You don't have to be travelling to Europe these school holidays to be at risk of deep vein thrombosis (DVT).
DVT is a blood clot that forms in the leg which can cause pain, swelling and is potentially deadly.
GP and Melbourne University lecturer Dr Nick Carr said anyone travelling for more than four hours was at increased risk of DVT, including those flying to many Asian destinations.
And it's not just air travel — if you are taking a long-haul bus or train, or travelling for hours by car, you are also at risk.
"When you're sitting still, not moving, legs dangling down, [there's] more risk," Dr Carr told ABC Radio Melbourne's Lindy Burns.
Avoid sleeping tablets, alcohol
Dr Carr warned those taking long-haul flights to resist the temptation to take sleeping tablets.
"You're going to lie there not moving, and that's a significant risk."
He said there were plenty of over-the-counter products nervous flyers could use that were "not going to anesthetise you into inactivity".
Calming your nerves with a gin and tonic, however, was not recommended.
"If you want to get a DVT, alcohol and dehydration is a good way to do it," Dr Carr said.
Aspirin won't help
Dr Carr said he often heard people recommend taking a low dose of aspirin before flying
"The short answer to that is, for most people, don't."
He said there was "not a lot of evidence" that taking an aspirin before flying would prevent DVT, and there could be side effects.
"You can get stomach irritation, bleeding, that sort of thing.
"Aspirin is actually really good at preventing blood clots in arteries ... but for the veins it's not so good."
So what should I do?
Dr Carr said compression socks, sold at chemists and airports, were the most effective prevention against DVT.
"For these things to work they've got to be a little bit uncomfortable because they do have to squeeze you a little bit," he said.
Injections of the blood-thinning drug enoxaparin may help people at high risk of DVT.
This includes people who have had clots previously, people with cancer, and those who recently had leg surgery.
Dr Carr said that while there was no research to support in-chair exercise as a way of preventing DVT, he encouraged his patients to do it anyway.
"I'm a great believer in leg and toe wiggling — why not?
"It doesn't cost anything and it doesn't do any harm."
