A cure for jetlag?
Q I flew to the States last year and my cousin gave me some melatonin for the flight home. It worked a treat and I had little or no jetlag. This year, we're off to the States again and I want to get hold of some. My GP said it's not available on prescription and our local chemist doesn't stock it. How can I get some, is it safe and is it OK to use as an occasional sleeping pill?
A Melatonin is a chemical made by the brain that helps us regulate our internal clock. It appears to be safe and effective when used in the short term for jetlag. Some hospital doctors also prescribe in order to help unsighted people to get into a "normal" sleep pattern, and to some children with attention deficit hyper-activity syndrome. Your GP can prescribe it for short-term use if he or she feels confident to do so. The risks appear minimal and include reports of headaches in children and a slight increase in fits in some people with epilepsy. It may not work as well for sleep disturbance as it does for jetlag, but it's safer than most sleeping pills.
I can't wear sandals
Q I have a fungal infection of my toenails that is making them look increasingly disgusting. My GP has suggested an oral tablet called Lamisil to be taken for two to three months. I'm a bit reluctant to take anything oral and wondered whether there are any more natural remedies I could try.
A Try tea-tree oil instead. It contains about 100 chemicals, some of which kill bacteria and fungi. Two trials have shown success rates of 60-80% in improving fungal nail infections by using tea-tree oil twice a day for six months.
Q My uncle has just died from prostate cancer. He was only 64 when he died and had always been a fit and healthy man. I am in my late 30s and want to minimise my risk of prostate cancer. I already have an annual check-up which includes prostate tests. Is there anything else I can do?
A Your uncle was unlucky. Although prostate cancer is common, the majority of men who get it are over 65; and while around one in six get it, only one in 30 die of it. African-American men get prostate cancer twice as much as white Americans, though no one is sure why. It may be genetic or diet or something else altogether. If your father or brother - but not your uncle, necessarily - develop prostate cancer, especially under 65, that increases your risk. It's possible that men whose mums have had breast cancer may have a greater risk too.
There is a candidate for a prostate cancer gene called HPC1. The problem is that not everyone who carries the gene will get cancer - and most people who will get cancer don't carry the gene. In time, it may become the basis of a useful test, but not yet.
A high-fat diet may be bad for your prostate because fats increase male hormone levels, which encourage prostate cancers to grow. You can take vitamin E and selenium supplements every day. They're unlikely to cause harm and may give some protection. Eat lots of tomatoes and soy - both contain anti-cancer plant chemicals.
You can have a vasectomy if you want one; contrary to the urban myth, they don't increase your risk. And so to my climax. Regular ejaculation lessens your risk of prostate cancer according to a new Australian study of 2,300 men. Married men ejaculated less than unmarried men of the same age group and their chance of developing prostate cancer was higher. The theory is that ejaculation clears semen from the ducts and stops it becoming cancerous. Don't take the story too seriously, though. Some experts have questioned the ability of men to accurately recall their ejaculations from years before.
These answers are intended to be as accurate and full as possible, but should never be used as a substitute for seeking medical help. If you have a question for Dr Robinson, email firstname.lastname@example.org or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.