THE National Blood Service is appealing for people to Give Before You Go.
As the holiday season reaches its peak, the amount of blood donated drops.
People who aren't already donors are being encouraged to think about giving blood for the first time to ensure that blood levels are not dramatically affected.
Those planning holidays to exotic locations are also being asked to give now as they may be prevented from donating for up to six months after their return.
The campaign is being supported by TV chef Gordon Ramsay, who said: "It is vitally important that we all remember to give blood before we go on holiday.
"As our thoughts turn to booking a holiday and jetting off to the sun, make sure that you remember to donate blood before you go away.
"If you've never given blood before take just take a few minutes out of your busy day to register your details on the register.
"One donation of blood can save more than one life, and if you're an existing donor then remember that you can give blood up to three times a year."
Donors sessions are being held at Homebase in Victoria Road, South Ruislip, from 9.30am to 12.30pm and 2pm to 4.30pm Monday, August 14, and at Ealing Town Hall on Wednesday, August 16, from 9.15am to 12.30pm.
Donors should be aged 17 to 60, in general good health and weigh over 7st12.
Nationally, the NHS needs 8,000 units of blood every day, and in London and the south east alone it needs 438,000 donations a year.
Last year, the National Blood Service collected 2 million donations from about 1.3 million people, but that's only 5 per cent of the population, giving two or three times a year.
For more information, call the all the Donor Helpline on 0845 7 711711 (24 hours) or see www.blood.co.uk