Skip to Substance Use Disorder (SUD) Services site navigationSkip to main content

Absorption Rate Factors

Factors that Affect Intoxication

Many factors influence your body’s ability to absorb and tolerate alcohol. For example, consider the factor of gender:

A 140 lb. Male drinks two drinks in one hour, his blood alcohol level is .038. A 140 lb. female drinks two drinks in one hour and her blood alcohol level is .048.

Male = 185 lbs. Female = 130 lbs.
2 drinks/ 1 hr. = .025 2 drinks/ 1 hr. 053
3 drinks/ 1 hr. = .045 3 drinks/ 1 hr. 088
5 drinks/ 1 hr. =.085 4 drinks/ 2 hrs. = .106


Always eat before drinking, especially foods high in protein. Having food in your stomach will help slow the processing of alcohol. A person who has not eaten will hit a peak BAC typically between 1/2 hour to two hours of drinking. A person who has eaten will hit a peak BAC typically between 1 and 6 hours, depending on the amount of alcohol consumed.

The digestion process itself plays a large factor. For every person, no matter the size, the liver will only digest one standard drink per hour. This is why one drink per hour is recommended. This keeps the liver from being overloaded; it enables a person to maintain a safe BAC and achieve the social relaxation effect most desire.

Strength of Drink

Stronger drinks will result in a higher BAC. Refer to the drink equivalency page for details on alcohol content of standard drinks. Keep in mind that the higher the alcohol content of the drink, the more the alcohol irritates the mucous membranes of the gastrointestinal tract, slowing down the absorption rate of the alcohol.

Body Weight/Body Type

The less you weigh, the more you will be affected by a given amount of alcohol. For people of the same weight, even the same gender, individuals with a lower percentage of body fat will have lower BAC’s than those with a higher percentage of body fat.


Women have less dehydrogenase, the enzyme that breaks down alcohol in the stomach, which contributes to higher BACs than men drinking the same amount of alcohol. Hormone levels also affect the body’s ability to process alcohol, and women will experience higher BACs drinking their regular amount of alcohol right before menstruation. Women tend to have a higher percentage of body fat and a lower percentage of water.


Mood can affect the way one reacts to alcohol. Slight improvements in mood occur at a BAC of approximately (.02-.05). At about a .07, mood begins to deteriorate. Feelings of depression and anxiety prior to drinking can increase or become exaggerated during and after drinking. Stress emotions such as depression, anxiety, and anger can also cause a change in the enzymes in the stomach, thus affecting how one processes alcohol.

Rate of Consumption

The faster a person consumes drinks, the quicker BAC will rise.

Functional Tolerance

Functional tolerance is a decrease in the body’s sensitivity to alcohol’s effects. In other words, a person exhibiting functional tolerance will not seem to be as intoxicated as a person with little or no functional tolerance. This is a behavioral adaptation to the effects of alcohol, and as long as the liver continues to eliminate alcohol at the rate of one drink per hour, it will have no effect on BAC. Being able to “Handle your alcohol” does not have any effect on BAC.

Developing tolerance in upwards of 50%, taking twice the amount to feel the effect, is a sign of a developing problem with alcohol.


Because alcohol is a drug, it should be treated no differently than taking any two prescriptions at the same time. It is important to know the drug interactions and to consult with a physician before mixing any medication with alcohol.

Many times students are unaware of the effects of drinking alcohol on medication. Certain medications, such as antidepressants, should never be mixed with alcohol. Another common mistake when students ask a doctor if they can drink on medication is that an amount is not discussed. Doctor’s often define social use as one to two drinks in an evening. College students often define social use as drinking with a group of people (not necessarily with a limit). Please make sure to discuss specific guidelines with your physician.

An interaction between alcohol and a drug is described as any change in the properties or effects of the drug in the presence of alcohol. Drug interactions may be:

  • Additive: The net effect of the drug taken with alcohol is the sum of their effects.
  • Synergistic: The effect of the drug when combined with alcohol is greater than the sum of their effects.
  • Antagonistic: The effect of the drug is diminished in the presence of alcohol.

For example, certain pain killers, and cold medicines can have a synergistic effect and can multiply the effects of alcohol up to ten times.

Since the liver is responsible for metabolizing drugs other than alcohol, potentially dangerous alcohol-drug interactions can occur in both light and heavy drinkers. If you take prescription or over-the-counter medications, ask your healthcare provider for advice about alcohol intake. Recognize that even herbal medicines and supplements can have adverse interactions with alcohol.


If you are sick, there is a good chance you are dehydrated. This will result in a higher BAC. Dehydration can also make your liver less efficient at eliminating alcohol. You may also be taking medication that can increase the effect of alcohol, leading to problems.


Fatigue causes many of the same symptoms as intoxication, which will magnify the effects of the alcohol. If you are fatigued before drinking, intoxication will intensify the symptoms. When someone is fatigued, the liver is less efficient at processing and/or eliminating alcohol, leading to the experience of a higher-than-normal BAC.

Alcohol Expectancy

Numerous studies over the past decades have determined that a person’s preconceived expectations of alcohol determines the effect more than the amount of alcohol. For example, people who set out to get “drunk” tend to get drunk even on look-a-like drinks.

It is important to make the focus of your evening about friends, socializing, and/or the music rather than about the alcohol.