Your health questions answered

Can I reduce my teens' HIV risk?

IS THERE A MORNING-AFTER PILL FOR HIV?

Q. As a parent of two teenagers, I am worried about their risks of contracting sexually transmitted diseases and HIV. Is there an effective "morning-after pill" for HIV which can be taken if a condom breaks and you think there is a risk from your partner?

A. Unfortunately, there is no fully effective "morning-after pill" for HIV, and there is no reliable evidence about the best way of dealing with a risky sexual encounter after it has happened. The good news is that the risk of contracting HIV through a single episode of vaginal intercourse is only about three in 1,000. Anal intercourse is more risky. There is a complicated drug regime that is sometimes prescribed to health workers who are exposed to HIV risk at work. There are no UK guidelines for preventing HIV after exposure in people who are not health workers. If your children think they have been exposed to HIV, they should seek urgent advice from a sexual health clinic or casualty department.

WHY AM I IN SO MUCH PAIN?

Q. Since the birth of my child on New Year's Day 2005, I have experienced muscle and bone pain all over my body. I have been to my GP and have seen a bone/arthritis specialist who arranged an MRI scan on my ankles, but they cannot find anything wrong. A GP friend of mine has told me it may be fibromyalgia, for which there is no cure. The pain gets worse when I am tired. I was perfectly healthy before the pregnancy. I weighed nine stone before the pregnancy and around 12 stone after.

A. Fibromyalgia is a mysterious condition that causes widespread muscular pain and tiredness. Although it is sometimes misrepresented as a psychological problem, it is almost certainly a chronic pain condition that has both physical and psychological manifestations. Unfortunately, there is no simple diagnostic blood test and no simple curative treatment. People with fibromyalgia have tender spots in their muscles, sometimes called "trigger points". If you do not have these tender spots, it is difficult to make a diagnosis of fibromyalgia. There is no recognised connection between fibromyalgia and pregnancy, so I think it may just be a coincidence that the problems started after your baby was born. If you haven't yet returned to your pre-pregnancy weight, you should try to get there. Exercise, especially stretching and gentle aerobic exercise, seems to help. Ordinary painkillers do not work very well in fibromyalgia, but a small dose of an antidepressant often does help the pain (even if you are not suffering from depression). An American website gives an overview of fibromyalgia: www.myalgia.com. The NHSDirect website is also good: www.nhsdirect.nhs.uk (click on health encyclopaedia).

Please send your questions and suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182; or e-mail health@independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions.

Readers write

RK from Leeds was prevented from exercising on an aeroplane recently:

"Flight socks may help prevent DVT, but some gentle exercise on the plane is also good. On a recent flight from the US we were told by the captain to remain in our seats, except for visits to the toilets. Exercising in the aisles was forbidden."