Reply To: Swab came back negative but the sore looked exactly like herpes

That would do it. Two options from here: if it recurs, go in as early as you possibly can, ideally in the first day or two while it is still fluid filled, and ask them to swab it then. That is the test that actually answers the question.

The other option is a type specific blood test, but discuss the timing with your clinic, because antibodies take time to appear and a test taken too soon after a first episode can be negative while the swab would have been positive.