It depends. You should get tested right away if you have any of these symptoms of a sexually transmitted disease (STD):
Girls:
- Pain or burning when you pee or have sex
- Bleeding between periods
- Red, irritated, or swollen genital skin
- Unusual discharge from the vagina
- Unexplained bleeding during intercourse
- Bumps, sores, or rashes in the genital area
Boys:
- Pain or burning when you pee or have sex
- Red, irritated, or swollen genital skin
- Unusual discharge from the penis
- Bumps, sores, or rashes in the genital area
ALSO, Since many STDs have no symptoms, you don’t want to take any chances, so regular screening is recommended for all sexually active adults, even if no symptoms are present. The longer an STD goes untreated, the more damage it can do to you and others. STDs can’t be “cured” on their own; they must be treated. For example, a herpes sore may come and go, but the herpes virus stays in an infected person’s body and can still infect a partner, even when the sore isn’t present.
If you have no symptoms, but have had oral, vaginal, or anal sex without using condoms
—or you've had sex with more than one partner
—you should get tested once a year. (A Pap smear is the only screening test for an HPV infection of the cervix.)
Your chances of getting an STD increase when you’ve had unprotected sex or sex with multiple partners. If you continue having sex with multiple partners, you should get tested every six months.
And if you’re having unprotected sex, you should take steps to protect each other, such as use a condom, get tested and/or be monogamous. It’s also a good idea for partners to get tested before having sex with each other. This will help them feel more comfortable.
If you're in a committed relationship and use condoms, get tested once a year. Even though you totally trust your partner, people sometimes make mistakes and cheat. And they often keep it secret, because they want to keep the relationship. So, always be safe.
After getting tested, it's smart to continue using condoms, even if you're in a steady relationship or using another type of hormonal birth control.
Hope this helps, please feel free to let me know if you have any other questions about testing or exposure/transmission risks.