Cystitis is inflammation of the bladder, most often caused by a bacterial infection. It’s the most common type of urinary tract infection (UTI), and it produces that unmistakable burning sensation when you urinate along with a near-constant urge to go. While bacterial cystitis is by far the most frequent form, the bladder can also become inflamed from radiation therapy, chemical irritants, or chronic conditions that have nothing to do with bacteria.
Common Symptoms
The hallmark of cystitis is a painful, burning feeling during urination paired with an urgent, persistent need to pee, even when very little comes out. You may notice your urine looks cloudy or smells stronger than usual. Pelvic pressure or cramping in your lower abdomen is common, and some people develop a low-grade fever or feel unusually tired.
Blood in the urine can happen with bacterial cystitis, though it’s relatively rare in straightforward cases. Visible blood (pink or red-tinged urine) is more common in cystitis triggered by chemotherapy or radiation treatment. In older adults, especially those over 65, cystitis can show up as sudden confusion or mental changes rather than the classic urinary symptoms, which sometimes delays diagnosis.
Children may not describe burning or urgency. Instead, new episodes of daytime wetting in a previously toilet-trained child can signal a bladder infection.
What Causes Bacterial Cystitis
A single species of gut bacteria, E. coli, is responsible for 75 to 90 percent of all uncomplicated bladder infections. These bacteria normally live harmlessly in the intestines but can travel to the urethra and climb into the bladder. Once there, they attach to the bladder wall using tiny hair-like structures on their surface, triggering inflammation. The remaining cases are caused by other bacteria, most commonly Klebsiella, Enterococcus, Streptococcus, and Proteus species.
Women develop cystitis far more often than men, largely because of anatomy. The female urethra is much shorter, giving bacteria a shorter path to the bladder. Sexual activity, hormonal changes during menopause, and pregnancy all increase the likelihood. Men are less susceptible but can still get bladder infections, particularly if they have an enlarged prostate or use a catheter.
Non-Infectious Types
Not all cystitis involves bacteria. Radiation cystitis develops after pelvic radiation therapy for cancers of the bladder, prostate, colon, uterus, or ovaries. Between 23 and 80 percent of people who undergo pelvic radiation experience some degree of bladder inflammation afterward. Symptoms can appear during treatment or months to years later.
Certain chemotherapy drugs can also irritate the bladder lining directly as they’re excreted in urine. And some people develop chemical cystitis from prolonged exposure to irritants like spermicides, feminine hygiene sprays, or bubble baths, though this is less common.
Interstitial Cystitis: The Chronic Form
Interstitial cystitis (also called painful bladder syndrome) is a separate, chronic condition that mimics many symptoms of a bladder infection but produces negative urine cultures every time. The American Urological Association defines it as pain, pressure, or discomfort perceived to be related to the bladder, combined with urinary symptoms lasting more than six weeks, with no infection or other identifiable cause.
The key difference is duration and the absence of bacteria. Where a standard bladder infection clears within days of treatment, interstitial cystitis persists for months or years. People with this condition often experience a constant urge to void and pain that worsens as the bladder fills. Diagnosis involves ruling out infections and other conditions through urine testing, a physical exam, and sometimes cystoscopy (a camera look inside the bladder), particularly if a doctor suspects inflammatory lesions on the bladder wall known as Hunner lesions.
How Cystitis Is Diagnosed
For a standard bacterial infection, diagnosis starts with a urinalysis, which checks for white blood cells, bacteria, and blood in a urine sample. If bacteria are found, a urine culture identifies the specific organism and determines which antibiotics will work against it. The traditional threshold for diagnosing a UTI has been 100,000 colony-forming units per milliliter of urine, a standard established in the 1950s and 1960s. More recent research suggests that much lower bacterial counts, as few as 100 colony-forming units per milliliter, can indicate a true infection in someone with symptoms.
This matters because some people with genuine bladder infections test below the traditional cutoff and get told their results are “normal.” If you have clear symptoms but a negative standard culture, it’s worth discussing lower-threshold testing with your provider.
Treatment and Recovery
Uncomplicated bacterial cystitis is treated with a short course of antibiotics. Current guidelines recommend a few first-line options: a five-day course of nitrofurantoin, a three-day course of trimethoprim-sulfamethoxazole (in areas where bacterial resistance to this drug is below 20 percent), or a single dose of fosfomycin. Most people start feeling noticeably better within one to two days of starting antibiotics, though finishing the full course is important to clear the infection completely.
For non-infectious forms, treatment targets the underlying cause. Radiation cystitis may require medications to manage bleeding and pain, while interstitial cystitis is managed with a stepwise approach that can include dietary changes, pelvic floor physical therapy, bladder training, and various medications depending on severity.
Reducing Your Risk of Recurrence
Some people, particularly women, deal with cystitis repeatedly. Staying well hydrated helps flush bacteria from the bladder before they can establish an infection. Urinating soon after sex reduces the chance of bacteria being pushed into the urethra. Wiping front to back after using the toilet keeps intestinal bacteria away from the urethral opening.
D-mannose, a natural sugar available as a supplement, has growing clinical support for preventing recurrent infections. It works through a simple mechanical trick: the sugar binds to the same structures on E. coli that the bacteria use to latch onto the bladder wall. With those attachment points blocked, the bacteria get flushed out with urine instead of taking hold. Unlike antibiotics, D-mannose doesn’t kill bacteria or contribute to antibiotic resistance, which makes it an appealing option for people dealing with frequent infections.
When Symptoms Point to Something More Serious
A bladder infection that spreads upward to the kidneys becomes a more urgent problem. Back or side pain, high fever with chills, and nausea or vomiting suggest the infection has moved beyond the bladder. This requires prompt medical attention and typically a longer or stronger course of treatment than a simple bladder infection. Similarly, recurrent cystitis (three or more infections in a year) warrants further investigation to rule out structural abnormalities or other contributing factors.