Does an STD Show Up in a Blood Test?

Does an STD Show Up in a Blood Test

Some STIs don’t cause symptoms and may not show up on regular blood tests. To test for these infections, a doctor or APP pricks the arm and takes a blood sample or swabs discharge from a sore on the penis, vagina, urethra, or cervix.

Some STIs have a long incubation period, meaning they won’t show up in a test until it is too late. This is why it is important to get tested for STIs often.


Chlamydia (Chlamydia trachomatis) is a bacteria that most commonly spreads through unprotected vaginal, oral or anal sex, or by using a toy in sexual intercourse. The infection can also be transmitted to a pregnant woman and lead to serious complications with pregnancy, including infertility. Symptoms of chlamydia may include discharge from the vagina or penis; pain during sexual intercourse; or a swelling in the vulva, anus or testicles (epididymitis).

Chlamydia can be detected with a simple blood or urine test. For a urine test, you will pee into a cup that’s sent to a lab to be tested for the bacteria. If you get a positive result, your health care provider will prescribe antibiotics to treat the infection. You’ll need to continue taking the medication until you’re cured, and should tell all of your sexual partners that you have chlamydia so they can get tested and treated, too. You’ll need to get another test 3 months after treatment to ensure that the infection is gone.


Gonorrhea is caused by the Neisseria gonorrhoea bacteria and can be spread through unprotected vaginal, oral or anal sex. The bacterium can also infect the urethra, throat and eyes (when semen comes into contact with them).

A urine test is the most common way to diagnose gonorrhea. A swab can also be taken from the cervix, urethra, throat or anus and cultured to see if gonorrhea is growing. This method can be more accurate than a urine test.

Women with untreated gonorrhea may develop pelvic inflammatory disease (PID). This infection can cause damage to the uterus and fallopian tubes, leading to infertility. In men, gonorrhea can spread to the tubes that carry semen, causing a painful condition called epididymitis. Rarely, gonorrhea can also spread to the blood and joints, making it life-threatening. If you are diagnosed with gonorrhea, healthcare professionals will ask for the names and contact information of your sexual partners, so they can be informed anonymously that they need to get tested and treated.

Hepatitis B

Hepatitis B is a viral infection that can cause inflammation of the liver. This infection spreads through contact with blood and other bodily fluids. Symptoms can take 1-9 weeks to appear. A hepatitis B test can detect the presence of the virus in the body up to 1-9 weeks after someone has come into contact with it.

A hepatitis B infection can be acute or chronic. It can lead to severe liver diseases, including cirrhosis and liver cancer. The hepatitis B virus can also be transmitted during unprotected sex, from a mother to her baby during childbirth, through sharing contaminated needles for intravenous drug use, and by getting a tattoo or piercing that uses an unsterilized needle.

NYU Langone recommends practicing safe sex by using a condom and not sharing personal items like toothbrushes, razors, nail clippers and body jewelry with anyone. It is less common to get hepatitis B than hepatitis C due to the availability of a vaccine for it.

Human Papillomavirus

Human papillomavirus, or HPV, is a family of over 100 viruses that can affect your hands, feet, face and other parts of the body. Most genital HPV strains are harmless and clear up on their own. There are also some types that can lead to cancer in your vulva, vagina, anus and penis.

You get HPV by sexual skin-to-skin contact with someone who has it. There are lots of different types of HPV infections, but two in particular (types 6 and 11) cause most genital warts. These are referred to as low-risk HPV.

However, some kinds of HPV can cause pre-cancerous changes in the cervix that can lead to cervical cancer over time. It’s important for women to get regular Pap tests, which can pick up these changes. You can also find out if you have genital HPV by using an at-home test service that provides the same lab tests used by doctors or clinics.

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