Hesperian Health Guides

Do I Have a Sexually Transmitted Infection?

Signs of STIs include discharge, pain, and sores in the genitals. But many STIs cause no signs. Even without signs, STIs can pass from one person to another during sex without condoms. Tests of samples of blood, urine, or swabbing the affected part of the body are used to know which STI a person has. Tests are also part of regular health care to find and treat STIs that cause no signs.

health worker taking a blood sample
A blood test can check for some STIs.

Testing for STIs

To test for STIs, the health worker takes a sample from the person and may use a test kit or look for the infection using a microscope. Types of STI tests include:

  • Using a swab on the genital area gives a sample to test for chlamydia, gonorrhea, genital herpes, chancroid, or trichomonas. Swabbing the inside of the mouth can test for HIV. Swabbing the throat or anus is sometimes needed to test for a STI from oral or anal sex. Swabbing the cervix can test for HPV.
  • Urine tests can detect chlamydia and gonorrhea.
  • Blood tests can detect syphilis, genital herpes, hepatitis, and HIV.

Testing for STIs is a good idea for all people who are sexually active. How often can depend on if you have a new partner, more than one partner, or have a reason to think you may have a STI. If you are pregnant, it is common to test for STIs that can harm the baby or cause harm to you.

If you have a STI, get tested as well for other common STIs because 2 or more are often passed at the same time.

Signs that could be a STI

Pain or unusual discharge from the vagina in women
Is there pain in the lower belly or pain during sex?
This could be pelvic inflammatory disease (PID).
Is there pain or burning while urinating?
This could be a urinary infection, not a STI (see Difficulties With Urinating, in development). Or, this could be trichomonas, gonorrhea, or chlamydia.
Is the discharge white or gray and smell bad or like fish, especially after sex?
This could be bacterial vaginosis. Or less commonly, trichomonas.
Is the discharge yellow or green?
This could be gonorrhea or chlamydia. It could also be an infection of trichomonas.
Is the discharge white, looks like cottage cheese or buttermilk, and smells like mold, mildew or baking bread?
This could be a yeast infection, which is not a STI.

Pain or unusual discharge from the penis in men
Is there pain or burning while urinating?
This could be gonorrhea or chlamydia. Or less commonly, trichomonas.
Is there pain or painful swelling in the testicles?
This could be gonorrhea or chlamydia. Other causes also need treatment so talk to a health worker.
Is there discharge from the penis that just drips and drips?
This could be gonorrhea

Ulcers, sores and growths on the genitals or near the anus
Is there a painless open sore, with raised edges?
This could be syphilis.
Is it 1 or more painful sores that are puffy and bleed easily?
This could be chancroid.
Are there small blisters that burst and form painful, open sores?
This could be herpes.

Other signs in men or women in genitals or anus
Itching of the anus or pain passing stool can sometimes be the sign of a STI. Also if you notice discharge coming out of your anus or that it is slippery when you wipe your bottom, this could be a sign of gonorrhea, or chlamydia.
Get medical help for signs of a more serious infection that include discharge from the vagina, penis or anus that is bloody or brown.

Itching of the genitals
Itching around the opening of the vagina, on the thighs or where urine comes out could be yeast or, for women, a sign of trichomonas.

Itchy genitals could also be pubic lice or scabies, which are very tiny bugs that live on the skin, treated with medicines put on the skin, such as those with permethrin (see Skin Problems, in development). Scabies are spread easily between family members, are common in children, and affect many parts of the body.

Itching can also be caused by soaps, perfumes, or chemicals put on or in the genitals. Rinse the outside of the genitals with plain water to see if the itching goes away.

This page was updated:16 Oct 2019