Syphilis (IgG/IgM)

What is the Syphilis (IgG/IgM) Test?

The Syphilis IgG/IgM test is a blood test that detects antibodies produced in response to infection with Treponema pallidum, the bacterium that causes syphilis. IgM antibodies are typically associated with recent or active infection, while IgG antibodies indicate longer-term or past exposure.

Unlike PCR testing, which detects the organism directly from a lesion, antibody testing reflects the immune response and is useful across different stages of syphilis. This makes it suitable for screening, follow-up, and assessment when no visible lesions are present.

The test is commonly used as part of sexual health screening and for investigating unexplained symptoms or potential exposure.

Why do I need a Syphilis (IgG/IgM) test?

Syphilis is often called the “great imitator” because its symptoms can resemble many other conditions or be entirely absent. Blood testing is essential for identifying infection when physical signs are unclear or have resolved.

You may need this test if you:

• Have had unprotected sexual contact
• Are undergoing routine sexual health screening
• Have symptoms such as rash, ulcers, or unexplained neurological signs
• Have a partner diagnosed with syphilis
• Need follow-up testing after previous infection
• Are pregnant or planning pregnancy
• Have unexplained positive or borderline syphilis screening results

Early identification helps prevent progression to later stages, which can affect the nervous system, heart, and other organs.

Benefits of the test

1. Detects current and past infection
   Measures both IgM and IgG antibodies for broader assessment.
2. Suitable when no lesions are present
   Useful when PCR swabbing is not possible.
3. Supports early and late-stage detection
   Antibodies remain detectable across disease stages.
4. Essential for routine screening
   Commonly included in sexual health and antenatal panels.
5. Helps clarify exposure history
   Distinguishes recent versus past immune response patterns.
6. Supports monitoring after diagnosis
   Useful for follow-up alongside other syphilis tests.
7. Simple blood-based testing
   Requires only a blood sample.
8. Reduces missed diagnoses
   Identifies infection even when symptoms are absent.

Step-by-step: How we offer testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician draws a blood sample
• Sample is sent to the laboratory
• Results are issued once analysis is complete

Home or hotel visit (+£60, UK-wide)

• Book a mobile phlebotomist
• Blood sample taken at your home or hotel
• No need to attend a clinic
• Sample securely transported to the laboratory

Your results explained

Negative (no antibodies detected)

• No IgG or IgM antibodies identified
• UK standard: Negative
• Suggests no evidence of current or past infection

IgM positive (recent or active infection)

• IgM antibodies detected, with or without IgG
• UK standard: IgM reactive
• Suggests recent or active syphilis infection

IgG positive (past or treated infection)

• IgG antibodies detected, IgM negative
• UK standard: IgG reactive
• Indicates previous exposure or treated infection