The answer may be different depending on your other health conditions and the severity of your infection, but most UTI symptoms will start to improve after a few days on antibiotics (maybe even sooner). Your full antibiotic course may be anywhere from 3-14 days. It’s important to take your medication exactly as prescribed. Don’t stop early or you may have a recurrence of the infection or develop a drug-resistant bacteria that can be harder to treat in the future.