Most urinary tract infections (UTI) occur in the lower urinary tract, which includes the bladder and urethra. Cystitis (lower urinary tract infection) is caused when the normally sterile lower urinary tract is infected by bacteria with resultant inflammation. Cystitis is very common.

Most of the time, symptoms of cystitis disappear within 24 to 48 hours after treatment begins. Chronic or recurrent urinary tract infection includes repeated episodes of cystitis (more than 2 in 6 months), or urinary tract infection that does not respond to the usual treatment or that lasts longer than 2 weeks.

In young girls, recurrent urinary tract infections may be an indication of a urinary tract abnormality, such as vesicoureteral reflux, and should be evaluated by a medical care provider. (In boys, even a single urinary tract infection indicates the necessity for evaluation, because urinary tract infections in boys are extremely uncommon in the absence of urinary tract abnormalities.)

The elderly population are at increased risk for developing cystitis due to incomplete emptying of the bladder associated with such conditions as benign prostatic hyperplasia (BPH), prostatitis, and urethral strictures.

Also, lack of adequate fluids, bowel incontinence, immobility or decreased mobility, having a Foley catheter and placement in a nursing home, all place the person at increased risk for developing cystitis.