Cystitis is a term that refers to urinary bladder inflammation that results from any one of a number of distinct syndromes. It is most commonly caused by a bacterial infection in which cCystitis is an inflammation of the bladder and is most commonly caused by a bacterial infection, making it a type of urinary tract infection (UTI). It occurs when bacteria—often Escherichia coli from the digestive tract—enter the urethra and multiply in the bladder. Symptoms typically include a frequent urge to urinate, burning or pain during urination, cloudy or strong-smelling urine, pelvic discomfort, and sometimes blood in the urine. While cystitis is usually uncomplicated and responds well to antibiotics, untreated infections can spread to the kidneys and cause more serious illness. In some cases, cystitis may also result from irritation, certain medications, radiation therapy, or underlying medical conditions rather than infection. Prompt diagnosis and appropriate treatment help relieve symptoms and prevent complications.ase it is referred to as a urinary tract infection.