The most common signs of a urinary tract infection are a burning sensation when you urinate, a frequent or urgent need to pee (even when little comes out), and urine that looks cloudy, smells strong, or contains blood. Most UTIs start in the bladder, where symptoms stay localized to the lower abdomen and urinary system. But the signs can look very different depending on your age, sex, and whether the infection has spread to the kidneys.
Bladder Infection Symptoms
A bladder infection, the most common type of UTI, produces a predictable cluster of symptoms. You may feel a burning or stinging pain each time you urinate, along with pressure or discomfort in your lower abdomen just above the pubic bone. The urge to urinate can come on suddenly and intensely, and you may find yourself going to the bathroom far more often than usual, only to pass a small amount each time.
Your urine itself often changes. It may turn cloudy or darker than normal, develop a strong or foul smell, or appear pink or red from small amounts of blood. Blood in the urine is common with bladder infections and, while alarming, doesn’t necessarily mean the infection is severe. Fever is uncommon with a straightforward bladder infection. If you do develop a fever, that’s a signal the infection may have moved beyond the bladder.
Signs the Infection Has Reached the Kidneys
When a UTI spreads upward from the bladder to one or both kidneys, the symptoms shift from local discomfort to a more whole-body illness. The hallmark signs of a kidney infection are fever with chills, pain in your back or side (typically on one side, near the lower ribs), and nausea or vomiting. You’ll likely still have the burning and frequent urination of a bladder infection, but the addition of fever and flank pain sets a kidney infection apart.
Kidney infections require prompt treatment because the bacteria can enter the bloodstream. Warning signs that an infection is becoming dangerously serious include a rapid heart rate, fast breathing, very low blood pressure, and difficulty catching your breath. These are signs of sepsis, a life-threatening response to infection that needs emergency care.
How UTI Symptoms Differ in Older Adults
In people over 65, a urinary tract infection frequently shows up without the classic burning or urgency. Instead, the first noticeable change may be sudden confusion or disorientation, a condition called delirium. One systematic review found that delirium appeared in about 29% of older adults with UTIs, making it the most common atypical symptom in this age group. Other non-obvious signs included low blood pressure (in 20% of cases) and a rapid heart rate (in about 11%).
Older adults with UTIs may also experience new or worsening urinary incontinence, drowsiness, loss of appetite, dizziness, or unexplained falls. Fever is often absent, which makes the diagnosis harder. Because older adults frequently can’t report their urinary symptoms clearly, family members and caregivers are often the first to notice behavioral changes like increased agitation, withdrawal, or a sudden decline in daily functioning.
What UTIs Look Like in Infants and Young Children
Babies and toddlers can’t tell you it hurts to pee, so their UTI symptoms are almost entirely nonspecific. Children younger than 2 with a kidney infection may only have a high fever. In full-term infants, studies show fever above 38.5°C appears in 77 to 85% of UTI cases, poor feeding in 48 to 90%, and lethargy in 26 to 30%. Vomiting, diarrhea, and failure to gain weight are also reported.
A fever above 39°C (102.2°F) in an infant is more likely to indicate a serious bacterial infection like a UTI than a viral illness. In older children who can communicate, the symptoms start to resemble those in adults: painful urination, frequent bathroom trips, accidents after being previously toilet-trained, and lower belly pain.
Symptoms Specific to Men
UTIs are far less common in men than in women, and when they do occur, the infection sometimes involves the prostate gland. This overlap means men may experience symptoms beyond the typical burning and urgency. Pain or pressure between the scrotum and rectum (the perineum), discomfort in the testicles or penis, pain in the groin or lower back, and painful ejaculation can all point to a UTI-related prostate infection.
Men may also notice difficulty starting or maintaining a urine stream, dribbling after urination, or a weak flow. Waking up multiple times at night to urinate is another common sign. Because UTIs in men are less expected, they sometimes go unrecognized longer, which increases the risk of the infection spreading to the kidneys.
How a UTI Is Confirmed
Symptoms alone are usually enough to suspect a UTI, but a urine test confirms it. The most common initial test is a urine dipstick, which checks for two markers: one produced by white blood cells fighting the infection, and another produced by certain bacteria. In children older than 6 months, dipstick testing for the bacterial marker is highly accurate, catching infections about 95% of the time with very few false positives. The white blood cell marker is slightly less specific but still reliable as a screening tool.
If the dipstick is positive, a urine culture is often sent to identify the exact bacteria and determine which treatments will work. Results from a culture typically take 24 to 48 hours. In straightforward bladder infections with clear symptoms, treatment often starts before culture results come back.