Can you reuse pregnancy tests?
Charlotte Thomas
Social EditorFind out if it’s safe to reuse a pregnancy test, if the results from a reused pregnancy test are reliable, and how to get the best results from your test.
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Pregnancy tests can be expensive. And if you’re trying to conceive and getting through a number of tests, or you get an inconclusive result, it can be tempting to reuse one.
However, it’s not advised to reuse pregnancy tests. This is because the results are unreliable if used more than once.
You should only use pregnancy tests once and follow the instructions on the packaging carefully to get an accurate reading.
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Why can’t you reuse pregnancy tests?
Pregnancy tests work by detecting the pregnancy hormone human chorionic gonadotropin (hCG) in your urine. The hormone hCG reacts with antibodies in the strip to produce a chemical reaction.
Depending on your particular test, if hCG is detected, lines or words will appear to let you know you're pregnant.
However, this chemical reaction can only happen once.
Any result taken from a test that has been reused is unreliable. To test again, you’ll need to use another pregnancy test.
This applies to both standard and digital pregnancy tests as they both work in the same way.
Can anything else affect the accuracy of a pregnancy test?
As well as reusing a pregnancy test, other things can affect its accuracy. These include:
- The expiry date – pregnancy tests have expiry dates so check your isn’t out of date or the chemical reaction might not work properly
- When you look at the results – always look at the results of your test as close to the time stated on the box as possible. If you leave it too long, the result can be inaccurate.
- If it gets wet – if you splash your test with water it can cause a chemical reaction and affect the accuracy of the test
- If it’s too early in your pregnancy – hCG is usually produced around six days after fertilisation and it can take a couple more days until it can be detected by a test. In the very early stages of pregnancy, you may get a false negative result. If you think you could be pregnant, it’s best to wait a few days and try again
- Medication – the NHS says that some medicines can affect the results of pregnancy tests
What is the best way to do a pregnancy test?
You should always follow the specific instructions on your pregnancy test but as a rough guide:
When to take a pregnancy test
The NHS says most pregnancy tests can be carried out from the first day of a missed period. If you’re not sure when your next period is due, wait at least 21 days from when you last had unprotected sex.
You can also get very sensitive pregnancy tests, known as early detection pregnancy tests. These can be used four to five days before your period is due and some can even detect a pregnancy as early as eight days after conception.
Find out more about when you can take a pregnancy test here.
How to do a pregnancy test
Most pregnancy tests require you to pee on a stick. It doesn’t usually matter what time of day you do this but make sure you follow the instructions as different tests can be slightly different.
Check the results when it tells you to on the instructions – this is usually after a few minutes. Don’t leave it too long as the results can be affected.
Can pregnancy tests give wrong results?
Most home pregnancy tests are very accurate, as long as you follow the instructions and use them before the expiry date.
A positive result is usually accurate, however you may get a false negative on some occasions, especially in the very early days of a pregnancy.
If you've had a number of negative tests but your period still hasn't arrived, talk to your GP.
Use a fertility monitor so you can track the best days to try and get pregnant. We like Clearblue's Advanced Fertility Monitor – see more details here at Amazon.
Can I get free pregnancy tests?
As well as buying tests from pharmacies and most supermarkets, if you’re worried about the cost, you can get free pregnancy tests from:
- Community contraceptive clinics – find your nearest here
- Your GP may offer free pregnancy tests
- Sexual Health clinics – find your nearest here
- Brooks centres if you’re under 25
- Some young people's services – call the national sexual health helpline on 0300 123 7123 for details
Discuss pregnancy tests and early signs of pregnancy with others in our forum.
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