What Is a Herpes Simplex Virus Antibodies Test (IgG and IgM HSV)?

Medically Reviewed by Jabeen Begum, MD on October 09, 2023
4 min read

The herpes simplex virus (HSV) antibodies test is a type of herpes simplex test that determines whether or not you’ve ever been exposed to this virus. Specifically, it’s a blood test that looks for certain antibodies in your body.  

Antibodies are proteins that are made by your immune system to fight off particular pathogens — usually bacteria and viruses. This test looks to see if you have antibodies against either HSV-1 or HSV-2 — the two kinds of herpes viruses.  

Your body begins to make two relevant types of HSV-1 antibody or HSV-2 antibody around 18 to 21 days after you’re first infected. These two types of antibodies are called IgG and IgM antibodies. 

IgG antibodies are the most common kind and IgM antibodies are the first kind that your body makes when you first come into contact with a virus or bacteria. Both can be found in your blood and other bodily fluids. 

The best versions of this test can tell the difference between previous exposure to either HSV-1 or HSV-2. 

The herpes simplex virus is a type of virus that causes infections in humans. Approximately 3.7 billion people under the age of fifty — or 67% — have been infected with HSV-1 in their lifetimes. There are about 491 million cases of HSV-2 worldwide — or 13% of the global population between the ages of 15 and 49. 

HSV is spread through direct contact with the virus. This can happen during sex or while giving birth. 

The virus leads to an increased risk of infection with human immunodeficiency virus (HIV). It can also cause you to develop more severe conditions if you have a compromised immune system. 

HSV can have particularly problematic results if you’re infected with the virus when you’re born. The chance of passing it on while pregnant is low but — if it happens — it can lead to disabilities and death. 

There’s also a social stigma associated with this virus that can be damaging to your mental health if you ever become infected. 

In most cases of infection with the herpes simplex virus, you won’t have any symptoms at all or they’ll be very mild. Typically, your first outbreak is the most severe. Symptoms will periodically come back, but studies show that these bouts are shorter and less symptomatic than the first.

Breakouts typically happen in the genital region when you have HSV-2 and near your lips when you have HSV-1. But you can also get HSV-1 infections in your genital region. 

Symptoms include: 

  • Blisters that appear either individually or in clusters; they can be quite painful and may ooze. 
  • Soreness, pain, and burning at the infection site
  • Headaches
  • Fever
  • Body aches and pains

Herpes antibodies tests are not recommended when your doctor wants to diagnose an active infection. The best tests, in this case, are to collect a sample from you and attempt to culture the virus or test for the presence of its genome using a technique called polymerase chain reaction (PCR). 

Should an active infection be detected with a PCR test, your doctor may prescribe  antiviral medications to help prevent outbreaks or shorten their severity. When outbreaks occur when you are on these medications, they’re typically shorter and create fewer lesions than when you aren’t taking them. 

Common antiviral medications include acyclovir, famciclovir, and valacyclovir. 

Your doctor may recommend an antibody test in addition to these other tests for an active infection. But it is more likely that they will recommend this test for another reason, including if: 

  • You have recurring symptoms but active test results are negative.
  • You believe you were recently exposed but don’t yet have symptoms.
  • You’re pregnant or trying to become pregnant.
  • You have HIV or have a high risk of encountering HIV. 

A herpes antibodies test works by looking in your blood for HSV-1 antibodies or HSV-2 antibodies — typically the IgG type but sometimes the IgM type.

These tests only indicate exposure to either HSV-1 or HSV-2 at some point in your past. This does not necessarily mean that HSV is causing any current symptoms that you may have — since the exposure could have been years ago. 

If you are worried about a new infection, it might be useful to take the test again around 21 days later to make sure that your body has had enough time to produce the antibodies. 

The tests can give false-positive results. You may want to repeat the test or try other forms of testing to confirm the results.    

The Centers for Disease Control and Prevention, the Infectious Diseases Society of America, and the American Society for Microbiology all recommend the use of the IgG antibodies test over the IgM HSV test. 

IgG tests are preferred because: 

  • For herpes, IgG and IgM antibodies show up around the same time — normally, IgM antibodies appear first. 
  • IgM antibodies may only last a few months and may not be made after the first outbreak — but IgG antibodies last indefinitely and are made during all outbreaks. 
  • IgG antibodies can distinguish between HSV-1 and HSV-2 and IgM antibodies can’t.