A UTI is usually treated with oral antibiotics. There are several antibiotics commonly used- the one chosen by the doctor will depend on local factors (such as bacterial resistance to certain antibiotics in your area), your medical history, and whether you have any allergies to medications. If there is no improvement of your symptoms within 2 days of starting an antibiotic, you should speak to your doctor as soon as possible- as it may be necessary to change to a different antibiotic, and/or to have further tests.