STIs often asymptomatic

STIs often have no signs or symptoms (asymptomatic). Even with no symptoms, however, you can pass the infection to your sex partners. So it's important to use protection, such as a condom, during sex. And visit your doctor regularly for STI screening, so you can identify and treat an infection before you can pass it on.

Some of the following diseases, such as hepatitis, can be transmitted without sexual contact, by coming into contact with an infected person's blood. Others, such as gonorrhea, can only be transmitted through sexual contact.