How Alcohol Effects Us: The Biphasic Curve Shows the Pleasure vs Pain Relationship

Most people know that a few drinks make them feel good. So they assume that a lot of drinks will make them feel even better. But that’s not true. Although a few drinks will make them feel better, more will make them feel worse. It’s the biphasic effect or the biphasic effects. And the biphasic curve describes it visually. (Biphasic refers to its two phases or parts.)

The Biphasic Curve

Here’s what happens. People tend to feel better as their blood alcohol concentration (BAC) rises to about .05 (.055 to be exact). That’s the first phase or part of the biphasic curve. If people drink more and their BAC rises above .055, the negative effects of drinking increase and hangovers become worse. Problems associated with drinking too much increase. That’s the second phase. So it’s clearly smart to stop during the first phase and not progress into the second phase.

biphasic curvebiphasic curve

How much does it take to reach a BAC of about .05? The following charts provide guidelines. Remember gender, speed of drinking, food eaten, and some medications effect BAC.

MALE BLOOD ALCOHOL CONCENTRATION GUIDE 2
Number of
Drinks Per Hour
Body Weight in Pounds
110 120 140 160 180 200 220 240
% of Alcohol in Bloodstream
1 .04 .03 .02 .02 .02 .02 .02 .02 Driving
Skills
Impaired
2 .08 .06 .05 .05 .04 .04 .03 .03
3 .11 .09 .08 .07 .06 .06 .05 .05
4 .15 .12 .11 .09 .08 .08 .07 .06
5 .19 .16 .13 .12 .11 .09 .09 .08 Legally Intoxicated in all States
6 .23 .19 .16 .14 .13 .11 .10 .09
7 .26 .22 .19 .16 .15 .13 .12 .11
8 .30 .25 .21 .19 .17 .15 .14 .13
9 .34 .28 .24 .21 .19 .17 .15 .14
10 .31 .27 .23 .21 .19 .17 .16
FEMALE BLOOD ALCOHOL CONCENTRATION GUIDE 2
Number of Drinks Per Hour Body Weight in Pounds
100 120 140 160 180 200 220 240
% of Alcohol in Bloodstream
1 .05 .04 .03 .03 .03 .02 .02 .02 Driving
Skills
Impaired
2 .09 .08 .07 .06 .05 .05 .04 .04
3 .14 .11 .10 .09 .08 .07 .06 .06
4 .18 .15 .13 .11 .10 .09 .08 .08 Legally Intoxicated in all States
5 .23 .19 .16 .14 .13 .11 .10 .09
6 .27 .23 .19 .17 .15 .14 .12 .11
7 .32 .27 .23 .20 .18 .16 .14 .13
8 .36 .30 .26 .23 .20 .18 .17 .15
9 .41 .34 .29 .26 .23 .20 .19 .17
10 .45 .38 .32 .28 .25 .23 .21
How to Maintain a Moderate BAC

Here are some hints for maintaining a moderate blood alcohol concentration.

  • Remember. The typical can of beer, glass of wine, or liquor drink has the same amount of pure alcohol. When it comes to alcohol, a drink is a drink is a drink. They’e all the same to a breathalyzer. For more, visit Standard Drinks and Alcohol Equivalence: Why They’re Important.
  • Know your limit. Most people find that they can consume one drink per hour without any ill effects. Also, experiment with The Drink Wheel.
  • Eat food while you drink. Food helps slow the absorption of alcohol into your body.
  • Sip and savor your drinks.
  • Don’t participate in “chugging” contests or other drinking games.
  • Accept a drink only when you really want one. If someone tries to force a drink on you, ask for a non-alcohol beverage instead. If that doesn’t work, “lose” your drink by setting it down somewhere and leaving it.
  • Alternate beverages. Have a non-alcoholic drink between alcoholic ones. This helps keep your BAC level down. So does spacing out your alcoholic drinks.
  • Keep active. Don’t just sit around and drink. If you stay active you tend to drink less. Also, you tend to be more aware of any effects alcohol may be having on you.
  • Beware of unfamiliar drinks. Some drinks, such as punches, can be deceiving. That’s because the alcoholic content isn’t clear. Therefore, it is difficult to space them properly.
  • Use alcohol carefully in connection with pharmaceuticals. Read the labels carefully. Follow any instructions about drinking alcohol with the medication.

Drinking too much alcohol is never a good idea.

Popular Resources on Drinking

Dasgupta, A. The Science of Drinking: How Alcohol Affects Your Body and Mind. Lanham, MD: Rowman & Littlefield, 2012.

Michael, E. Moder8: Balance for a Better Life. How to Control Your Drinking and Learn to Drink in Moderation. Michael, 2012.

Poikolainen, K. Perfect Drinking and Its Enemies. Minneapolis: Green, 2014.

Turner, C. Can I Keep Drinking? How You can Decide When Enough is Enough. NY: Morgan James, 2017.

Technical Articles on the Biphasic Curve
  • Dudek, B., et al. Genetic analyses of the biphasic nature of the alcohol dose-response curve. Alco Clin Exper Res, 1991, 15(2), 262-269.
  • Earleywine, M. Anticipated biphasic effects of alcohol vary with risk for alcoholism.  Alco Clin Exper Res, 1994, 18(3), 711-714.
  • Earleywine, M. Confirming the factor structure of the Anticipated Biphasic Alcohol Effects Scale. Alco Clin Exper Res, 1994, 18(4), 861-866.
  • Erblich, J., et al. Biphasic stimulant and sedative effects of ethanol. Are children of alcoholics really different? Addict Behav, 2003, 28(6), 1129-1139.
  • Galizio, M. Attenuation of the biphasic effects of ethanol on avoidance extinction by RO 15-4513 in rats. Pharma Biochem  Behav  , 1989, 34(3), 585-589.
  • Giancola, P.R. The Biphasic Effects of Alcohol Metabolism on Human Aggression. Diss Ab Internat: Sec B: Sci Engin. Vol 57(7-B), Jan 1997, pp. 4781.
  • Holdstock, L. and de Wit, H. Individual differences in the biphasic effects of ethanol. Alco Clin Exper Res, 1998, 22(9), 1903-1911.
  • King, A., et al. Biphasic alcohol response differs in heavy versus light drinking. Alco Clin Exper Res, 2002, 26(6), 827-835. Shape of biphasic curve differs between heavy and light drinkers.
  • Martin, C., et al. Development and validation of the Biphasic Alcohol Effects Scale. Alco Clin Exper Res, 1993 17(1), 140-146.
  • Papineau, K., et al. Electrophysiological assessment of the biphasic effects of ethanol in humans. Alco Clin Exper Res, 1998, 22(1), 231-235.
  • Shimosato, K., et al. Biphasic effects of alcohol drinking on methamphetamine metabolism in man. Alco Alco, 1988, 23(5), 351-357.
Notes
  1. Graphics for biphasic curve are from the Alcohol & drug Counseling, Assessment, and Prevention Service at Washington State University. It adapted them from Brief Alcohol Screening and Intervention for College Students (BASICS) by Linda Dimeff et al. It also adapted them from the work of Dr. Pat Fabiano at Western Washington University.

2. Tables adapted from the  National Clearinghouse for Alcohol and Drug Information and the Iowa Alcoholic Beverages Division.