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Sexually Transmitted Infection (STI) Tests
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Sexually Transmitted Infection (STI) Tests

STI tests are essential tools for detecting infections passed through sexual contact, allowing for timely treatment and the prevention of long-term health complications.

What are STI tests?

Sexually transmitted infections (STIs), also known as STDs, are infections spread through sexual contact, including vaginal, oral, or anal sex. Some, such as herpes and HPV (human papillomavirus), are spread via skin-to-skin contact. Other transmission routes include kissing, pregnancy/childbirth, breastfeeding, blood transfusions, or sharing needles.

Common STIs include chlamydia, gonorrhea, genital herpes, HIV, and HPV. If left untreated, these can lead to severe health issues, including infertility, brain damage, and even death.

Why do I need an STI test?

Because many STIs cause no symptoms, you can be infected or spread an infection without knowing it. Screening is recommended for anyone who is sexually active. Specific testing guidelines include:

  • Sexually active women under 25: Annual chlamydia and gonorrhea testing.
  • Women 21–30: Regular Pap smears to check for cervical cell changes caused by HPV.
  • Pregnant individuals: Routine screening for HIV, hepatitis B, chlamydia, and syphilis.
  • High-risk groups: Individuals with multiple partners, men who have sex with men, people with HIV, and those who use injectable drugs should consult their provider about regular, frequent testing.

You should seek testing if you experience symptoms such as painful urination, unusual discharge, sores or bumps in the genital/rectal area, or pelvic pain.

What happens during an STI test?

Depending on the suspected infection, your provider may use one of the following methods:

  • Blood tests: Used for syphilis, HIV, hepatitis B, and sometimes herpes.
  • Urine tests: Used for trichomoniasis, chlamydia, and sometimes gonorrhea.
  • Swab tests: Used for HPV, chlamydia, gonorrhea, and herpes by collecting samples from the site of infection.
  • Lumbar puncture: Rarely used, but may be ordered for advanced syphilis or herpes affecting the brain or spinal cord.

What do the results mean?

The test results indicate whether you have an STI. If positive, it is critical to follow your provider’s treatment plan and inform your sexual partners so they can be tested and treated, preventing further spread and complications.

Prevention

The only way to completely prevent STIs is by not having sex. You can lower your risk by:

  • Getting tested with your partner before sexual activity.
  • Reducing the number of sexual partners.
  • Maintaining a long-term, mutually monogamous relationship with a partner who has tested negative.
  • Using latex or polyurethane condoms correctly every time.
  • Getting vaccinated against HPV and hepatitis B.

Frequently Asked Questions

If you and your partner have both been tested and are mutually monogamous, you may not need frequent testing. However, if you are not certain of your partner's status, or if you have had other partners recently, annual testing is a common baseline recommendation. For sexually active individuals under 25, or those with new or multiple partners, more frequent testing (every 3 to 6 months) is often advised. Always discuss your specific risk factors with your provider to determine the appropriate testing schedule.
Yes, many STIs can be transmitted through oral sex. This includes herpes, gonorrhea, chlamydia, and syphilis. While the risk of transmitting HIV through oral sex is lower than through vaginal or anal sex, it is still possible, particularly if there are open sores or bleeding gums. Because oral transmission is a valid route for several infections, it is important to include a history of oral sexual activity when discussing your risk factors with a healthcare provider to ensure you are tested for the appropriate infections.
For most standard STI tests, such as urine samples for chlamydia or gonorrhea, or blood draws for HIV and syphilis, there are no dietary restrictions. You do not need to fast. However, for urine tests, it is often recommended to use the first part of your morning urine stream, as it is more concentrated and likely to yield accurate results. If you are undergoing a specific type of swab test, follow your provider's instructions regarding hygiene or medication use prior to the appointment.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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