A urine infection, medically called a urinary tract infection (UTI), is a bacterial infection anywhere in the system that makes and removes urine: the bladder, urethra, or kidneys. About 60% of women will get at least one in their lifetime, and the vast majority are bladder infections that clear up with a short course of antibiotics. Men get them too, but women develop UTIs up to 30 times more often.
Where the Infection Happens
Most UTIs start when bacteria from the skin or rectum travel up the urethra (the tube you urinate through) and settle in the bladder. This is called cystitis, and it accounts for the large majority of cases. Less commonly, the infection climbs higher and reaches one or both kidneys, a condition called pyelonephritis. Kidney infections are more serious and can make you quite ill.
The bacterium responsible about 90% of the time is E. coli, which normally lives harmlessly in the gut. Other bacteria can cause UTIs, but E. coli dominates because of how close the bowel is to the urinary opening, especially in women.
Symptoms of a Bladder Infection
The classic signs of a lower UTI are hard to miss:
- A burning or stinging feeling when you urinate
- A persistent, urgent need to go, even when little comes out
- Urinating more frequently than normal, often in small amounts
- Urine that looks cloudy, or that appears red, bright pink, or cola-colored (a sign of blood)
- Pelvic pressure or discomfort in the lower belly
You might notice your urine smells stronger than usual, too. These symptoms typically come on quickly, sometimes over just a few hours.
When It Reaches the Kidneys
A kidney infection produces a different, more intense set of symptoms. You may develop a high fever, shaking chills, nausea, or vomiting. Pain tends to settle in the back or side rather than the lower belly. Some people still have the burning and urgency of a bladder infection alongside these upper-tract symptoms, while others feel mainly the fever and flank pain.
Kidney infections need prompt treatment. Left untreated, bacteria can enter the bloodstream and trigger a condition called urosepsis, where the body’s immune response spirals out of control and begins damaging its own organs. Urosepsis can lead to organ failure and, in severe cases, death. Women, older adults, and people with catheters are at higher risk for this progression.
Why Women Get UTIs So Often
Anatomy is the biggest factor. A woman’s urethra is significantly shorter than a man’s, which gives bacteria a shorter distance to travel to reach the bladder. The urethral opening also sits close to both the vagina and the anus, the main source of E. coli.
Beyond anatomy, several things raise your risk:
- Sexual activity. Intercourse can push bacteria toward the urethra.
- Certain birth control. Diaphragms and spermicides can kill protective bacteria that normally keep harmful microbes in check.
- Pregnancy. Hormonal changes alter the bacterial balance in the urinary tract, and the growing uterus can press on the bladder and make it harder to empty fully. Leftover urine becomes a breeding ground for bacteria.
- Menopause. Declining estrogen thins the vaginal tissue, creating an environment where harmful bacteria grow more easily.
- Diabetes. High blood sugar can weaken the immune system and cause nerve damage that makes it difficult to fully empty the bladder.
- Kidney stones or other blockages that trap urine in the urinary tract.
- Catheters. A tube in the bladder can carry bacteria directly inside.
How UTIs Are Diagnosed
Diagnosis usually starts with a urine sample. A dipstick test checks for two key markers: nitrites and white blood cells. Nitrites only appear in urine when certain bacteria are actively breaking down compounds there, so a positive nitrite result is a strong signal of infection. A high white blood cell count points to your body fighting off an invader. In straightforward cases, these results combined with your symptoms are enough to start treatment.
If you get repeated infections, or if a kidney infection is suspected, your provider may send the sample for a urine culture. This identifies exactly which bacterium is causing the problem and which antibiotics will work against it.
Treatment and Recovery
A standard bladder infection is treated with a short course of antibiotics. Most people start feeling better within a day or two of starting medication, though it’s important to finish the full course. For uncomplicated bladder infections, treatment typically lasts three to five days.
Kidney infections and more complicated UTIs require longer treatment, generally five to seven days. Current guidelines from the Infectious Diseases Society of America recommend shorter courses than were traditionally prescribed (previously 10 to 14 days), as evidence shows shorter durations work just as well for patients who are improving on therapy.
While you’re recovering, drinking plenty of water helps flush bacteria from the urinary tract. The burning and urgency usually resolve within the first couple of days of antibiotics, but if your symptoms aren’t improving after 48 hours, or if you develop fever, back pain, or vomiting, contact your provider. That could signal the infection has spread.
Preventing UTIs
If you get occasional infections, a few practical habits can help. Staying well hydrated keeps urine flowing and makes it harder for bacteria to take hold. Urinating soon after sex helps flush any bacteria that may have been pushed toward the urethra. Wiping from front to back after using the toilet reduces the chance of moving bowel bacteria toward the urinary opening.
For people who get frequent, recurring infections, prevention becomes more structured. Current UK guidance from NICE lists low-dose daily antibiotics as one option, though long-term use raises concerns about antibiotic resistance. Vaginal estrogen is another option for postmenopausal women, as it restores some of the protective bacterial environment that declines after menopause. A non-antibiotic antiseptic medication called methenamine hippurate is also recommended as an alternative.
You may have heard that cranberry products or D-mannose supplements prevent UTIs. A well-designed trial funded by the UK’s National Institute for Health and Care Research found that D-mannose made little meaningful difference. Among women with recurrent UTIs, 51% of those taking D-mannose daily sought help for a suspected infection within six months, compared to 56% in the control group. The researchers concluded D-mannose does not prevent UTIs in women presenting to primary care with recurrent infections.
Recurrent UTIs
Some people get UTIs over and over. Roughly defined, recurrent UTIs mean multiple confirmed infections within a year. About 60% of women will have at least one UTI in their lifetime, and a significant portion of those will go on to have repeat episodes. Each infection isn’t necessarily a sign of a deeper problem, but a pattern of recurrence is worth investigating.
Your provider may look for structural issues in the urinary tract, incomplete bladder emptying, or other contributing factors. Treatment shifts from simply curing each infection to building a longer-term prevention strategy tailored to your specific risk factors, whether that involves behavioral changes, topical hormones, or preventive medication.