Can urinary tract infection cause kidney infection?

A bladder infection usually affects the lower urinary tract. If bacteria travel through the ureters, they can infect one or both kidneys. Kidney infection may cause fever, chills, pain in the back or side below the ribs, nausea, vomiting, or feeling markedly unwell. Burning urination, frequent urges, or cloudy urine may occur as well. Symptoms can overlap with a bladder infection, so the change in pattern matters.

A kidney infection is different from ordinary bladder discomfort because the infection involves tissue higher in the urinary system. Untreated infection can become more serious, particularly in pregnancy, in children, in older adults, or when urine flow is blocked by a stone or another problem.

Contact a clinician promptly if urinary symptoms are accompanied by fever, side or back pain, vomiting, or a rapid decline in how you feel. A clinician may check a urine sample and decide whether treatment is needed. Take prescribed medicine exactly as directed and do not use leftover antibiotics. Drink fluids if you can keep them down, unless a clinician has told you to restrict fluids. Rest and note when symptoms began, whether they are worsening, and any medicines you have taken.

Seek urgent medical help for confusion, unusual drowsiness, difficulty breathing, fainting, severe weakness, persistent vomiting, or severe pain. Get same-day advice for fever with urinary symptoms, shaking chills, blood in the urine, pregnancy, or known urinary blockage. These signs can indicate that the infection is affecting the kidneys or the whole body and should not be watched at home.

Ask whether your symptoms fit a bladder infection or kidney infection, whether a urine test is needed, and how quickly treatment should start. You can also ask which symptoms should bring you back, whether any regular medicines change your care, and when improvement should be expected.