Experts say adolescents should be made aware of how using drugs and alcohol can lead to sexual activities that may change their lives forever.

While drinking and having sex may be unofficially authorized milestones in the typical American teen’s coming of age, a new study reveals that more and more adolescents are experimenting with both, leaving themselves susceptible to pregnancy, disease and violence.

In a random survey of 1,200 adolescents and young adults ages 13 to 24 throughout the United States, the Kaiser Family Foundation found that 81 percent reported that they have had intercourse, and 50 percent agreed that “people their age” mix alcohol and drugs “a lot.”

Experts say these findings, to be presented today at a substance abuse and sexual behavior conference at Columbia University in New York, are so disturbing because drugs and alcohol can significantly compromise one’s judgment and put teens into high-risk situations.

“We knew that teenagers were doing this, but frankly it is a bit shocking that the numbers were so high,” said Dr. Timothy Johnson, ABCNEWS’ medical editor.

Unintended and Unprotected Sex

Drinking and doing drugs often leads young people to engage in more sexual activity than they intended to partake in, and more importantly, to unprotected sex, says Joseph Califano, former U.S. secretary of health, education and welfare and president of The National Center on Addiction and Substance Abuse at Columbia.

Overall, 29 percent of sexually active 15- to 24-year-olds surveyed say that they have “done more” sexually than they had planned while drinking or using drugs, and 74 percent say their peers “often do not use condoms when they are drinking or using drugs.”

Considering the high rate of alcohol use among high-schoolers, it is no wonder the Centers for Disease Control reports that almost 1 million unwanted teenage pregnancies occur every year, and one in every three sexually active people in the United States will contract a sexually transmitted disease by the age of 24. This includes everything from genital warts to the life-threatening HIV.

In addition, drinking has been shown to play a predominant role in sexual violence, with more than half of college campus rapes including alcohol use by either the victim, the attacker, or both. Experts believe alcohol causes people to both misread and missend sexual signals, and also can create situations where people are vulnerable to attack.

Mix Your Messages

So what can concerned parents do to help their teens avoid these hazards? Califano says the best thing you can do is get involved.

“Parental engagement is probably the most effective way to reduce the risk of smoking, drinking, and doing drugs, and the overwhelming majority of research studies show that teens who are close to their parents are more likely to remain sexually abstinent and postpone intercourse, more likely to use contraceptives if they are sexually active, more likely to have fewer sexual partners, and less likely to become pregnant,” says Califano.

And whether you believe that abstinence is a moral imperative, or if you think that sexual activity is simply a rite of passage for all teens, Califano emphasizes that “everyone must drive home the very real dangers of mixing alcohol, drugs, and sex — pregnancy, HIV, STDs, and rape.”

He also strongly recommends that when having the “big talks” with your kids, emphasize the connection between drinking and sex. Because even though your teen may feel strongly about “how far they will go,” morals and intentions can be easily led astray after a couple of beers at a party.

“Make sure that every time you talk to your kids about sex, you also talk about drugs and alcohol, and every time you talk to them about drugs and alcohol, you talk to them about sex,” Califano advises. He says kids should learn how the topics are connected, so they are better equipped to deal with challenging situations when they arise.

Experts also suggest keeping an eye on the television shows your children watch, the music they listen to, and the Web sites they visit, because staying aware of outside influences helps parents become better equipped, as well.