How to avoid false antigen test results

Andalucian pharmacies finally restocked with antigen testing kits
Andalucian pharmacies finally restocked with antigen testing kits. image: wikimedia

How to avoid false antigen test results

Performing a self-diagnostic antigen test at home, without following the correct procedure, can possibly end up with you getting a false result. False negatives or false positives both have different consequences, so it is important that you try and eliminate any chance of getting the wrong result.

The first thing that medical experts ask you to keep in mind when performing an antigen test at home, is to follow the instructions correctly. Maintaining proper hand hygiene, placing the tube in an upright position, and waiting the appropriate length of time before checking the result, are some of the essential guidelines for the correct operation of the test.

In addition to all the instructions given by the pharmaceutical industry itself when carrying out this type of test, there are some actions or reasons why this type of test can produce a false result.


Pharmacy antigen tests have an expiration date. They usually range between four and six months. Therefore, saving antigen tests and running them over time, without checking their expiration date, can give you a strong possibility of a false result.

When taking an antigen test, it should be done at room temperature. Furthermore, the storage temperature of the test is equally important. This is because the reactive liquid is very sensitive, and any extreme temperature could corrupt it.

As explained by Michael Mina, scientific director of eMed, “Do not use rapid tests when it is very cold, as that can decrease their benefits, or their effectiveness”. The temperature at which the self-test must be kept is always indicated on the container itself, and is usually between two and thirty degrees.

Experts advise against taking the test right after eating. The best option would be to wait at least half an hour before undergoing the test.

Especially before a buccal swab test, it is advisable to avoid brushing your teeth, or using any mouthwash beforehand. It is advisable to wait about 20 minutes in case of doing so. Failure to follow this recommendation could lead to a false positive.

Any food or acidic beverage compromise the integrity of the test. In this case, the pharyngeal smear could be affected, and give a positive result, as reported by


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Chris was born in a small village in Wales, where he ran his own successful construction company for many years, before deciding in 1990, to swap the grey skies and rain for the sunshine and lifestyle of the Costa del Sol. Late last year he made the move to Southern Portugal, and is now residing on the Algarve. Having sung and played in a rock band back in Wales, he still likes to go out and entertain in his spare time, singing in restaurants and golf clubs. Interests are of course music, especially from the 60s and 70s, movies, nice restaurants, and he has a passion for graphic design and online marketing.


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