You can get a bacterial infection of chlamydia, syphilis or gonorrhea in your mouth and/or throat and could develop genital warts in the mouth.

Herpes is commonly passed between the genitals and the mouth, and HIV can be passed through cuts in the mouth or small abrasions

Pieces of latex or plastic wrap over the vagina or condoms over the penis can be used as barriers during Oral sex . For more on using protection during Oral sex, there’s great advice on the Palo Alto website.

• Stick with one partner. Don’t have sexual contact with anyone but your partner to avoid exposure to an STD that, in turn, you could spread between partners.
• Be aware about drugs and alcohol. They may affect your ability to make good decisions and lead to sex that you might regret or were pressured into because you weren’t thinking properly. You might not choose your partner as carefully. You may also forget to use condoms or use them incorrectly.

According to CDC.gov:

Hepatitis B can be transmitted through sexual contact when blood, semen, or another body fluid from a person infected with the Hepatitis B virus enters the body of someone who is not infected. It can also be transmitted by sharing needles, syringes, or other drug-injection equipment; or from mother to baby at birth. It develops in the liver first.

Hepatitis C Although the risk of transmission from sexual contact is believed to be low. The risk increases for people who have multiple sex partners, have a sexually transmitted disease, engage in rough sex, or are infected with HIV.

An STI is a sexually transmitted infection, an STD is a sexually transmitted disease.

• Use a polyurethane condom if you are allergic to latex. Regardless of the material, choose the appropriate size for the right coverage.
• Avoid condoms with the spermicide nonoxynol-9, once thought to help prevent HIV transmission. Research has shown that it irritates vaginal tissue and can create small tears.
• Use appropriate barriers for intimacy other than intercourse, such as condoms on dildos and other penetrative sex toys, latex gloves for digital penetration and a sheet of latex called a dental dam that’s placed over a woman’s genitals during Oral sex.

Some infections can be spread by contact with surrounding skin if it’s not covered—pubic lice and scabies, genital warts and herpes for instance are spread by close skin-to-skin contact. Still, condoms do offer the best available protection when used correctly.

Fyi, in India condoms are referred to as playguard.

• Do not douche or wash inside the vagina because this can push any sperm and bacteria high into your vagina, which is more likely to result in a pregnancy or Sexually Transmitted Disease.

You may need to get emergency contraception within the first 72 hours after a condom breaks if you are not using any other form. Have a sexual health check-up within two weeks after the condom breaks or sooner if you have any symptoms or concerns.

If You Were Receiving
ANAL SEX

• Sit on the toilet and bear down to remove as much sperm as possible.
• Do not douche or wash inside your anus because this can create tears and increase the likelihood of STD transmission.
• Have a sexual health check-up within two weeks after the condom breaks or sooner if you have any symptoms or concerns.

If You Were Giving
ORAL SEX:

• Spit out any semen quickly or swallow it immediately—do not let it stay in your mouth.
• Rinse and spit using water.
• Do not brush or floss your teeth for at least one hour.
• Have a sexual health check-up including throat swabs within two weeks after the condom breaks or sooner if you have any symptoms or concerns.