• Burning or pain when passing urine
• Needing to urinate often or urgently, sometimes only small amounts
• Lower abdominal discomfort
• Cloudy, strong-smelling, or bloody urine

• Fever or chills
• Pain in the back or side, below the ribs
• Nausea or vomiting

Diagnosis

1. Symptoms and history
   • A bladder infection usually causes burning on urination, urgency, frequency, lower abdominal discomfort, or blood in the urine.
   • Fever, chills, nausea/vomiting, or pain in the side/back suggests possible kidney infection, called pyelonephritis.
2. Urine sample
   • Urinalysis or dipstick: looks for white blood cells (pyuria), leukocyte esterase, nitrites, blood, and bacteria. Pyuria supports infection, but does not by itself prove it.
   • Urine culture with antibiotic-susceptibility testing: grows and identifies the organism and helps select an effective antibiotic. It is especially important in suspected kidney infection, pregnancy, recurrent or complicated UTI, UTIs in men, catheter-associated infection, treatment failure, or resistant infection.
   • In a typical nonpregnant woman with first-time, uncomplicated bladder symptoms, clinicians may treat based on the symptom pattern and urinalysis without routinely waiting for a culture. The CDC culture guidance similarly notes that a culture may not be needed for uncomplicated cystitis unless initial treatment fails.
3. Other tests when indicated
   • Pregnancy test, STI testing, blood tests, blood cultures, ultrasound, or CT may be needed when there is severe illness, possible obstruction or stone, repeated infections, poor response to treatment, or concern for kidney infection.

Treatment

Uncomplicated bladder infection

• A clinician prescribes a short course of an appropriate oral antibiotic.
• The antibiotic choice should be based on likely bacteria, local resistance data, allergies, kidney function, and culture results when available.
• Take it exactly as prescribed and complete the prescribed course unless the prescriber changes it.
• Pain relief, hydration according to thirst, and rest may help symptoms. Urinary pain-relief medicines can sometimes be used briefly, but they do not cure infection and should be discussed with a clinician or pharmacist.

Kidney infection or complicated UTI

• Requires prompt medical evaluation and a urine culture.
• Treatment may require a longer course, broader antibiotic coverage, or IV antibiotics and hospital care if the person is very unwell, pregnant, cannot keep fluids down, or shows signs of sepsis.
• An obstruction such as a stone, enlarged prostate, or infected catheter may need separate treatment.

Follow-up

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Current guideline summary

What the latest guidelines specifically recommend

1. Acute cystitis

• Suspected systemic UTI or pyelonephritis
• Atypical symptoms
• Symptoms that persist or recur within four weeks after treatment
• High risk of antimicrobial resistance
• Pregnancy

2. Antibiotic stewardship

• Check prior cultures and resistance patterns.
• Avoid an antibiotic if the person previously had a resistant urinary organism.
• In complicated UTI, avoid a fluoroquinolone if the patient used one in the previous 12 months, unless clinical circumstances justify it.
• Switch from broad empiric therapy to the narrowest effective culture-directed therapy once susceptibility results return.

3. Pyelonephritis and complicated infection

Other useful current guidance

• The UK NICE lower-UTI antimicrobial guideline remains an actively maintained practical source for drug selection and duration, though choices must be adapted to country-specific availability and resistance patterns.
• For children, use pediatric-specific guidance such as NICE UTI guidance for under-16s, rather than adult algorithms.
• A 2024 international evidence review, Nelson et al., JAMA Network Open PMID: 39495518, found that evidence quality remains limited for many UTI decisions. It has a later published erratum, so clinicians should use the corrected record.