Last time I did it was before I started the azithromycin, and one of the questions was if you were on any antibiotic. I happened to not be on anything just then so was able to give the blood.
FYI, though, when my doctor found out I'd done it, she told me she thought it was a bad idea for my health.
It makes me sad since it's something I would like to do, but with the constant antibiotic disqualifying me as a donor, I don't have to make the decision.