It depends on the type of blood test you're having and what medicine you take.
If you're not sure or you have any questions about your blood test, ask your healthcare professional for advice.
Never stop taking prescribed medicine unless you are told to do so by your healthcare team.
Medicine and blood test results
Some medicines can affect the results of a blood test, but this does not necessarily mean that you need to stop taking your medicine.
However, a doctor can take this into account when interpreting your test results, so you will not need to stop taking your medicine.
If you're unsure, keep taking your medicine as prescribed and check with your doctor.
You may also want to take your medicine with you to show the person doing your blood test.
Herbal remedies, vitamins or supplements can also affect results, so tell your doctor if you take any of these.
When to stop taking a medicine
You should never stop taking prescribed medicine, unless you're told to do so by your doctor.
Sometimes, you may need to stop taking a medicine before a blood test.
Testing your medicine
If you're having a blood test to check whether your medicine is working, in most cases you should keep taking your medicine.
For example, if you're taking medicine to lower your cholesterol level, you should keep taking it before your cholesterol blood test, as the result will show whether the medicine is working.
Page last reviewed: 3 January 2020
Next review due: 3 January 2023