Alcohol Intoxication Signs and 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 have to indicate alcohol intoxication.

Major factors account 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 college student (typically a freshman) who is a novice drinker may get knocked out by a 6-pack of beer. As a person's drinking increases, his or her liver will increase its capacity to metabolize alcohol. Put simply, a heavy drinker will be able to burn off drinks much faster. In addition, a heavy drinker's brain gets used to frequent, even constant, high blood alcohol concentrations (BAC). This habituation in a heavy drinker can backfire if this person suddenly stops drinking. The person may go into withdrawal and develop seizures or a condition called delirium tremens (DTs).
  
  
• Taking drugs. The effects of alcohol are enhanced if someone may be taking other drugs, especially those of the sedative class such as sleeping pills or antianxiety medications. A person who is not habituated to either alcohol or sedatives may cause serious harm, or death, in taking sub-lethal doses of each. Together, they can be a deadly combination. The person may be taking medications prescribed by a doctor or over-the-counter drugs and may not intend for the drugs to enhance the effects of the alcohol.
  
  
• Medical conditions. The presence of a wide variety of medical conditions may affect how someone 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 BAC. 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 2 standard drinks per day), there is a rough correlation between blood alcohol concentration (BAC) and how the person acts.
  
  
  • Blood alcohol concentration. BAC commonly is expressed in milligrams per deciliter (mg/dL). Using this measure, 100 mg/dL roughly is equal to 1 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 drunk when operating a motor vehicle.
    
    
    • To find out more about BAC and how it affects you, go to the Blood Alcohol Educator Web site of the Century Council and the University of Illinois for some startling interactive activities.
      
      
    • The following scale details the expected effects of alcohol at various BACs. 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. Admittedly, such a distinction can be exceedingly difficult for a lay person (such as a police officer) and equally difficult for inexperienced doctors. See, in particular, Advice to Law Enforcement Personnel.