A herpes simplex virus (HSV) infection can cause small, painful sores that look like blisters on the skin or the tissue lining (mucous membranes) of the throat, nose, mouth, urethra, rectum, and vagina. In rare cases, HSV can infect other parts of the body, such as the eyes and the brain.
HSV tests are most often done for sores on the genitals. If blisters or sores are present, a sample from a sore can be tested to check if it is caused by the herpes virus. HSV testing may also be done using other types of samples, such as spinal fluid, blood, urine, or tears.
Blood testing can be done to find out if you have been exposed to the herpes virus. But it is not usually done as part of a regular screening for sexually transmitted infections (STIs). That's because a positive result only means you have been exposed to the virus. The test can't tell if you will get sores or where on the body they might show up. The test also can't tell you if any sores you have are caused by the herpes virus.
There are two types of herpes, HSV-1 and HSV-2. Some HSV tests can tell which type of herpes you have. Knowing the type of HSV can help you decide if you want treatment or what treatment might be best for you and your partner(s).
Why It Is Done
A test for herpes may be done to:
- Find out whether HSV is causing sores around the mouth or on the genitals.
- Find out which virus type (HSV-1 or HSV-2) is causing sores around the mouth or on the genitals.
- Find out whether the sex partner of a person with genital herpes may be infected with HSV.
- Diagnose a herpes infection in an infant born to a person who has genital herpes.
How To Prepare
If you may have genital herpes, do not have sexual contact until your test results are back. There are treatments that can help lower the chance of spreading it to others.
How It Is Done
For a viral culture or PCR test, a clean cotton swab is rubbed against a herpes sore to collect fluid and cells to examine. Samples may be collected from the vagina, cervix, penis, urethra, eye, throat, or skin. Doctors usually collect a sample from small sores that are only a few days old. Viruses are more likely to be found in small, newly formed sores.
A health professional uses a needle to take a blood sample, usually from an arm.
Rapid tests are available at some clinics. These tests check blood from a finger stick for antibodies to HSV-2. The results are generally ready in about 10 minutes. These tests may not be available everywhere.
How It Feels
You are likely to feel some mild discomfort or pain when the sores are rubbed to collect a sample for testing.
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Test results are ready at different times for the different tests. Some test results may be back the same day. Others may take a few days.
Normal results are called negative.
No herpes simplex virus (HSV) or antibodies are found.
Abnormal results that show HSV are called positive.
Herpes virus or antibodies are found.
A normal (negative) test result does not mean you do not have a herpes infection. If the first test is negative but you have symptoms of herpes, more tests may be done.