Herpes Simplex Virus 1 Immunoglobulin M Antibody (Serum)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like sores, fever, or fatigue that could suggest HSV-1 infection, especially if you’ve had recent contact with someone who has herpes. It may also be used to confirm a diagnosis when other tests are inconclusive or to monitor suspected outbreaks in people with known HSV-1 infection.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re nervous, let your provider know so they can offer comfort measures.

What the Test Results Mean

A positive result means your body has detected IgM antibodies to HSV-1, suggesting recent infection. A negative result means these antibodies were not found in your blood at the time of testing. Results alone don’t confirm the cause of symptoms—your provider will consider them alongside your medical history and other findings.

What to Do If You Get a Positive Result

If your test is positive, your healthcare provider will discuss next steps, which may include confirming the diagnosis with additional tests, treating symptoms, or managing the infection if needed. They may also recommend follow-up testing if symptoms persist or recur.