What behaviors do teens display that put them at higher risk for contracting an STD?

* Unprotected sex. Having sex without a condom or other barrier method is the most common way to get an STD.

* Multiple sexual partners. The more sexual partners someone has, the greater their risk of getting an STD.

* Younger age of first sex. Teens who start having sex at a younger age are more likely to get an STD.

* Alcohol and drug use. Alcohol and drug use can impair judgment and lead to risky sexual behavior, such as having unprotected sex.

* A history of STDs. Teens who have had an STD in the past are more likely to get an STD again.

* Not getting vaccinated. There are vaccines available to protect against some STDs, such as hepatitis B and human papillomavirus (HPV). Teens should get these vaccines as soon as they are recommended by their doctor.