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.

In women, the opening of the urethra (the tube that passes from the bladder out of the body) is very close to the opening of the anus. There are often bacteria around the anus, which can be transferred to the urethra. From there, the bacteria can enter the bladder and cause irritation.

In women, cystitis is often caused by transferring bacteria in this way. This can happen when you are:

• inserting a tampon,
• having sex,
• wiping back to front when you go to the toilet (instead of front to back), or
• using a diaphragm (a soft dome made of latex or silicone) for contraception.

In menopausal women, the lining of the urethra and the bladder become thinned due to a lack of the hormone oestrogen. The thin lining is more likely to become infected and damaged. Women also produce less mucus around the vagina after the menopause. Without the mucus, bacteria are more likely to multiply.

Cystitis can also be caused by damage, or irritation, in the area around the urethra. This could be the result of:

• damage caused when changing a catheter (a tube inserted into the urethra to allow urine to flow into a drainage bag, which is often used after surgery),
• damage, or bruising, caused by vigorous, or frequent sex, 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,
• diabetes (a long term condition caused by too much glucose in the blood).

If you have had cystitis before, you may be able to recognise the symptoms and diagnose the condition yourself. You should also seek medical advice if:

• this is the first time you have had cystitis,
• there is blood in your urine (haematuria),
• you have a high temperature (fever) of 38C (100.4F),
• you are in a lot of pain, or
• you have had cystitis three times in one year.

A dipstick to test your urine may be done. This is when a chemically treated strip of paper is dipped into a sample of your urine. The paper will react to the presence of some indicators of infection but it is not diagnostic of infection.

Urine culture

In some cases, a sample of your urine may be sent to a laboratory for further testing. This sample is called a urine culture. This may be necessary if:

• you have recurrent cystitis (more than three times in one year),
• it is possible that you may have a kidney infection - cystitis can be a symptom of this,
• you are on immunosuppressant medication (medication that suppress your immune system) - these affect your body’s defences so you may be more prone to infections,
• you have diabetes (a long term condition caused by too much glucose in the blood) - cystitis can be a complication of diabetes

The urine culture will confirm which bacteria are causing your cystitis.  

Further tests

If you have recurrent cystitis that does not respond to antibiotics, even after a urine culture has been tested, you may be referred to a specialist. You may need to have some other tests such as:

• an ultrasound scan,
• an X-ray, or
• a cystoscopy.

A cystoscopy is when a fibre-optic camera, called a cystoscope, is used to examine your bladder. The cystoscope is a thin, fibre-optic tube that has a light source and a camera at one end. It is inserted into your urethra (the tube that passes from your bladder out of your body) so that images of the inside of your bladder can be transmitted to a screen.

Any further tests that you require will be explained to you by the healthcare professional treating you. 

It is not always possible to prevent cystitis, but there are some steps that you can take to avoid the condition.

• Do not use perfumed bubble bath, soap, or talcum powder around your genitals.
• Have a shower, rather than a bath to avoid exposing your genitals to the chemicals in your cleaning products for too long.
• Always empty your bladder fully when you go to the toilet.
• Do not wait to go if you need to urinate - holding on can place extra stress on your bladder and could make it more susceptible to infections.
• Wear cotton underwear and avoid wearing tight jeans and trousers.
• Always wipe from front to back, not back to front, when you go to the toilet.
• Some people find certain types of food and drink make their cystitis worse - for example, coffee, fruit juice, or spicy foods. If there is anything that triggers your cystitis, you may wish to avoid it.

Although cranberry products are not effective at treating cystitis, they may help to prevent recurrent attacks. High-strength capsules, which contain 200mg of cranberry extract, are available in shops (but not on the NHS).

Cranberry capsules may be more effective than drinking cranberry juice, as you need to drink a lot of juice for it to benefit you, and not everyone likes the taste. Cranberry capsules are not recommended if you are taking warfarin (blood-thinning medication).

Below are some prevention tips that you may find useful if your cystitis is triggered by having sex:

• make sure that you wash your genital area and your hands before and after sex,
• use a lubricant when having sex to avoid damaging your genital area,
• if you use a diaphragm for contraception, you may wish to change to another method of contraception, and
• after having sex, make sure that you empty your bladder as soon as possible to get rid of any germs.

There is currently no evidence that oestrogen products, used to treat women after the menopause, are effective at preventing cystitis.

People who wear catheters need special advice about how to change them without damaging the area. Ask the healthcare professional who is treating you to show you how to do this.