The most common cause of cystitis is a bacterial infection. If bacteria reach the bladder, they can multiply and irritate the bladder lining, causing the symptoms of cystitis.
Cystitis can also result from damage or irritation around the urethra. The urethra is the tube that carries urine from the bladder out of the body. In men, the urethral opening (where urine leaves the body) is at the tip of the penis. In women it's just below the clitoris.
Bacterial infection
This happens when bacteria get into the bladder and multiply. It can happen if you don't empty your bladder properly. Try to empty your bladder fully each time you go to the toilet, to help prevent bacterial infection.
You may not be able to empty your bladder fully if:
- you have a blockage somewhere in your urinary system: this could be caused by a tumour or, in men, an enlarged prostate (a gland located between the penis and the bladder)
- you are pregnant, as pregnancy puts pressure on the pelvic area and the bladder
Bacterial infection can also happen when bacteria from the anus are transferred to the urethra. This is more common in women than in men, as the urethra is closer to the anus in women than it is in men.
In women, transferring bacteria in this way can happen when you are:
- having sex
- wiping after going to the toilet (you're less likely to transfer bacteria in this way if you wipe from front to back)
- inserting a tampon
- using a diaphragm (a soft dome made of latex or silicone) for contraception
In women who have had, or are going through, the menopause, the lining of the urethra and the bladder become thinner. This is due to a lack of the hormone oestrogen. The thin lining is more likely to become infected or damaged. Women also produce fewer vaginal secretions after the menopause, which means that bacteria are more likely to multiply.
Damage or irritation
Cystitis can also be caused by damage or irritation in the area around the urethra in both men and women. This could be the result of:
- damage or bruising caused by vigorous or frequent sex (this is sometimes called honeymoon cystitis)
- wearing tight clothing
- chemical irritants – for example, in perfumed soap or talcum powder
- other bladder or kidney problems, such as a kidney infection or prostatitis
- diabetes (a long-term condition caused by too much glucose in the blood)
- damage caused by a catheter (a tube inserted into the urethra to allow urine to flow into a drainage bag, which is often used after surgery)
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