Great question from Leah!*
The answer: Yes, it is OK! We don’t have evidence that using nose sprays or Neti pots will change your COVID-19 rapid test results!
TL; DR: The SARS CoV-2 rapid antigen tests (aka COVID-19 rapid tests) become positive if they find a lot of the protein that that comes from SARS CoV-2. It is not likely that allergy sprays would change the amount of virus in your nostrils or that its protein would not be detected. In theory a Neti pot or saline spray could do that, but it is unlikely.
🧪 Remember what the COVID-19 rapid tests detect? They look for an antigen (like the nucleocapsid protein) that is part of the 🦠 virus 🦠 (Explanation here). A test result will be positive if you have enough antigen in your nostrils. It is not likely that Flonase, allergy sprays, or saline mist would change how much virus is in your nostrils. A Neti pot could wash out some of the stuff, including bacteria, viruses, and mucus, but there would most likely still be enough viral protein around for the test to detect.
🚥 When you take a SARS CoV-2 Rapid Antigen test, the control line lights up for every test. You put a drop of buffer into the testing unit. The buffer is a neutral solution that does not change when you add an acid or base to it. It is important because it makes sure that the test does not light up unless the SARS CoV-2 antigen is present. BUT, if you alter the buffer, you could get results that are either falsely positive or negative. In fact, there HAS been some talk of acidic substances messing up test results. But this has to do with the testing kit and process and NOT with the sample from your nose (Read the study here.). So unless you are changing the buffer, leaving it out, or mixing it with your solution, you should not have unreliable results.
👃🏽 When you use an allergy spray, it is usually a corticosteroid (like Flonase) that decreases inflammation. This decreases your allergic response. This will NOT have any impact on the presence or absence of the SARS CoV-2 antigen in your nose. However, when you use a Neti pot or saline spray, they are helping to keep your nasal passages from drying out and sometimes helping to unclog a nostril clogged with mucus. In theory, this can wash out a little bit of the viral material, however it is very unlikely that it would do this to the extent that your test results would change (Note: If you use a Neti pot, make sure you do so safely. The FDA alert on this is linked below).
⚠️ If you are worried about a specific nose spray that you are using, check the package insert for the test you are taking. 🧐 Many of the rapid test makers had the same question 🧐 that you did Leah! And so they 🔬 tested a lot of the common nose sprays like Saline and Fluticasone (Flonase). Here’s an example of the package insert for QuickVue (Scroll to page 12 and look for your spray.). Other package inserts list them too, so that is good news. Some of the manufacturers DO recommend that you wait 15-30 minutes after spraying before you take a test. We didn’t find good evidence for why this would be, but it is best to follow the instructions to make sure your results are correct.
The bottom line: It is not likely that your nose spray will change your test results.
Stay safe. Stay well.
Those Nerdy Girls
*Note: We previously answered this question in April of 2022. This post is very slightly modified. There has been very little change or new research on this since 2022.
Avoiding False Positives on Rapid Tests
Full study link on altering test results
FDA link for Neti Pot instructions