How long does antibiotic treatment take to work for kidney infection?

Fever, chills, pain in the side or back, nausea, and urinary discomfort should gradually settle as treatment works. Tiredness can last longer than the fever. A kidney infection can become serious, so tablets may not be suitable when someone is very unwell, dehydrated, pregnant, unable to swallow, or at risk of complications. A clinician may recommend hospital treatment and antibiotics through a vein in those situations.

Take each dose exactly as directed and complete the course. Drink fluids according to your clinician’s advice, especially if you have heart or kidney problems that limit fluid intake. Rest, and use only pain medicine that is appropriate for you; some anti-inflammatory medicines can be unsuitable with kidney problems. If there is no clear improvement after the expected early response, contact the prescriber promptly.

Seek urgent medical help for confusion, faintness, severe weakness, persistent vomiting, worsening side or back pain, or difficulty passing urine. A fever that persists or returns after starting antibiotics also needs prompt review. Emergency help is needed for facial swelling, wheezing, or trouble breathing after a dose.

Ask how much fluid is suitable for you, whether your other medicines need adjustment, what to do if vomiting follows a dose, and when your urine or symptoms should be reassessed.