The Brain
It's not fair, but it's a fact: Alcohol's harmful effects hit girls harder than guys. Girls who drink can suffer memory problems, brain damage, and even reduced brain size.

Here's the thing: Pound for pound, a girl's body has less water than a guy's does. Water helps dilute alcohol and the toxins it leaves behind in your body. So, even after your body has processed most of the alcohol you drink, there's still a higher concentration of alcohol and toxins flowing through your blood stream. That means there are also more toxins reaching your brain and other major organs, including the heart, liver, pancreas, and kidneys.

Reproductive System
Drinking also causes some nasty side effects elsewhere. The more you drink, the more likely you are to suffer reproductive problems like menstrual pain, heavy flow, irregular or absent periods-even spontaneous abortions and miscarriages.

Almost everyone wants to lead a fulfilling sex life as an adult, and most girls hope to be a mom eventually. But heavy drinking can put both of these hopes at risk. Alcohol can harm sexual function and prevent (or interfere with) pregnancy. If you do become pregnant (and give birth), your drinking can severely harm your unborn baby. Alcohol can damage your baby's growth and mental abilities.

Other Organs
Unfortunately, girls who drink often suffer more serious alcohol-related health problems than guys-even if they drink less than guys do.

This means that a girl may develop liver damage faster than a guy-even if a guy drinks more alcohol over a longer period of time. As if that wasn't enough, girls may continue to suffer further damage to the liver even after they stop drinking.

Breast Cancer
I know what you're thinking: "Okay, alcohol causes everything. How about cancer?" Well, as a matter of fact, it can. Teen girls who drink display higher levels of estradiol (an estrogen) and testosterone than do girls who don't drink. And, high levels of estrogen are linked to diseases like breast cancer, while high levels of testosterone may be connected to an increased risk of substance abuse.

Teenagers don't really get breast cancer, right? Not usually, but health problems caused by drinking may haunt you later. The death rate from breast cancer is 30% higher among middle-aged and elderly females reporting at least one drink daily, compared to non-drinkers.

Depression
If you're not depressed about alcohol yet, get this: Most people drink to have fun, but the truth is that alcohol is actually a depressant-it often causes depression. Twelve- to sixteen-year-old girls who drink are four times more likely to suffer depression than are girls of the same age who don't drink.

And, teen girls who drink heavily-five or more drinks in a row on at least five different days in the past month-are more likely than boys to say that they drink to escape problems or because of frustration and anger.

Severe cases of depression can even lead to suicide. Among 8th grade girls who drink heavily, 37% report attempting suicide - compared to 11% who do not drink. Drinking isn't always a good time!

Weight Management
You might be thinking: "I'm not worried about cancer or depression." Even if that's true for you, it's important to know that drinking affects something else that's probably important to you right now: your weight. Drinking makes it hard to control your weight. Not only are many alcoholic beverages and mixed drinks high in calories, alcohol makes you hungrier and makes it harder to say "no" to things. So, even if you're not depressed before you start drinking, you might end up with body-image and self-esteem issues after all.

And don't even think about starving yourself to help counter what drinking does to your weight. Going without food before you drink increases your risk of extreme intoxication, which can lead to alcohol poisoning and even death.

Interaction with Medication
You've heard it before, and it's true: Alcohol can interact with a wide variety of drugs, from prescription and over-the-counter medicines to the illegal stuff. If a medication causes drowsiness (like cough and cold medicines and drugs that treat anxiety and depression), alcohol makes it worse. The effects may be hard to predict and impossible to control.

Alcoholism
Decisions you make now can change the rest of your life. You've heard that before, and it's easy to tune it out. But, it's important for you to understand that the younger you start drinking, the more likely you are to become an alcoholic later. Young people who begin drinking before age 15 have a 40% higher risk of becoming alcoholic sometime in their lives than those who wait until age 21 to begin drinking.

The risks for girls are even greater: Female alcoholics are more likely to die than are males, because of their increased risk for suicide, alcohol-related accidents, liver damage, and hepatitis.

You could even be messing up a family you don't even have yet. Daughters of alcoholics are at increased risk for alcoholism. They are also more likely to marry alcoholic men.