Uncertain about your symptoms? A "therapeutic trial" with an antihistamine can help determine if you're experiencing allergies or something else. The US Postal Service offers free at-home COVID test kits, and lab tests can provide a more accurate diagnosis. If you have sinus pain or sneezing, antihistamines may clear up symptoms, indicating allergies.

Source: https://www.cnet.com/health/medical/how-to-tell-flu-covid-allergies/#ftag=CAD590a51e