Doctor explains how fizzy drinks and tap water can give false positives on lateral flow tests

13 January 2022, 12:57

A doctor has revealed how fizzy drinks and tap water can give false positive results (right: stock image)
A doctor has revealed how fizzy drinks and tap water can give false positive results (right: stock image). Picture: TikTok/dr.karanr/Getty

Dr Karan Raj has explained how fizzy drinks and tap water can have an effect on lateral flow tests.

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Lateral flow tests are are now a part of many of our daily routines, and they've been key in helping to slow the spread of coronavirus.

One NHS doctor has outlined why it's important to follow the instructions not to eat or drink 30 minutes before doing their test, as fizzy drinks and tap water can give false positives.

Posting to TikTok, Dr Karan Ranj explained the science behind why this can happen.

As reported by The Sun, he said: "First we need to look inside the lateral flow device.

"This grey box and the portion just above it contain antibodies that are sensitive to the Covid-19 virus.

Dr Rajan explained the science on TikTok
Dr Rajan explained the science on TikTok. Picture: TikTok/dr.karanr

"If you use things like soda, tap water and fizzy drinks, that's going to provide an altered pH, which will affect the function of the antibodies on the test line.

"That is why you need to use this buffer solution (consisting of 99.7 percent saline solution) which provides a stable pH that will actually make the test work."

His words come after another doctor, Dr Nathan Hudson-Peacock, outlined the three mistakes that people make when taking the tests.

As well as not following the instructions to not eat or drink, Dr Hudson-Peacock revealed that some of us are failing to spot faint lines and not testing properly with newer kits. Read more on his advice here.