• Follow local guidelines, when these are available.
• If symptoms are severe (for example severe nausea and vomiting, confusion, tachypnoea, tachycardia, or hypotension), admit the person to hospital; intravenous antibiotics may be required.
• If there is fever or loin pain (or both), manage as upper urinary tract infection (UTI) — see the CKS topic on Pyelonephritis - acute.
• Otherwise, treat for lower UTI:
• Obtain a urine sample for culture and microscopy before starting antibiotic treatment.
• Relieve symptoms with paracetamol or ibuprofen.
• Start empirical treatment with trimethoprim or nitrofurantoin:
• Trimethoprim 200 mg twice daily, for 7 days. Trimethoprim should not be used for empirical treatment if the man has a history of recurrent infections or has taken trimethoprim within the past 12 months.
• Nitrofurantoin 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days. The standard formulation is suitable for most people. Consider prescribing the modified-release formulation if nausea has previously been troublesome with the standard formulation, or if adherence with taking medication four times daily is likely to be poor.
• Follow up after 48 hours (or according to the clinical situation) to check response to treatment and the urine culture results.

In depth

• Review after 48 hours (or according to the clinical situation) to check response to treatment and the culture results.
• If urine culture shows that the organism is resistant to the current antibiotic, change to an antibiotic that the organism is sensitive to.
• If symptoms have resolved by the time the culture result is available, consider continuing with the current antibiotic, and doing a 'test of cure' urine culture after completing treatment. If symptoms then recur, treat with an antibiotic shown to cover the infecting organism.
• Consider if there are any risk factors that need to be excluded or managed.
• Consider referral for specialist urological assessment when the man has recovered from the acute infection.

In depth

• Admit the man to hospital if symptoms are severe (for example severe nausea and vomiting, confusion, tachypnoea, tachycardia, or hypotension) — intravenous antibiotics may be required.
• Referral for urological assessment is not routinely required for men who have had a urinary tract infection (UTI).
• Refer for urological assessment men who:
• Have failed to respond to appropriate antibiotic treatment.
• May have an underlying cause for the UTI (such as urinary obstruction, which is more likely in older men, especially if they have hesitancy, straining, or weak urinary stream).
• Have frequent episodes of UTI (for example two or more episodes in a 3-month period).
• Have a history of pyelonephritis, calculi, or previous genitourinary tract surgery.
• Are younger than 50 years of age and have persistent microscopic haematuria with otherwise normal renal function tests (urinary protein and serum creatinine).
• Refer for renal assessment if the man has persistent microscopic haematuria with proteinuria or raised serum creatinine.
• Refer urgently if cancer is suspected. Refer the man to a team specializing in the management of urological cancer if:
• He is of any age, with macroscopic haematuria and urine culture fails to confirm a UTI or the haematuria does not resolve with treatment of the UTI. 
• He is 40 years of age or older, and presents with recurrent or persistent UTI associated with haematuria.
• He is 50 years of age or older, and is found to have unexplained microscopic haematuria.
• An abdominal mass is identified (clinically or on imaging) that is thought to arise from the urinary tract.

In depth

• Culture the urine (whatever the results of urine dipstick tests).
• Treat each episode as for acute lower urinary tract infection (UTI).
• If the man is sexually active, rule out chlamydial infection — see the CKS topic on Urethritis - male.
• Refer for urological assessment if there are two or more episodes of UTI in 3 months.

In depth