STI is a quick way of saying sexually transmitted infection. STIs used to be referred to as STDs, or sexually transmitted diseases. To put it simply, these are diseases you get from having sex or sexual contact. STIs can also be transmitted through infected blood or shared needles and syringes.
Certain STIs, including some of the most common STIs in North America such as chlamydia and gonorrhea, can be treated with antibiotics. Some can resolve themselves and disappear, such as genital warts (HPV), and others, especially those caused by viruses instead of bacteria, cannot be cured. Read about the basics of STIs to know which is which.
STI symptoms can vary considerably, depending on the infection. Common STI symptoms include sores around the genitals, burning during urination, and lower abdominal pain.
As the name says, these infections can spread through sexual contact; mostly through unprotected sexual activity. Even with contraception, practicing safer sex might not completely protect someone from being infected. Condoms break. They also expire. Condoms work best when used properly.
STIs may start with sexual contact, but they can spread to affect other parts of your body, too. They can spread to your liver (hepatitis B), your eyes (gonorrhea), and your nerves (syphilis). The infection caused by the human papillomavirus (HPV) has even been linked to cancer of the cervix.
If you think you might have an STI, you need to get tested as soon as possible. If the tests confirm that you have an STI, the next step is to begin available treatment and to talk to your sexual partner(s).