Cystitis is an infection in the bladder caused by bacteria that usually live harmlessly in the bowel. While children and men can also get cystitis, it is most common in women. Because the infection usually only affects the bladder it is called a lower urinary tract infection (UTI).Cystitis is most often caused by the bacteria known as E coli (Escherichia coli) that get into the urethra from the surrounding skin (the urethra is the tube from the bladder used when passing urine). As the urethra is nearer to the anus in women than it is in men, it is easier for the bacteria to get transferred into the urethra. While cystitis is often very painful, for most women it usually clears up within a few days. However, some women are more prone to getting UTIs than others and may get recurrent bouts.The symptoms of cystitis include a stinging or burning sensation when urinating, the need to urinate frequently or urgently even if you pass very little or no urine, urine that is cloudy or dark coloured, and may have a strong smell or blood in the urine. You may also have pain or tenderness in the lower back or lower abdomen and a general feeling of being unwell. If you have a fever it can mean that the infection has reached the kidneys and you should go to your doctor immediately.As the symptoms of cystitis are very similar to those of other infections such as sexually transmitted infections (STIs) like chlamydia, it is important that you go to your doctor or visit a Family Planning clinic or a sexual health clinic. The doctor will ask you to provide a sample of urine that will be tested on site or sent to a laboratory.