How It Works

How It Works

Herpes home tests look for antibodies your immune system makes in response to the herpes simplex virus. This page explains how that works, how to take the test, and what a result can and cannot tell you.

Screening, not diagnosis

A home test is a first step that can prompt a conversation with a clinician. It does not diagnose herpes on its own, and any reactive result should be confirmed with laboratory testing.

The basicsThe science of antibody screening

After the body encounters a virus, the immune system produces antibodies — proteins that recognise that specific virus. These tests use a method called lateral flow: a small sample travels along a test strip, and if the relevant antibodies are present at a detectable level, they bind to reagents on the strip and produce a visible line. A separate control line appears whenever the test has run correctly, regardless of your result.

Using the kitStep by step

This is a general summary. The instructions supplied with your specific kit always take priority if anything differs.

1

Prepare

Wash and dry your hands, and lay the kit components on a clean, flat surface.

2

Take the sample

Clean a fingertip, use the lancet as instructed, and collect blood with the pipette to the marked level.

3

Apply to the cassette

Add your sample to the sample well, then add the stated number of buffer drops. Drop count per IFU

4

Wait

Start a timer for the wait time in your instructions. Timing per IFU

5

Read

Read the window within the stated period and compare it against the result key below.

Timing mattersThe window period

Antibodies take time to develop after exposure. If you test too soon, the test may not detect a recent infection, giving a non-reactive result even when the virus is present. This gap is called the window period. Testing is most reliable after the interval stated in your kit's instructions. Recommended window per IFU

InterpretingReading your result

Every kit shows a control line (C) that confirms the test ran, and a test line (T) that indicates a reactive result.

Non-reactive

Control line only. No antibodies detected.

Reactive

Control and test lines. Antibodies may be present.

Invalid

No control line. Repeat with a new kit.

ContextWhat a result does and doesn't mean

A reactive result means
  • Antibodies may have been detected, suggesting past exposure to the virus.
  • You should confirm the result with a healthcare professional and laboratory testing.
A result does not tell you
  • When or where an infection was acquired, or where on the body it is.
  • Whether you are currently able to pass the virus on.
  • A definitive diagnosis — only a clinician and laboratory testing can provide that.

Next stepsWhen to speak to a clinician

Contact your GP or a sexual health service if you have a reactive result, if you have symptoms, if you have had a recent known exposure, or if you are unsure how to interpret your result. In the UK you can also call NHS 111 for non-emergency advice.