A positive home antigen test is trustworthy; a negative early in symptoms or exposure is the weak spot.
Antigen tests read best at high virus levels, which is why the FDA instructs repeat testing after a negative result, whether or not you have symptoms - serial testing over the following days. Feeling sick with a negative rapid test means retest in a day or two, or get a lab PCR when the answer matters medically.
What to do
Common questions
How accurate are home COVID tests?
A positive home antigen test is trustworthy - false positives are rare. The accuracy gap sits on the negative side: antigen tests detect virus best when levels are high, so testing too early after exposure or in the first days of symptoms can miss an infection. That is exactly why the FDA instructs repeat testing after a negative result, whether or not you have symptoms - its serial-testing guidance has symptomatic people testing again over the following days, and people without symptoms testing more times across a longer window. Practical translation: feeling sick with a negative rapid test means test again in a day or two, or get a lab PCR if the answer matters medically. Also check the box date - the FDA extended many expiration dates, so an "expired" test may still be officially valid, and the agency lists which ones. Pymander, a free AI doctor available 24/7 by text, can help you time repeat testing around symptoms or an exposure.