Microscopic image of blood cells during a CBC blood test

Does A CBC Blood Test Show STDs?

Written on December 20, 2023 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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If you have recently gotten lab work completed, you may have gotten a complete blood count (CBC), which is a fairly standard lab order that screens for several values. Some people may wonder, does a CBC blood test show sexually transmitted diseases (STDs)? Read this article for everything you need to know.

What Is A CBC?

A CBC is a blood test that can screen for several blood values and potential health conditions.[1] Some of these measures include levels of red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. During a CBC, a healthcare provider will take your blood and send it to a lab for testing. While it is typical for CBCs to be part of a standard physical, a healthcare provider may also order a CBC if you are trying to rule out certain health conditions or are presenting with particular symptoms.

Some conditions that a CBC can screen for include [2]:

  • Anemia (low levels of red blood cells that carry oxygen through the body)
  • Bone marrow disorders
  • Infections that would affect levels of white blood cell counts
  • Certain types of cancers
  • Certain vitamin and/or nutrient deficiencies

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Does A CBC Blood Test Screen For STDs?

The short answer is, no, typical CBC blood tests do not usually show indication of infection with an STD. This is why you should undergo regular STD testing if you are sexually active, especially if you or someone you are intimate with has had many partners.

If you want to be tested for STDs, a healthcare provider can order a blood test as well as other types of tests, including urine, cells, fluid, or saliva-based tests.[3] However, these blood tests are not part of a typical CBC. Blood tests that are used to screen for STDs typically are used to screen for specific infections like cytomegalovirus, hepatitis, herpes, human immunodeficiency virus (HIV), or syphilis.[3] In addition, not all STDs can be detected via blood tests.

Because CBCs are a fairly normal part of yearly exams for many people and because they do not typically screen for STDs, you should ask a healthcare provider to test you for STDs separately. A healthcare provider will then likely ask you a series of questions to screen for which STDs are most appropriate to test you for.[4] A healthcare provider may ask you questions regarding symptoms, your sexual history, the sexual history of your partners, the kind of sex you are having, and protection methods to determine which STDs to test you for.[4]

What To Do If You Receive A Positive STD Test

If you receive a positive STD test, a healthcare provider can inform you about your next steps and the appropriate treatment regimen. STDs are very common, affecting millions of people around the world. Generally, the following steps are recommended if you test positive for an STD via a blood test or other testing measure [5]:

  • Stop having sex until you have received treatment or a negative STD test.
  • Consult a qualified healthcare provider for next steps in treating the STD.
  • Begin treatment for the STD. There are several curable STDs, like chlamydia, gonorrhea, syphilis, and trichomoniasis. If you seek and follow the appropriate treatment, these STDs should go away with antibiotics. It is important to continue to take the antibiotics for the entire duration recommended even if symptoms begin to improve.
  • If you are currently being treated for an STD, refrain from all sexual activity until you have finished the course of medication.
  • Inform any sexual partners that you tested positive for an STD so that they can undergo testing and treatment if needed.
  • If you test positive with an incurable STD, seeking and beginning treatment is equally as important. Many people live with incurable STDs, like herpes, HIV, genital warts, and hepatitis B. Undergoing the appropriate treatment will allow you to continue to lead a healthy life.
  • Adopt a safe sex plan moving forward. Getting diagnosed with an STD is not fun, and you should prioritize safe sex moving forward by using protection, getting tested frequently, and ensuring that those whom you are intimate with are safe as well.

Support Your Sexual Health With Everlywell

At Everlywell, we combine the best in modernized, rigorous lab testing with easy-to-access, at-home medicine. We provide a range of blood tests, including several sexual health tests, that you can take from the comfort of your home. Your results will be analyzed in CLIA-certified labs and an experienced healthcare provider will deliver your results. You can also connect with a healthcare provider online with personal telehealth visits. Take control of your health today with Everlywell.

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  1. Complete blood count (CBC). Mayo Clinic. https://www.mayoclinic.org/tests-procedures/complete-blood-count/about/pac-20384919. Published January 14, 2023. Accessed December 12, 2023.
  2. Complete blood count. Cleveland Clinic. https://my.clevelandclinic.org/health/diagnostics/4053-complete-blood-count. Last reviewed March 2, 2021. Accessed December 12, 2023.
  3. How does a doctor test for STDs? Planned Parenthood. https://www.plannedparenthood.org/blog/how-does-a-doctor-test-for-stds. Published August 10, 2023. Accessed December 12, 2023.
  4. How Does STD Testing Work? | information About STD Tests. Planned Parenthood. https://www.plannedparenthood.org/learn/stds-hiv-safer-sex/get-tested/how-does-std-testing-work. Accessed December 12, 2023.
  5. What should I do if I get an STI? Planned Parenthood. https://www.plannedparenthood.org/blog/what-should-i-do-if-i-get-an-sti. Published August 28, 2023. Accessed December 12, 2023.

Jordan Stachel, M.S., RDN, CPT works with a wide variety of individuals, ranging in age from children to the elderly, with an assortment of concerns and clinical conditions. She helps individuals optimize overall health and/or manage disease states using personalized medical nutrition therapy techniques.

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