What happens if kidney infection is not treated?

A kidney infection is usually caused by bacteria reaching the upper urinary tract. Pain in the side or back, fever, chills, nausea, cloudy urine, blood in the urine and painful urination can occur. Without treatment, inflammation and infection may progress from the kidney to the bloodstream, causing a life-threatening whole-body response.

The risk is more concerning for people who are pregnant, have diabetes, a weakened immune system, urinary blockage or difficulty emptying the bladder. Kidney infections are different from milder lower urinary infections and should not be managed by waiting for symptoms to pass.

Arrange same-day medical assessment when a urinary infection is accompanied by fever, chills, side or back pain, vomiting or feeling markedly unwell. A urine test can help identify infection and guide treatment. A clinician may prescribe antibiotic treatment and advise how to take it and when to return.

Drink fluids if you can keep them down, rest, and use only medicines that are suitable for you. Do not use leftover antibiotics or stop a prescribed course early without medical advice. A urinary tract infection can travel upwards, so worsening urinary symptoms need review.

Go to urgent care for confusion, fainting, severe weakness, difficulty breathing, persistent vomiting, inability to pass urine, severe flank pain or rapidly worsening fever and chills. Pregnant people, children, older adults and anyone with significant medical conditions should seek advice promptly when kidney infection is possible.

Do my symptoms suggest a kidney infection rather than a lower urinary infection? Should I have a urine test or further assessment? Which antibiotic is appropriate, and when should I expect improvement? What symptoms mean I should return urgently?