What is clopidogrel?
Clopidogrel is a type of blood thinner commonly given to patients after they have had a stroke, or mini stroke (TIA). It stops platelets, the clotting cells of the blood, from sticking together to form clots which can block blood supply.
This means that clots are less likely to form and lowers the risk of a clot blocking a blood vessel within your brain thus lowering the risk of stroke. Usually, clopidogrel is taken as a once daily medication, lifelong.
What is clopidogrel resistance?
When people take clopidogrel, it is changed into its active form by a chemical enzyme found in our bodies, called CYP2C19.
However, some people have a small change in their DNA which means this enzyme is less effective. Therefore, clopidogrel does not work as well, or at all, to help thin the blood. This genetic change is common in all ethnicities (around 1 in 3 people), but particularly South Asian. This could increase your risk of another stroke.
How does the test work?
The test we use to check for clopidogrel resistance is a cheek swab, whereby some of your saliva is collected and tested in the lab.
You will be visited at your bedside to collect the sample, and we will have the results within the hour.
There is no written form to sign for the test, just your verbal consent.
Further information about the test
Although this is a genetic test, it is only to check for one specific gene. Therefore, no other information will be gathered about your genetics, and it will have no implication on your future health, other than which blood thinner we recommend.
What happens if I am resistant to clopidogrel?
If you are resistant to clopidogrel, firstly, do not worry. There are multiple alternative medications we can provide that will serve the same purpose to thin the blood.
These medications include aspirin, ticagrelor, or dipyridamole. Your doctor will select the most appropriate one, and you can take this instead. If you have any further questions, they will be able to help.
Date of Publication: April 2026
Date of Next publication: April 2028
Ref No: PI_DP_2195 (Salford)