How long does it take for a kidney infection to heal?

It depends: For a simple bladder infection or urinary tract infection (uti), it should get better within 7-10 days with the right antibiotic. If the infection ascended into your kidney (pyelonephritis), this is more serious and you would generally need stronger antibiotics or intravenous antibiotics. This would take between 1-2 weeks to improve. It also depends on your age and strength of your immune system.