Pouring diluted cordial onto a Covid-19 test won’t give an accurate result

2 July 2021
What was claimed

Diluted cordial poured onto a lateral flow test appears to test positive, meaning the tests are a farce.

Our verdict

The tests are not designed to have acidic substances, like drinks, poured on them. This will break the test.

What was claimed

If I drank cordial and then take a test I would test positive because of the drink in my mouth.

Our verdict

Government guidance says you should wait 30 minutes after eating or drinking to take a test to reduce the risk of spoiling the test.

A widely shared post on Facebook claims that lateral flow tests are “a big farce” because pouring some diluted cordial onto one appeared to give a positive Covid-19 result. The poster also claims this means they would falsely test positive after drinking. 

As we have written many times before, the acidity in some foods and drinks can break a test and cause a second line to appear, as if the test were positive. 

This does not mean that the tests are unreliable when used correctly, and it does not mean that the foods and drinks used to break the test are really positive for Covid-19.

Lateral flow tests are unlikely to give a false positive result if used correctly.

To avoid the risk of consumed food or drink affecting the result of a lateral flow test, government guidance states: “Do not eat or drink for at least 30 minutes before doing the test to reduce the risk of spoiling the test.”

We have previously fact checked similar claims about ketchup, oranges, kiwi fruit and Coca-Cola. 

Using food and drinks on lateral flow tests has been in the news after reports that pupils are attempting to get time off school by using liquids like lemon juice to create false positive results.

This article is part of our work fact checking potentially false pictures, videos and stories on Facebook. You can read more about this—and find out how to report Facebook content—here. For the purposes of that scheme, we’ve rated this claim as missing context because this doesn’t show the tests are a farce but it does break them, and you are supposed to wait for 30 minutes after drinking to take a test.

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