Home HIV tests: how self-tests work and how accurate they are

Why people use them

A self-test lets you check for HIV at home or somewhere private, at a time that suits you. You don’t need an appointment, and nobody else needs to know. For a lot of people that makes testing much easier to actually do.

The trade-off is timing. Home tests take longer than lab tests to pick up a new infection, so they’re best for checking an exposure that happened a while ago, or for regular testing.

The two main types

Oral swab tests. You swab your gums to collect fluid from your mouth, then test that sample as the kit describes. This is the type CDC describes for the US.

Finger-prick tests. You prick your finger and put a drop of blood into the test. The NHS describes home tests that use either saliva or blood from your finger.

Both kinds give a result in minutes; CDC says within 20 minutes. Most home tests of either kind are antibody tests: they look for the antibodies your body makes in response to HIV, not for the virus itself.

How accurate are they?

The biggest factor is when you test. Antibodies take time to appear, so antibody tests have a long window period: CDC says they can usually detect HIV 23 to 90 days after an exposure.

• Before day 23: too early. A negative result doesn’t tell you anything about a recent exposure.
• Between day 23 and day 90: a negative result is reassuring, but not final.
• From day 90: a negative result is conclusive, as long as you haven’t had another exposure since.

Here is how much a negative home test can lower an estimate. For one act of receptive anal sex with a partner who has HIV and isn’t on treatment, the estimate starts at 1.4% (about 1 in 72). A negative antibody test at four weeks lowers it to 0.85% (about 1 in 120). At day 90, it falls to 0.0014% (about 1 in 71,000). A lab antigen/antibody test at four weeks would already give 0.18% (about 1 in 540). For more on timing, see HIV test accuracy by week.

The other factor is using the test properly. CDC warns that if you don’t follow the directions, the test may not work. Read the instructions before you start, and use the helpline number in the kit if you’re unsure.

Choosing and buying a test

• In the US, you can buy self-tests at pharmacies and online. CDC says you can order free self-tests through Together TakeMeHome, and gettested.cdc.gov shows local organizations offering free or reduced-cost self-tests.
• In the UK, the NHS advises buying from a reliable source. The kit should be clearly marked for self-testing, carry a CE mark and show the manufacturer’s details.
• Elsewhere, sexual health clinics and national health services can tell you which self-tests are approved where you live.

What your result means

Negative. If you tested at least 90 days after your last possible exposure, you don’t have HIV from that exposure. If you tested sooner, test again after day 90, or get a lab test, which is conclusive from day 45.

Positive (reactive). This means you could have HIV. It is not a diagnosis yet. You need a follow-up test at a clinic or with a health care provider to confirm it. See what to do after a positive test.

Invalid. The test didn’t work. Use another self-test, or get tested at a clinic or testing center.

When a home test isn’t the right choice

• The exposure was in the last 72 hours. No test can detect HIV this early. What matters now is PEP (post-exposure prophylaxis).
• You want an answer sooner than 90 days. A lab antigen/antibody test at a clinic is conclusive from day 45, and a NAT (nucleic acid test) from day 33.
• You have symptoms after a recent exposure. See a clinician and ask for a test that can detect early infection.

What to do now

1. Count the days since the exposure.
2. Under 72 hours? Ask about PEP first.
3. Under 90 days? A home test can reassure you, but plan a retest at day 90, or use a lab test.
4. Follow the kit’s instructions exactly, and read the result in the time it gives.
5. Any positive result needs a confirmatory test at a clinic.