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IBS and the menstrual cycle

The irritable bowel syndrome (IBS) occurs more in women than in men and it is likely this has something to do with the menstrual cycle.

During the menstrual cycle, hormone levels fluctuate and may cause a variety of symptoms. Between the end of the period and the time of ovulation, oestrogen is the dominant hormone in the body and the typically symptoms associated with the menstrual cycle do not manifest. Post-ovulation, progesterone becomes the dominant hormone in the body, as its primary function is to protect the embryo if ovulation occurred. A number of symptoms arise as a result of this hormonal change:

1)      Women may experience gut symptoms such as constipation and/or diarrhoea, especially in the week prior to their period

2)      Women may gain weight in the week before their period due to fluid retention leading to swelling (oedema)

3)      The breasts may become especially sensitive and tender, and may enlarge

4)      Women may also experience mood and behavioural changes in the week prior to their period

When these symptoms become severe enough to require medical attention, the condition pre-menstrual syndrome (PMS) is diagnosed.

Many women with IBS report that their symptoms become more severe just before their period.

A possible reason for the link between the menstrual cycle and IBS may lie in the relationship between gut bacteria and the hormone progesterone. This theory was proposed by Professor John Hunter at the National Association for Premenstrual Syndrome, 1995 but has not yet been scientifically verified. He proposed that the increased levels of progesterone influenced the activity of the gut bacteria, resulting in increased malfermentation within the gut culminating in the worsening of IBS symptoms.


In post-menopausal women, treatment is unnecessary as the hormonal fluctuations due to the menstrual cycle stop happening. In younger women, however, the use of oral contraceptive pills may be effective as they reduce the level of ovarian hormones.

Although not scientifically tested, the hypothesis that gut bacteria may be responsible for menstrual related-IBS indicates that dietary approaches may also work to improve IBS-symptoms related to menstruation. A possible approach is to follow the exclusion diet. This involves removing certain foods known to aggravate IBS for a few weeks, and seeing if IBS-related symptoms improve. If they do, then those foods can be re-included in the diet, one at a time, once every 2-3 days, to identify if any food in particular is causing problems. If such a food-item is identified, it should not be eaten.

If there is no change in IBS-related symptoms by following the exclusion diet, then it may be terminated.

Before altering dietary habits, medical advice should be sought. Our consultant gastroenterologists would be happy to review your problems and refer you to one of our expert dieticians for advice if appropriate. Please phone 020 7183 7965 to book your private consultation in one of London’s top private hospitals. If you need further tests such as endoscopy or colonoscopy, we would be happy to arrange these for you also.

We are available to see patients daily.

For a private consultation contact us on
020 7183 7965

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