Cystitis is inflammation of the bladder that is usually caused by a bacterial infection. Common symptoms include painful urination and frequent urination. Diagnosis involves urinalysis to check for white blood cells or red blood cells. Women are more likely to get cystitis due to anatomical factors that make it easier for bacteria from the intestines to enter the urethra. Treatment typically involves antibiotics, drinking cranberry juice, and preventing future infections by fully emptying the bladder.