RPR Testing

On This Page: When to Test | How Test is Performed | Risks | Test Results | Where to Test

What is an RPR Test?

A rapid plasma reagin (RPR) test is a simple blood test used to screen for syphilis infection. Syphilis is caused by the bacterium Treponema pallidum, which is mostly spread through sexual contact. The RPR detects antibodies that your body produces while fighting off a syphilis infection. Alongside specific antibody testing, the RPR test helps confirm an active syphilis infection so that you can be aware if you have it and get treatment to easily cure it.¹

Reasons to Get Tested

The RPR is mainly used as a screening test for syphilis. You may need this test if you show syphilis symptoms, such as a skin rash or sores.

There are also several other reasons you may take an RPR test, including:²

• If you are at risk of being exposed to syphilis:
  • Have another STD or HIV infection
  • Have a sexual partner or partners  diagnosed with syphilis
  • Are a man who has sex with men (MSM)
  • Have engaged in high-risk sexual activity
• Are pregnant, to make sure there’s no active infection that may affect a fetus
• Have been treated for syphilis, to ensure syphilis has been completely cured

Undetected and untreated, syphilis can cause serious health complications. Over time, the infection may progress to late-stage syphilis, which can damage internal organs and cause numbness, paralysis, blindness, or even death.

You can’t always tell if you have syphilis by how you look or feel. Symptoms can be mild or hidden in hard-to-see places on the body, and syphilis can go through stages when no symptoms are present at all. This is why it’s important for those who are sexually active to check up on their health. Getting tested is the only way to know for sure if you have a syphilis infection.

When to Get Tested

Before taking a syphilis test, it’s recommended that you wait at least 3-6 weeks after a potential exposure to ensure your immune system has developed a detectable amount of antibodies. You should also get re-tested 3 months after getting treated for syphilis to confirm the syphilis infection has been cured.

How the Test Is Done

A blood sample is needed. A small needle is used to draw blood from a vein in your arm. After your blood sample is drawn in a private room by a lab technician, it will be examined for antibodies. This test doesn’t require fasting or any additional prep.

Risks of the RPR

The RPR test is minimally invasive and carries very few risks.

As with any laboratory test with venipuncture (when a needle is used to collect a blood sample from a vein), you may feel a slight stinging sensation or pain as the needle is inserted. Because veins can vary in size, giving a blood sample can be more difficult for some people than others. After the test, some people may experience bleeding, bruising, or soreness, and sometimes light-headedness or dizziness.

What Do RPR Results Mean?

Our syphilis test is the qualitative RPR, which will indicate a negative (nonreactive) result or a positive (reactive) result to detect syphilis infection.

Negative / Nonreactive Result

A negative result means antibodies typically produced during a syphilis infection have not been found. This indicates you don’t have syphilis or have tested too early.

If you have tested soon after being infected, a test may not yet show antibodies. This is known as a false-negative, and it happens because it takes your immune system sometime after infection to produce antibodies. For the most accurate results, it’s best to get tested after the recommended window period after exposure.

Positive / Reactive Result

A positive/reactive result means antibodies have been found, indicating a current syphilis infection.

For a doctor to be able to confirm a syphilis diagnosis, a positive RPR test must be followed by a specific treponemal antibody test. Testing for syphilis is a two-step process because the RPR detects antibodies that aren’t specific to syphilis alone. Instead, the RPR tests for antibodies that react to syphilis and appear when cells have been harmed by the bacteria.

This means that certain conditions or infectious diseases may cause a false-positive result, including:³

• IV drug use
• Lyme disease
• Pregnancy
• Tuberculosis (TB)

To rule out the chance of a false positive, if the initial RPR test result is positive, a second test is run for confirmation. Through STDcheck.com, when there is a positive RPR result, the lab will perform a quantitative RPR (titer) test to measure the amount of antibodies present. If necessary, we may also include a Treponema Pallidum Antibodies (TPA) confirmatory test.

What Should You Do If You Test Positive for Syphilis?

If an RPR and a specific confirmatory test indicate you have syphilis, you should seek treatment. Your sex partner(s) should be tested and treated too. Caught in its early stages, syphilis is easy to cure with prescription antibiotics, usually penicillin.⁴

To eliminate the infection, a healthcare professional injects a shot into your muscles. More shots may be needed depending on how far the syphilis infection has progressed. Although we do not administer injections through our online service, for your convenience, you can download and/or print results from your account so you can take them to a doctor or clinic for appropriate support, treatment, and follow-up.

According to the Centers for Disease Control and Prevention (CDC), all people who have primary, secondary, latent, or tertiary syphilis should also be tested for HIV.⁵ This is because many people have both infections (a coinfection), since having syphilis makes it easier to contract and transmit HIV.

Where Can I Get Tested for Syphilis?

You can get tested for syphilis quickly at a doctor’s office, health clinic, or a lab near you. Testing with STDcheck.com only takes a few minutes, and the results come back in 1-2 business days. If you believe you need an RPR test performed to check for syphilis, it’s as easy as ordering a test and then going to your local lab, no appointment is required.

Medically Reviewed by Colleen Ryan, MD on February 14, 2022