How long does a UTI last?
Last updated September 3, 2026.
With antibiotics, most bladder infections start easing within a day or two and clear in under a week. Untreated, some resolve but many smolder for weeks - and the risk that justifies prompt treatment is the climb to the kidneys, which turns a nuisance into fever, back pain, and hospitalization risk. Fever plus back or side pain on top of urinary symptoms is a same-day call. The CDC's standing advice: take antibiotics exactly as prescribed, finish the course, and drink plenty of fluids.
What to do
- Get the urine test. Burning overlaps with STIs and vaginal infections that need different treatment.
- Finish the antibiotic course. Feeling fine at day two does not end the prescription.
- Hydrate through it. Fluids help flush the bladder during treatment.
- Escalate fever and back pain. Kidney involvement is a same-day evaluation.
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