between blood alcohol concentration and how the person acts.
  • Blood alcohol concentration. Blood alcohol concentration commonly is expressed in milligrams per deciliter (mg/dL). Using this measure, 100 mg/dL roughly is equal to one part alcohol in 1000 parts of water (or blood). Consequently, 100 mg/dL would be equal to a 0.1% concentration. In most states, 100 mg/dL represents the threshold concentration above which a person is legally intoxicated when operating a motor vehicle.
    • To find out more about blood alcohol concentration and how it affects a person, go to the Blood Alcohol Educator Web site of the Century Council and the University of Illinois.
    • TThe following scale details the expected effects of alcohol at various blood alcohol concentrations. There is a tremendous variation from person to person, and not all people exhibit all the effects. This scale would apply to a typical social drinker:
      • 50 mg/dL: Loss of emotional restraint, vivaciousness, feeling of warmth, flushing of skin, mild impairment of judgment
      • 100 mg/dL: Slight slurring of speech, loss of control of fine motor movements (such as writing), confusion when faced with tasks requiring thinking, emotionally unstable, inappropriate laughter
      • 200 mg/dL: Very slurred speech, staggering gait, double vision, lethargic but able to be aroused by voice, difficulty sitting upright in a chair, memory loss
      • 300 mg/dL: Stuporous, able to be aroused only briefly by strong physical stimulus (such as a face slap or deep pinch), deep snoring
      • 400 mg/dL: Comatose, not able to be aroused, incontinent (wets self), low blood pressure, irregular breathing
      • 500 mg/dL: Death possible, either from cessation of breathing, excessively low blood pressure, or vomit entering the lungs without the presence of the protective reflex to cough it out
  • Other conditions that look like alcohol intoxication: It is important to recognize the symptoms of alcohol intoxication not only to confirm the presence and severity of the alcohol effect, but also to be able to differentiate the symptoms from other conditions that may coexist, mimic, or mask the symptoms of alcohol intoxication.

Alcohol Intoxication Causes

Alcohol is a generic term for ethanol, which is a particular type of alcohol produced by the fermentation of many foodstuffs - most commonly barley, hops, and grapes. Other types of alcohol commonly available such as methanol (common in glass cleaners), isopropyl alcohol (rubbing alcohol), and ethylene glycol (automobile antifreeze solution) are highly poisonous when swallowed, even in small quantities.

Ethanol produces intoxication because of its depressive effects on various areas of the brain causing the following physical and mental impairments in a progressive order as the persons alcohol level increases (the person becomes more and more intoxicated).

  • Disinhibition of normal social functioning
  • Euphoria (excessive talking, showing off)
  • Ataxia (uncoordinated gait-walking)
  • Poor judgment
  • Loss of memory
  • Slurred speech
  • Worsening ataxia
  • Vomiting
  • Confusion and disorientation
  • Progressive lethargy and coma
  • Ultimately the shutdown of the respiratory centers and death

What happens to brain function: Alcohol increases the effect of the body's naturally occurring neurotransmitter GABA (gamma amino butyric acid). Neurotransmitters are substances that chemically connect the signals from one nerve to the next allowing a signal to flow along a neural pathway. An inhibitory neurotransmitter (alcohol) reduces this signal flow in the brain. This explains how alcohol depresses both a person's mental and physical activities. By way of comparison, cocaine does the opposite by producing a general excitatory effect on the nervous system.

Available forms and measurement: A standard "drink" of ethanol consists of 10 grams. This amount is equal to:

  • Ten ounces (300 cc) of regular beer (5% alcohol content);
  • Three-and-a-quarter ounces of wine (12% alcohol content); or
  • One ounce of hard liquor (40% alcohol content, 80 "proof").

Absorption: Approximately 20% of ethanol is absorbed into the bloodstream directly from the stomach, and 80% from the small intestine. Consequently, the longer the ethanol/alcohol remains in the stomach, the slower it will be absorbed and the lower the peak in the blood alcohol concentration (BAC).

  • This explains the apparent sobering effect of food, which slows the process of emptying the stomach contents, slows the absorption of alcohol, and thus reduces the peak blood alcohol concentration reached.
  • When alcohol is consumed with food, absorption generally is complete in 1-3 hours during which time the blood alcohol concentration will peak. If no further alcohol is consumed, sobering up will follow this peak level of blood alcohol concentration.

Distribution: Ethanol is highly soluble in water and is absorbed much less in fat. So alcohol tends to distribute itself mostly in tissues rich in water (muscle) instead of those rich in fat.

  • Two people may weigh the same, yet their bodies may have different proportions of tissue containing water and fat. Think of a tall, thin person and a short, obese person who both weigh 150 pounds. The short, obese person will have more fat and less water making up his/her body than the tall, thin person. If both people, in this example, consume the same amount of alcohol, the short, obese person will end up with a higher blood alcohol concentration. This is because the alcohol he drank was spread into a smaller water "space."
  • Women's bodies, on average, have more fat and less water than men's bodies. Using the same logic, this means that a woman will reach a higher blood alcohol concentration than a man of the same weight when both drink the same amount of alcohol.

Metabolism (elimination): Metabolism is the method by which the body processes alcohol and everything else a person eats or drinks. Some of the alcohol is converted to other substances (such as fat, as in "beer belly"). Some is burned as energy and converted to water and carbon dioxide. A small amount is excreted unchanged in the breath and urine. The liver metabolizes about 90% of the ethanol. The lungs excrete about 5% during exhalation (breathing out). Alcohol excretion by the lungs forms the basis for Breathalyzer testing. Another 5% is excreted into the urine.

  • The average person metabolizes about one standard drink (10 grams) per hour.
  • Heavy drinkers have more active livers ,and may be able to metabolize up to three drinks per hour.
  • People with liver diseases will metabolize less than one drink per hour. In many chronic alcoholics, the liver becomes ineffective and can no longer metabolize alcohol, or anything else, efficiently. This is known as alcoholic cirrhosis.
  • In alcoholic cirrhosis, the liver cells become badly scarred. This scarring has the effect of blocking blood flow through the liver, impeding exchange of metabolic chemicals into and out of the liver cells, and damaging the cells' ability to function.

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Alcohol consumption can cause numerous diseases. Many people know that heavy drinking can lead to cirrhosis of the liver and is a leading cause of automobile accidents. But did you know chronic drinking could also lead to cancer and heart attack? Read on to find out consequences of heavy drinking.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.