Advise women with recurrent cystitis that:

• Cranberry products reduce the recurrence rate of cystitis, and are available from shops (but not on the NHS).
• Cranberry products should not be taken if warfarin is being used.
• High strength capsules (containing at least 200 mg of cranberry extract) are recommended because:
• They may be more effective than cranberry drinks, which require a large volume to be drunk to provide the same amount of cranberry extract: 200 mg of cranberry extract is equivalent to about 5000 mg of fresh cranberries.
• Cranberry capsules may be more acceptable than cranberry juice, which some women find difficult to take regularly because of the bitter taste or the large amount of sugar added to mask the bitterness.
• If cystitis is related to sexual intercourse, options to be considered include:
• A different contraceptive method, if a diaphragm is being used.
• Voiding soon after intercourse.
• Using a lubricant if symptoms could be due to mild trauma rather than infection.

Cranberry extract for preventing cystitis

• There is good evidence that cranberry products effectively prevent cystitis. A Cochrane systematic review of randomized controlled trials found that cranberry products significantly reduced the incidence of urinary tract infections (UTIs) over 12 months, compared with placebo or control treatments. However, withdrawal rates in the trials were high, which may indicate that many women find taking cranberry products unacceptable in the long term. Also, the benefits of cranberry may be less in elderly women and women with a urinary catheter.
• The optimal dose and form of administration of cranberry products is not established. However, higher doses may be more effective than lower doses [SIGN, 2006].
• Cranberry products should be avoided by people taking warfarin, as they can potentiate its effects [CSM, 2003; CSM, 2004].

Recurrent cystitis related to sexual intercourse

• These recommendations are based on expert opinion [Harris et al, 2008].
• The Scottish Intercollegiate Guidelines Network (SIGN) guidelines explain that because 'there is no conclusive association between lifestyle factors, such as diet, hydration, clothing, toileting activity, and sexual activity, and susceptibility to bacterial UTI in adult, non-pregnant women, there is no evidence to support healthcare professionals giving routine advice about lifestyle factors' [SIGN, 2006].
• The incidence of UTI may be increased in women who use diaphragms — this may relate to the fit and size of the diaphragm putting pressure on the urethra. The incidence of UTI may also be increased in women who use spermicides, but the use of spermicides with condoms is no longer recommended. For further information, see the sections on Diaphragm and cap, and Male condom in the CKS topic on Contraception.