Doctor, doctor: Dr Tom Smith answers your questions

I am a 17-year-old student on a gap year and was wondering what are the risks, if any, of occasional use of MDMA?

MDMA, or ecstasy, is methylenedioxymethamphetamine. It was used by the German army in the first world war in an attempt to calm soldiers' fears before they went into battle. However, it was quickly discontinued because of its horrendous effects (I hesitate to call them side-effects because they are the main effects of the drug). MDMA stimulates serotonin release from brain nerve cells, giving a 'high' for a few hours. Unfortunately, it also damages those nerve cells - serotonin helps to regulate mood, memory, sleep and appetite, so even if you take just a few E tablets, you run a risk of permanent damage to these vital processes.

And, of course, there are many cases now of sudden death due to excessive temperature rises (hyperthermia) at raves. I worry why you're even considering putting such a dangerous substance into your body. Please don't do it.

Which is it better for your blood pressure to have around the house - a pet or a spouse?

Are you ready for this answer? People with pets have lower heart rates and blood pressure when subjected to stress (such as mental arithmetic problems) than people who do not have them. It is the other way around with a spouse - asked to do arithmetic in front of a partner, blood pressure and heart rate rise faster and more steeply than they would if you were holding your pet. Presumably this may have something to do with the fact that you are not worried that your dog or cat will criticise if you get an answer wrong.

I am 43 and trying to conceive naturally. How long should I give it before I try IVF?

By the age of 43, whether or not you are likely to conceive depends largely on whether or not you are still ovulating. You can easily check that, though - just ask your doctor to do a hormone profile (this takes the form of a simple blood test).

If you are still ovulating, then you should be able to conceive - provided, of course, your partner is fertile, too. If you aren't ovulating, however, then it's more difficult - your doctor will guide you through the steps that can then be taken.

That said, at age 43, you will have to accept that pregnancy and labour are more difficult, and carry more risk to you and the baby than they do at 23.

· Do you have a question for Dr Smith? Email doctordoctor@guardian.co.uk

Thanks to guardian.co.uk who have provided this article. View the original here.