Understanding the Herpes Simplex Virus Type 1 and Type 2 IgM blood test

The Herpes Simplex Virus Type 1 and Type 2 IgM test is a blood test that detects IgM antibodies produced by the immune system shortly after infection with Herpes Simplex Virus Type 1 or Herpes Simplex Virus Type 2. IgM antibodies are typically the first antibodies generated following exposure, making this test useful for identifying recent or early-stage infection.

Herpes Simplex Virus Type 1 is most commonly associated with oral infections such as cold sores, while Herpes Simplex Virus Type 2 is more frequently linked to genital infections. However, both virus types can infect either area of the body, which is why combined testing for both types is clinically relevant.

This test is especially valuable when physical symptoms are present but lesions are not suitable for swab testing, have already healed, or when symptoms are atypical. Unlike IgG testing, which indicates past exposure, IgM testing focuses on current or recent immune activity, offering insight into recent infection or early viral reactivation.

When testing for Herpes Simplex Virus Type 1 and Type 2 IgM is appropriate

You may consider this test if you suspect recent exposure, have developed new symptoms, or want medical clarity following intimate contact. Early identification supports informed healthcare decisions, helps reduce transmission risk, and provides reassurance when symptoms are unclear.

Herpes Simplex Virus infections are often misunderstood. Many individuals do not experience classic blisters or sores, and symptoms may be mild, short-lived, or mistaken for other conditions such as fungal infections, urinary tract infections, or skin irritation. Blood testing is therefore an important diagnostic option when symptoms are vague or when no visible lesions are present.

Testing may be particularly appropriate if you experience:

• New oral or genital sores, blisters, or ulcers
• Tingling, itching, or burning sensations around the lips or genital area
• Flu-like symptoms during a suspected first episode
• Pain or discomfort during urination without an obvious cause
• Recent unprotected sexual contact
• A partner diagnosed with Herpes Simplex Virus
• Healed lesions that can no longer be swabbed
• Ongoing anxiety following possible exposure

Key clinical advantages of this blood test

• Detection of early immune response
  Identifies antibody activity shortly after infection.
• Effective when lesion swabbing is not possible
  Useful once sores have healed or were never present.
• Supports early clinical decision-making
  Enables timely advice and follow-up planning.
• Clarifies uncertain or atypical symptoms
  Helpful when symptoms mimic other conditions.
• Assists with responsible sexual health management
  Provides information for informed discussions with partners.
• Distinguishes recent infection from past exposure
  Focuses on current immune activity rather than historical exposure.
• Simple, minimally invasive testing process
  No fasting or preparation required.
• Provides reassurance through objective results
  Reduces uncertainty after potential exposure.

How testing is carried out

We offer two convenient testing options across the UK:

Clinic-based blood testing

• Choose your nearest UK clinic
• A healthcare professional collects your blood sample
• The sample is analysed in a certified laboratory
• Results are issued once testing is complete

Home or hotel blood collection (+£60)

• A qualified phlebotomist visits your home, workplace, or hotel
• Blood is collected at a time convenient for you
• No travel required
• Available nationwide across the UK

Both options provide the same laboratory accuracy and clinical reliability.

Interpreting your Herpes Simplex Virus Type 1 and Type 2 IgM results

Low IgM levels

Low or undetectable IgM levels suggest no recent immune response to Herpes Simplex Virus Type 1 or Type 2. This may indicate no recent infection or testing performed before antibodies have developed.

Typical UK reference range:

• Negative: < 0.9 index

Borderline IgM levels

Borderline results indicate antibody levels that are not clearly negative or positive. This may occur very early in infection or during immune fluctuation.

Typical UK reference range:

• Equivocal: 0.9 – 1.1 index

Elevated IgM levels

Elevated IgM levels indicate a recent or active immune response, most commonly associated with a primary infection or early viral reactivation.

Typical UK reference range:

• Positive: > 1.1 index