Sexually transmitted infections are diseases spread by sexual contact. Some of the most common STIs are:

• Chlamydia.
• Genital herpes.
• Genital warts or human papillomavirus (HPV).
• Gonorrhea.
• Hepatitis B.
• Human immunodeficiency virus (HIV), which causes AIDS.
• Syphilis.
• Trichomoniasis.

Left untreated, some STIs can lead to serious problems. For example:

• Certain high-risk types of HPV can cause cervical cancer, penile cancer, and rectal and oral cancer.
• Some STIs can be passed from a pregnant person to the newborn, which can cause serious problems for the baby.
• Chlamydia and gonorrhea can cause pelvic inflammatory disease (PID). PID can lead to serious problems, including not being able to have a baby (infertility).
• Syphilis can cause problems with pregnancy, nerve and heart problems, and death.
• Gonorrhea can increase the risk of bladder cancer in men.

Treatment is available for all sexually transmitted infections (STIs) to relieve symptoms, even if a cure isn't possible.

Some of the most common STIs—chlamydia, gonorrhea, and syphilis—are caused by bacteria and are treated and cured with antibiotics.

STIs caused by viruses, such as genital herpes and genital warts, aren't cured with antibiotics. But treatments are available to relieve symptoms.

Having a routine STI test means getting tested even though you don't have symptoms of an infection. Experts say that certain groups should be routinely tested for certain STIs. Some expert opinions may vary, and your doctor may recommend testing based on your personal history.

What increases your risk of a sexually transmitted infection (STI)?

• Have unprotected vaginal, anal, or oral sex (not using condoms or not using them correctly).
• Are a man (or were assigned male at birth) who has sex with other men (or people assigned male at birth).
• Have a new sex partner or more than one sex partner.
• Have a high-risk sex partner. High-risk partners include people who have more than one sex partner, people who have an STI, and people whose other partners have an STI.
• Are younger than age 25.
• Have a current STI or a history of STIs.
• Have sex while using alcohol or drugs.
• Trade sex for drugs or money.

Chlamydia

The Public Health Agency of Canada (PHAC) recommends a chlamydia test for people who areyounger than 25, pregnant, or at risk for another STI or blood-borne infection.^{footnote 2}

Gonorrhea

If you are younger than 30, your doctor may recommend a gonorrhea test during routine checkups.^{footnote 1}

Syphilis

The PHAC recommends a syphilis test for all pregnant .^{footnote 3}

Tests for STIs are fairly simple. If you have a test for chlamydia or gonorrhea, a nurse or doctor will test for bacteria that cause the infections. You may have a urine test, or the doctor may take a sample of body fluid from the throat, inside the tip of the penis, or inside the rectum or vagina. A gonorrhea culture test also may be done to see if the bacteria are resistant to antibiotics.

A syphilis test looks for antibodies to the bacteria that cause syphilis. Your doctor may do a blood test or may test body fluid or tissue. A follow-up test may be done to confirm the infection.

Getting tested can help find an infection early or when you have no symptoms. This is important so that:

• You can get treatment and avoid long-term problems, such as not being able to have a baby (infertility).
• If you know that you have an STI, you can get treatment and avoid spreading the infection to others.
• If you know that you have an STI, you can tell your sex partner(s) so they can be treated and can avoid spreading the infection.
• If you're pregnant, an STI test can find an infection so you don't spread the infection to your newborn.

• If your test shows that you have an STI, your sex partner(s) will need to know and get tested, which may affect your relationship.
• If you have an STI, your doctor may be required by law to report it to your local health unit. You may be asked for names and addresses of your sex partners.
• You could have a false-positive test result, which shows that you have the disease when you actually don't. This could cause you unneeded worry and treatment.
• For syphilis, you could have a false-negative result, which shows that you don't have the disease when you actually do. (Sometimes the test can't find the antibodies yet.) So you might infect others because you don't think you have the disease.

Your doctor may want you to be tested if:

• You have a high risk for getting an STI.
• You are pregnant.