Urinary Tract Infection
Treat the infection and watch for signs it reached the kidney
General information from an emergency physician. It adds to your discharge papers and does not replace them or your own doctor. What this site is and isn’t
Key Takeaways:
- A bladder infection often improves within a few days. Take the antibiotic exactly as directed. Watch for signs it may be moving beyond the bladder.
- Fever, chills, side or back pain, vomiting, confusion, or feeling faint are reasons to return to the emergency department.
- A positive urine test without urinary symptoms is often not an infection. Antibiotics usually do not help then and can cause harm. Pregnancy and an upcoming endoscopic urinary procedure are important exceptions.
About Your Diagnosis and ED Workup
A urinary tract infection, or UTI, happens when germs enter the bladder. Most start with bacteria that normally live in the bowel. The bacteria travel up the urine tube. They can stick to the bladder lining instead of washing away.
The burning and frequent urge to urinate come from inflammation. The bladder sheds injured surface cells. The body also sends infection-fighting cells there. This is not a hygiene failure. Body structure can help explain repeat infections. So can how easily bacteria stick.
Symptoms and urine testing must be read together. A negative dipstick does not always exclude a UTI when symptoms are classic. A positive test alone does not prove an infection. Bacteria and white blood cells may be present without symptoms. This is common in older adults.
A urine culture is usually not needed for a simple bladder infection with classic symptoms. It is more often needed when the kidney may be involved. It may also be needed if symptoms return or treatment fails. Other reasons include being a man, an older adult, having a catheter, or having a higher risk of resistant germs.
First Steps and Evidence-Based Home Care
1. Follow the antibiotic plan you were given
Different infections need different drugs and treatment lengths. Resistance also differs by area. This page cannot choose an antibiotic for you. Take the medicine on the schedule in your discharge papers. Do not switch to a “stronger” drug on your own.
2. Watch for the culture result if one was sent
A culture may show that treatment should change or stop. In one ED study, many patients needed a culture-based change. Most of those changes were missed. Make sure the care team has a working phone number. Check how results will reach you.
3. Drink enough fluid for normal hydration
For people with repeated UTIs who normally drink little, more water may help. In one trial, adding about 1.5 liters each day cut repeat infections by about half. This is prevention. It is not a cure for the infection you have now. Follow any fluid limits for heart or kidney disease.
4. Do not use cranberry as treatment
Research has not shown that cranberry treats an active UTI. It may modestly prevent repeat infections in some people, but that is a different use. Cloudy or strong-smelling urine alone also does not prove an infection.
Timeline and Expected Recovery Course
A simple bladder infection has a median course of about four days. It usually settles within one week. Clinical cure occurs in about 79% to 90% of cases.
Symptoms that do not improve after 48 to 72 hours of antibiotics need another look. The germ may resist the first drug. The infection may involve more than the bladder. The KB supports culture and reassessment after treatment failure. It does not support choosing a replacement drug at home.
A bladder infection does not always climb to the kidney. Kidney infection is uncommon in women with untreated cystitis. Kidney invasion needs added bacterial features. Still, new fever, chills, or flank pain changes the situation. It needs prompt reassessment.
Emergency Red Flags: Return Immediately
Return to the emergency department for any of these:
- Fever of 38 °C / 100.4 °F or higher, chills, or shaking chills.
- New pain in the side or back near the lower ribs.
- Nausea or vomiting that keeps you from holding down fluids or medicine.
- No improvement after 48 to 72 hours of antibiotics.
- A racing heart, confusion, feeling faint, or other signs that you are becoming very ill.
This list does not cover everything. If you are getting worse or something feels seriously wrong, return to the emergency department.
Reviewed September 3, 2026