"Take them off at the hotel, or even some hours afterwards to allow the system to equate again," he said. "When that occurs, the number of people who do get reduced swelling in the legs goes up quite significantly."
When buying compression socks, he says there are different strengths to consider.
"Generally speaking, you should have them fitted, because there are surgical stockings which I call grade 3 and these are approximately 28 through to 32mm of mercury.
"The level most people have and the ones I certainly have are the ones that I think are totally adequate, that are level one, which is about 18 through to about 22 of mercury in that range."
Socks and stockings should be measured around the calf and the ankle – some places where you purchase them will actually do this for you.
As well as wearing compression socks, there are other things travellers can do on a flight to reduce the risk of DVT and swelling.
"During the flight I would recommend getting up and walking around if you can, within every four hours or so and drink a litre of water or more per eight hours of flight." he says.
"I would recommend doing some feet exercises, up and down, round and round with the ankles just to get the muscles moving and getting the pump of the muscles within the calves moving as well.
"Frankly, drugs (such as aspirin) shouldn't be used and this ridiculous flight water that you can buy at the airport, supposedly to adjust the electrolytes, is just a load of crap."
But if swelling does occur, he suggests making use of acupressure points and massage to find relief.
"Some people find it really useful to find a few acupressure points from the big toe and the next toe," he says. "Getting up and walking around, massaging the feet, those sorts of things are the important things to do."
