HSV-1 IgG Type Specific Test: What Positive, Negative & Equivocal Results Mean

Other names: HSV 1 IgG, Type Spec

check icon Optimal Result: 0 - 0.91 index.

Reviewed by HealthMatters Clinical Review Team 

Last updated: February 2026

Key Takeaways

  • A positive result means past HSV-1 exposure — it does not mean you have an active infection
  • HSV-1 is extremely common: roughly 67% of adults under 50 have it, most without symptoms
  • IgG antibodies persist for life — a positive result will not revert to negative
  • This test cannot tell you when you were infected or whether the virus is currently active
  • The index value magnitude does not indicate severity — positive is positive regardless of number

Optimal Results

Negative: 0.00–0.90 index
Equivocal: 0.91–1.09 index (lab dependent)
Positive: ≥1.10 index

Your lab lists a reference range of 0–0.91 index for a negative result.

Values above the negative range indicate detectable antibodies to HSV-1.

HSV-1 IgG Type Specific Test: What Positive, Negative & Equivocal Results Mean

The HSV-1 IgG type specific test detects whether your immune system has ever encountered herpes simplex virus type 1. A positive result — any index value above 1.09 — means you were infected at some point, typically years or even decades ago. It does not mean you are contagious right now, that you will develop symptoms, or that you need treatment. Most people with positive HSV-1 IgG results live entirely normal lives with no intervention.


What does the HSV-1 IgG type specific test measure?

The HSV-1 IgG type-specific test measures IgG antibodies to herpes simplex virus type 1 (HSV-1) in the blood.

IgG antibodies indicate past exposure or established infection, not a new infection.

This is a type-specific herpes test that distinguishes HSV-1 from HSV-2.

HSV-1 is extremely common. A large percentage of adults worldwide will test positive even without symptoms.


Why would a doctor order an HSV-1 IgG test?

Doctors may order an HSV-1 IgG test to:

  • Confirm prior HSV-1 exposure

  • Evaluate cold sores or oral lesions

  • Clarify genital herpes source

  • Screen during fertility or pregnancy planning

  • Assess partner transmission risk

  • Investigate unexplained oral or genital symptoms

This test does not diagnose a brand-new infection. PCR or swab testing is used for active outbreaks.


How do you interpret HSV-1 IgG results?

Negative (0–0.91 index)

A result within the lab’s reference range (0–0.91) means no HSV-1 IgG antibodies were detected.

Possible meanings:

  • No prior exposure

  • Testing occurred too soon after exposure

  • Rare false negative

Antibodies can take 2–12 weeks to appear.
If recent exposure is suspected, repeat testing may be recommended.


Positive (above reference range)

A value above the reference range indicates HSV-1 IgG antibodies were detected.

This means:

  • You were infected with HSV-1 at some point

  • The infection is not new

  • The virus may be dormant

It does not indicate:

  • When infection occurred

  • Whether infection is oral or genital

  • Whether symptoms will occur

Most people with positive HSV-1 IgG have mild or no symptoms.


Equivocal or borderline

The equivocal zone is typically 0.91–1.09 index (though this varies by lab). Results in this range are inconclusive. The CDC and most infectious disease specialists recommend repeating the test in 3–4 weeks if equivocal. A single equivocal result should never be used to confirm or exclude HSV-1 infection.

This may indicate:

  • Very early infection

  • Low antibody levels

  • Lab variability

Repeat testing in several weeks is often recommended.


Can an HSV-1 IgG result be a false positive?

Yes — though less commonly than with HSV-2 tests. Research published in 2024 found that common commercial assays for HSV-1 IgG have high specificity (above 97%) but lower sensitivity, meaning false positives are uncommon but false negatives occur more often. Index values just above the cutoff (1.10–3.0) carry a slightly higher risk of being false positives. If you received a weakly positive result and have no symptoms or known exposures, discuss confirmatory testing — such as the HSV western blot — with your doctor.

What is HSV-1 and how common is it?

HSV-1 is a herpesvirus most commonly associated with:

  • Cold sores

  • Fever blisters

  • Oral herpes

It can also cause genital herpes through oral-genital contact.

After infection, HSV-1 remains in the body in a dormant state and may reactivate periodically.

Many carriers never develop symptoms.

According to the World Health Organization, approximately 3.7 billion people under age 50 — or 67% of the global population — have HSV-1 infection. In the United States, the CDC estimates roughly half of all adults have HSV-1, the majority acquiring it in childhood through non-sexual contact.


Symptoms associated with HSV-1

Oral symptoms:

  • Lip blisters

  • Tingling or burning

  • Painful mouth sores

  • Fever during first infection

Genital symptoms:

  • Genital lesions

  • Painful urination

  • Flu-like symptoms

  • equivocalRecurrent sores

Initial infections are usually more noticeable than later recurrences.


HSV-1 transmission

HSV-1 spreads through direct contact with infected saliva or skin.

Transmission can occur through:

  • Kissing

  • Oral-genital contact

  • Skin-to-skin contact

  • Sharing utensils or lip products

Risk is highest during active outbreaks but can occur without visible sores.


