Table of ContentsView AllTable of ContentsPurposeResultsNew or Recurrent InfectionFalse Positive ResultsRetestingFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Purpose
Results
New or Recurrent Infection
False Positive Results
Retesting
Frequently Asked Questions
A herpes IgM (immunoglobulinM) test is a blood test that can detect earlyherpes simplex virus (HSV) infection. HSV is a contagious condition that causessores around the mouthor genitals.
Andrew Brookes / Getty Images
This article explains the purpose of the herpes IgM test. It also discusses what the results mean, as well as retesting considerations.
What Does Herpes Look Like?
What Is the Purpose of a Herpes IgM Test?
The herpes IgM test is a simple blood test and results are usually available within a week.
Keep in mind that:
If you believe you have been exposed but have no symptoms, you should waitat leasttwo weeks before getting tested. You may want to wait even longer depending on which tests are available in your area.
CDC Does Not Recommend HSV IgM TestingThe Centers for Disease Control and Prevention (CDC) does notrecommend HSV IgM testing because it cannot differentiate betweenherpes simplex virus type 1(the type commonly associated with oral herpes) andherpes simplex virus type 2(the type more commonly linked to genital herpes). The test might also deliver a positive result during a recurrent oral or genital herpes episode.
CDC Does Not Recommend HSV IgM Testing
The Centers for Disease Control and Prevention (CDC) does notrecommend HSV IgM testing because it cannot differentiate betweenherpes simplex virus type 1(the type commonly associated with oral herpes) andherpes simplex virus type 2(the type more commonly linked to genital herpes). The test might also deliver a positive result during a recurrent oral or genital herpes episode.
The Two Types of Herpes Simplex
How Are the Results Interpreted?
Results of a herpes IgM test are usually reported as positive, negative, or equivocal.
Herpes IgM test results:
How Accurate Are Your Medical Test Results?
Is It a New or Recurrent Infection?
Herpes IgM levels tend to go up early in an infection, and levels often go down with time. This means a positive herpes IgM result is most often associated with a new infection. However, individuals with recurrent herpes infections may also have positive herpes IgM blood results.
Individuals may not have a positiveimmunoglobulin G (IgG) test, an antibody test that detects IgG, until they’ve been infected for at least several months. However, IgG levels tend to remain high throughout the course of an infection, while IgM levels are more variable.
This means that if an individual has positive results on both IgG and IgM tests, they may be having a recurrent herpes episode, instead of a new infection. A positive IgM test alone is more likely to be a new infection.
Prevention of Herpes
Is It Possible to Get a False Positive Result?
Afalse positiveis when a test says you have a condition that you actually don’t have. This can happen with the herpes IgM blood test.
In some cases you may not be infected at all. However, you may have a different virus that triggers a positive on this blood test. This may include theEpstein-Barr virus, which is in the herpes virus family, orparvovirus, a contagious virus that can lead toflu-like symptoms.
If you don’t have symptoms, you may want to go back for IgG testing at a later date. If you do have symptoms, your healthcare provider can test the sores for herpes directly with a swab test.
A positive result is more likely to be accurate if you have or have had symptoms of a herpes outbreak.
Should I Get Tested Again?
You may want to go for a repeat test after six months if you do not undergo regularsexually transmitted infection (STI) screening. In doing so, you’re more likely to identify an infection without missing the window in which the tests are accurate.
Speak with your healthcare provider about when it’s best for you to get tested, and if there are other tests you should consider.
Summary
A positive IgM test might mean you have a new or recurrent HSV infection. If you have a positive IgM test and a negative IgG test, you likely have a new infection.
To verify your test result, consider following up with your healthcare provider in six months for repeat testing.
Frequently Asked QuestionsHSV IgG and HSV IgM are antibodies produced to fight the herpes simplex virus. Blood tests can look for these antibodies to diagnose herpes.A positive HSV IgM blood test indicates that herpes immunoglobulin M is present. This means the person is carrying the herpes virus. A false positive is possible.A positive HSV IgG blood test indicates that herpes immunoglobulin G is present. This means the person is carrying the herpes virus. An HSV IgG test will not be positive in the early stages of an infection.It may. However, if HSV IgM and HSV IgG are both positive, it indicates that the herpes virus has been present for at least several months.
HSV IgG and HSV IgM are antibodies produced to fight the herpes simplex virus. Blood tests can look for these antibodies to diagnose herpes.
A positive HSV IgM blood test indicates that herpes immunoglobulin M is present. This means the person is carrying the herpes virus. A false positive is possible.
A positive HSV IgG blood test indicates that herpes immunoglobulin G is present. This means the person is carrying the herpes virus. An HSV IgG test will not be positive in the early stages of an infection.
It may. However, if HSV IgM and HSV IgG are both positive, it indicates that the herpes virus has been present for at least several months.
1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Centers for Disease Control and Prevention.Genital herpes.
Amudha VP, Rashetha, Sucilathangam G, Cinthujah B, Revathy C.Serological profile of HSV-2 in STD patients: Evaluation of diagnostic utility of HSV-2 IgM and IgG detection.J Clin Diagn Res. 2014;8(12):DC16-9. doi:10.7860/JCDR/2014/10586.5314
Liermann K, Schäfler A, Henke A, Sauerbrei A.Evaluation of commercial herpes simplex virus IgG and IgM enzyme immunoassays.J Virol Methods. 2014;199:29-34. doi:10.1016/j.jviromet.2014.01.001
Morrow R, Friedrich D.Performance of a novel test for IgM and IgG antibodies in subjects with culture-documented genital herpes simplex virus-1 or -2 infection.Clin Microbiol Infect. 2006;12(5):463-9.
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
