Radiotherapy treatment to the pelvis (for conditions such as cancers of the bladder, prostate, rectum, cervix or womb) can cause temporary inflammation and irritation to the lining of the bladder. This is called cystitis and can lead to passing urine more frequently and pain when passing urine.

Chemicals in cranberry juice help to fight the bacteria, which cause bladder infections and cystitis. So taking cranberry juice or tablets may help to reduce the severity of cystitis, during and after radiotherapy to the pelvis.

It's not clear how often cranberry supplements should be taken or what dose is best. Some doctors recommend a glass or two of cranberry juice per day, during and for a few weeks after radiotherapy.

Caution: People taking Warfarin tablets should avoid cranberry supplements as they can increase the effects of Warfarin causing potentially harmful side effects.

Reference

• Jepson RG, Mihaljevic L, Craig J. Cranberries for preventing urinary tract infections. The Cochrane Database of Systematic Reviews 2004, Issue 2.