When results matter clinically

HSV-1 IgG testing is most useful when:

  • Evaluating recurrent cold sores

  • Distinguishing HSV-1 vs HSV-2

  • Planning pregnancy

  • Screening before fertility treatment

  • Clarifying partner risk

Because HSV-1 is so common, a positive result alone usually does not require treatment unless symptoms occur.


How is HSV-1 treated and managed?

There is no cure for HSV-1, but it can be managed.

Treatment options:

  • Acyclovir

  • Valacyclovir

  • Famciclovir

  • Suppressive therapy for frequent outbreaks

Outbreak triggers may include:

  • Stress

  • Illness

  • Sun exposure

  • Hormonal changes

  • Fatigue

Many people never require treatment.


What is the difference between HSV-1 and HSV-2?

HSV-1:

  • Often oral

  • Sometimes genital

  • Less frequent recurrences

HSV-2:

  • Usually genital

  • More frequent recurrences

  • Higher transmission risk

Type-specific IgG testing distinguishes between them.


When should you talk to a doctor about your HSV-1 result?

Discuss your result if you:

  • Have frequent cold sores

  • Have genital symptoms

  • Are pregnant

  • Are immunocompromised

  • Recently had a new exposure

  • Have a partner with herpes

A positive HSV-1 IgG without symptoms is usually not concerning.


Frequently searched questions

What does HSV-1 IgG index mean?

It measures antibody levels. Values above the reference range indicate prior exposure.

Is 0.91 positive?

No. Up to 0.91 is within the negative reference range on this lab.

Can HSV-1 IgG go away?

No. Once HSV-1 IgG antibodies develop, they remain detectable for life. This is true even during periods when the virus is dormant and you have no symptoms. The antibody level may fluctuate slightly over time but will not drop below the positive threshold. A future negative result would most likely indicate a lab error or a different test being used.

Can I have HSV-1 without symptoms?

Yes. Many people never develop symptoms.

What does it mean if your HSV-1 IgG Type Specific Test: What Positive, Negative & Equivocal Results Mean result is too high?

Elevated HSV-1 IgG (Type-Specific) — Interpretation

Understanding IgG vs IgM together

When HSV antibody tests include both IgG and IgM, the results can be confusing.

  • IgG antibodies take longer to appear after infection (usually several weeks), but once present they typically remain detectable for life.

  • IgM antibodies may appear earlier after exposure but often fade within weeks. However, IgM can also reappear during recurrent outbreaks and is not a reliable indicator of a new infection.

Because of this, IgM results alone should be interpreted cautiously.

General patterns:

  • Positive IgG, negative IgM: Most consistent with an established or past infection (typically more than several weeks to months old).

  • Positive IgM with or without IgG: May occur in early infection but can also appear during recurrent episodes. It does not reliably confirm a recent infection.

  • Positive IgG and positive IgM: Infection timing cannot be determined from these results alone.

Studies have shown that a significant proportion of people with recurrent herpes infections can test positive for IgM during reactivations, so IgM is not considered a definitive marker of recent infection.


What a positive HSV-1 IgG type-specific result means

Testing positive for HSV-1 IgG (type-specific) indicates prior exposure to herpes simplex virus type 1 and the presence of IgG antibodies to the virus.

HSV-1 is one of two herpes simplex viruses. It most commonly causes oral herpes (cold sores or fever blisters), though it can also cause genital herpes.

Key interpretation points

Past exposure
A positive HSV-1 IgG result means you were infected with HSV-1 at some point in the past. IgG antibodies usually appear several weeks after infection and typically remain detectable long term.

Type-specific testing
A type-specific HSV-1 IgG test distinguishes HSV-1 from HSV-2. This helps clarify which virus you have been exposed to and can help guide counseling about symptoms and transmission risk.

Timing of infection
This test cannot determine exactly when infection occurred. Many people acquire HSV-1 in childhood or early adulthood and may not recall symptoms.

Symptoms may be absent
Many people with HSV-1 never develop noticeable symptoms or have very mild symptoms that go unrecognized.

Typical presentation
If symptoms occur, they most often involve oral herpes such as cold sores or lip blisters. HSV-1 can also cause genital herpes, though HSV-2 is more commonly associated with recurrent genital outbreaks.

Transmission and reactivation
HSV-1 spreads through direct contact with infected skin or saliva. The virus remains dormant in nerve cells and can reactivate periodically, causing recurrent sores in some individuals.

Management
There is no cure for HSV-1, but outbreaks can be managed with antiviral medications such as acyclovir or valacyclovir. Many people never require treatment if symptoms are mild or infrequent.


When to discuss with a clinician

Consider speaking with a healthcare provider if you:

  • Have frequent cold sores or genital symptoms

  • Are pregnant or planning pregnancy

  • Recently had a possible new exposure

  • Are concerned about transmission to a partner

  • Have immune system concerns

A positive HSV-1 IgG result without symptoms is common and usually not medically concerning on its own. Interpretation should always consider symptoms, exposure history, and other test results.

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