Health: Pain in the buttocks

DURING TWO pregnancies over the last four years I developed a painful form of acne over my buttocks. This has now happened again, though I'm not pregnant. It makes swimming in public impossible, and rather dents one's libido. My husband urges me to see my GP, but I couldn't bear the embarrassment. Is there anything I can do about it?

Pregnancy sometimes causes strange skin rashes and itches, but not usually painful acne. This type of rash could be caused by an infection, bacterial, viral or even fungal. Another possibility is a rare condition called dermatitis herpetiformis, which is related to coeliac disease. Coeliac disease is made worse by eating foods that contain gluten, such as wheat, and if you are absolutely insistent that you will not see a doctor about this, you could try cutting gluten out of your diet to see whether this helps - but it may take many months before there you see any effect.

A few other ideas are: try an anti-fungal cream such as Canesten which you can obtain from any chemist; use an anti-bacterial skin wash such as Betadine Skin Cleanser. But in the end, it may be better to suffer the embarrassment of showing the rash to a GP or dermatologist.

WHAT ARE the benefits of exercise cycles, and for whom?

Exercise cycles provide aerobic exercise, which is good for the heart and lungs. A recent study in The Lancet showed that middle-aged men who improved their level of physical fitness reduced their death rate by 50 per cent. Regular use of an exercise cycle would be an excellent way of following the example of these men.

Exercise cycles also strengthen muscles and improve circulation in the legs. Any exercise that puts a stress on the bones is a useful way of preventing osteoporosis, and cycling will improve the strength of the leg bones. Exercise is also a potent way of reducing anxiety and depression. So an exercise cycle is beneficial in many ways. Compared with riding a real bicycle, there is the added benefit of not having to contend with car drivers.

YOU RECENTLY suggested "a diet that includes at least five portions of fresh fruit and vegetables a day". How big is a portion? Without a definition, how can I know if I am eating too little, or too much?

A medium-sized apple or banana is a single portion. This usually weighs 125-150g. The same applies to other fruits or vegetables. Don't worry about having too much. Within reason, the more you eat, the better.

Please send questions to A Question of Health, `The Independent', 1 Canada Square, Canary Wharf, London E14 5DL; fax 0171-293 2182; or e-mail to health@independent.co.uk. Dr Kavalier cannot respond personally to questions