I am HIV+ and planning a substantial amount of international travel in the next few months. Any advice?

David King

Dr Jules Eden replies: Travellers who are positive for HIV or in fact anyone who is immunosuppressed, such as post-transplant patients, should think long and hard as to where they go travelling. There are a couple of rules when it comes to having shots. Firstly, any live bacterial or viral vaccine should be avoided. This means the BCG against TB and the live oral polio vaccine are out. There is an injectable inactivated polio vaccine available and that should be used in preference. The yellow fever vaccine poses a bit of a dilemma. It is live and viral, but there is a theoretical risk of encephalitis, or swelling of the brain, as a side effect if given to an immunosuppressed person. So doctors weigh up the balance of the need to travel to a yellow fever area against your ability to avoid mosquitoes, or the real prevalence of yellow fever in an area. It is unlikely in cities for example. Avoid areas where yellow fever and TB are commonly caught, such as central Africa and South American jungles, while being careful in India. Tetanus and typhoid will be fine. For other infections like lung, bowel and bladder, pack a good stock of antibiotics and treat any bugs early and aggressively.

I know jet lag is helped by not drinking coffee and tea. How long before a flight should one stop drinking them?

Sandra West

A: The key to jet lag avoidance is to get your own body clock tuned in to your arrival time as soon as possible. So set your watch for your destination and think "would I be having this at home at the same time?" If yes, go for the espresso; if no, have a Horlicks.

· Dr Jules Eden created E-med as an online support service for anyone who finds themselves a long way from a doctor's surgery. You can get free pre-travel information on any destination in the world. Log on and click on the Travel Clinic icon.

Ask the flying doctor If you have any questions you want to ask Dr Jules Eden, email travel.doctor@theguardian.com, or write to The Flying Doctor, The Guardian, 119 Farringdon Road, London EC1R 3ER.