Blood Alcohol Content (BAC) is a measure of alcohol concentration in a person’s bloodstream. The more a person drinks, the higher their BAC and the more they experience alcohol-related impairments. The following table shows the behavioral, physical, and mental changes brought on by alcohol at various BAC levels:
Progressive Effects of Alcohol with rising BAC levels
| Blood Alcohol Concentration |
Changes in Feelings and Personality |
Physical and Mental Impairments |
| 0.01 — 0.06 | Relaxation Sense of Well-being Loss of Inhibition Lowered Alertness Joyous |
Thought Judgment Coordination Concentration |
| 0.06 — 0.10 | Blunted Feelings Disinhibition Extroversion Impaired Sexual Pleasure |
Reflexes Impaired Reasoning Depth Perception Distance Acuity Peripheral Vision Glare Recovery |
| 0.11 — 0.20 | Over-Expression Emotional Swings Angry or Sad Boisterous |
Reaction Time Gross Motor Control Staggering Slurred Speech |
| 0.21 — 0.29 | Stupor Lose Understanding Impaired Sensations |
Severe Motor Impairment Loss of Consciousness Memory Blackout |
| 0.30 — 0.39 | Severe Depression Unconsciousness Death Possible |
Bladder Function Breathing Heart Rate |
| => 0.40 | Unconsciousness Death |
Breathing Heart Rate |
BAC levels can be accurately measured through blood, breath, or urine tests. Currently, the legal limit to drive in the U.S. is .08 for individuals over the age of 21. That limit is similar to those used in other states, but there is some variation.
How many drinks for a BAC of .08?
The answer to this question is a little more complicated than it seems. Alcohol affects everyone differently. In general, smaller individuals reach higher BAC levels more quickly than larger individuals, fatter individuals reach higher levels more quickly than muscular individuals, and women reach higher levels more quickly than men. These factors are all related to the amount of water present in the body. The more water a person has in their body, the more diluted the alcohol will be in their blood. (smaller individuals have less water than bigger people, fatty tissue has less water than muscle, and women typically have a higher % of body fat than men).
Chronic drinkers can develop a tolerance to alcohol, allowing them to metabolize alcohol more quickly and giving them added resistance to the functional impairments of alcohol.
Furthermore, alcohol can affect the same person differently under different circumstances. Eating before drinking can delay alcohol absorption and reduce a person’s peak BAC levels by as much as 40%. Exhaustion, illness, and dehydration impair a person’s ability to metabolize alcohol, promoting higher BAC. Depressed mood and stress can also magnify the effects of alcohol. Finally, medications can react with alcohol, potentially causing serious health complications.
You’ve had too many – can you lower BAC?
Contrary to popular belief, there is no magic food or drink that can lower your BAC levels. Exercising and taking a cold shower will also do nothing to lower BAC. BAC levels will only decrease with time. On average, a person metabolizes alcohol at a rate of one drink (0.5 oz alcohol) per hour. Spacing out drinks is a good way to manage BAC levels as it gives your body time to metabolize alcohol while delaying further increases in BAC.
Understanding your body is the first step towards preventing dangerous BAC levels. Plan ahead make sure you don’t ruin your night or someone else’s by drinking more than you can handle.
Additional Resources:
Check out the Virtual Bar at www.b4udrink.org for a really fun way to learn about your own limits!