Cystitis is a non-contagious urinary tract infection (UTI) that affects the bladder. It's common, particularly in women. Cystitis is a common type of urinary tract infection that causes inflammation in the bladder, leading to mild but unpleasant symptoms like pain when urinating and needing to urinate more often. The inflammation is normally caused by bacteria from poo entering the urinary tract, but it can also happen if you have a problem with your bladder that prevents it from emptying fully.