Bacterial Cystitis

Overview

Bacterial cystitis is an infection of the bladder caused by bacteria entering through the urethra. It represents the most common type of urinary tract infection (UTI) and predominantly affects women due to their shorter urethral anatomy and its proximity to the anus. Between 20% and 40% of women in the UK will experience bacterial cystitis at some point in their lives.

While men and children can develop bacterial cystitis, it occurs less frequently in these groups. When cystitis is suspected in men or children, prompt medical evaluation is essential, as these cases may indicate underlying urinary tract abnormalities that require investigation.

Symptoms

The hallmark symptoms of bacterial cystitis include burning or stinging pain during urination (dysuria), a frequent need to urinate despite passing only small amounts, and a persistent sense of urgency even when the bladder feels empty. Urine may appear cloudy or darker than usual and often has a strong, unpleasant odour.

Many patients also experience blood in the urine (haematuria), which can appear pink, red, or cola-coloured. Additional symptoms include mild fever with chills, discomfort during sexual intercourse, a dull ache in the lower back or abdomen, fatigue, and general malaise. Nausea may accompany more severe infections.

Causes

Several factors increase the risk of developing bacterial cystitis. In women, the short distance between the urethra and anus makes it easier for intestinal bacteria such as E. coli to reach the bladder. Sexual intercourse can introduce bacteria into the urinary tract or cause mechanical irritation of the urethra, leading to infection.

Catheterisation poses significant infection risk, as the catheter may introduce bacteria directly into the bladder or cause minor trauma that facilitates bacterial colonisation. Contraceptive diaphragms that fit poorly can press against the bladder and prevent complete emptying, creating an environment where bacteria thrive.

During pregnancy, pressure from the expanding uterus may compress the bladder and ureters, leading to incomplete emptying and urinary stasis. Similarly, any condition causing poor bladder emptying increases infection risk, as residual urine provides a medium for bacterial growth.

Post-menopausal women face increased susceptibility due to declining oestrogen levels, which alter the normal protective vaginal flora. Conditions like atrophic vaginitis can further increase UTI risk in this population. Diabetes also predisposes to infection, as elevated glucose in urine promotes bacterial proliferation.

Structural abnormalities in the urinary tract, more commonly identified in young males with repeated infections, may require specialist evaluation. Sexually transmitted infections including chlamydia and gonorrhoea can cause similar symptoms and should be considered in sexually active individuals. See urethritis for more information on urethral infections.

Diagnosis

For straightforward cases with mild symptoms, your GP may initiate treatment based on clinical presentation alone. However, a mid-stream urine (MSU) sample collected in a sterile container allows for laboratory analysis to confirm infection and identify the causative bacteria.

Your GP will typically perform a dipstick test in the surgery, which can detect signs of infection including white blood cells and nitrites. The sample may also be sent for full culture and sensitivity testing, which identifies the specific bacteria responsible and determines which antibiotics will be most effective. This information is particularly valuable if initial treatment fails or if you have recurrent UTIs.

For patients with frequent or complicated infections, referral to a consultant urologist may be recommended for further investigation, which might include imaging studies or cystoscopy to examine the bladder directly.

Treatment

Antibiotic therapy remains the primary treatment for bacterial cystitis. Your GP will prescribe an appropriate antibiotic based on local resistance patterns and, where available, culture results. Common first-line options include nitrofurantoin and trimethoprim. Most uncomplicated infections respond well to a three to seven day course, with symptoms typically improving within 24 to 48 hours of starting treatment.

Increasing fluid intake helps flush bacteria from the urinary system and dilute urine, which may reduce discomfort during urination. Paracetamol or ibuprofen can help manage pain and fever. Some patients find that avoiding caffeine, alcohol, and acidic drinks reduces bladder irritation during recovery.

For mild symptoms in otherwise healthy women, over-the-counter remedies and increased fluids may provide relief while awaiting medical consultation. However, these measures do not eliminate infection and should not replace antibiotic treatment when indicated.

Antibiotic use can disrupt normal vaginal flora and may trigger thrush (candidiasis). If you develop vaginal itching or discharge during or after treatment, discuss this with your GP or pharmacist.

When to See a Doctor

Seek medical attention if you experience symptoms of bacterial cystitis, particularly if symptoms are severe, persist beyond 48 hours, or include blood in the urine. Men and children with suspected cystitis should always consult a doctor promptly, as should pregnant women, who face increased risk of complications.

Urgent medical review is necessary if you develop high fever, severe back or flank pain, vomiting, or rigors (uncontrollable shaking), as these symptoms suggest the infection may have spread to the kidneys, causing pyelonephritis. Kidney infection is a serious condition requiring prompt antibiotic treatment, sometimes administered intravenously in hospital.

If you experience three or more UTIs within a year or two or more within six months, speak with your GP about preventive strategies and specialist referral. Our guide to recurrent UTIs provides further information on managing frequent infections.

Living with Bacterial Cystitis

Bacterial cystitis can significantly disrupt daily life. Frequent urination and discomfort may interrupt sleep, leading to daytime fatigue and reduced productivity. Some patients need time off work while awaiting antibiotic effect.

The association between sexual activity and UTIs can strain intimate relationships. Open communication with partners and strategies such as urinating before and after intercourse may help reduce recurrence. Switching to cotton underwear and avoiding perfumed intimate products can also support urinary health.

Understanding triggers and implementing preventive measures empowers patients to reduce infection frequency. For more information on underlying bladder conditions, see our page on cystitis or explore interstitial cystitis if you experience chronic bladder symptoms without evidence of infection.