UTIs are treated with antibiotics (an-tuh-beye-OT-iks), medicines that kill the bacteria that cause the infection. Your doctor will tell you how long you need to take the medicine. Make sure you take all of your medicine, even if you feel better! Many women feel better in one or two days.
If you don't take medicine for a UTI, the UTI can hurt other parts of your body. Also, if you're pregnant and have signs of a UTI, see your doctor right away. A UTI could cause problems in your pregnancy, such as having your baby too early or getting high blood pressure. Also, UTIs in pregnant women are more likely to travel to the kidneys.
This answer is based on source information from National Women's Health Information Center.