The ban on carrying liquids in hand luggage has been relaxed at all UK and EU airports.
The new regulations allow passengers to carry on board items such as shampoo, toothpaste and shaving foam as long as they don’t exceed 100ml.
Allowable items include suntan lotions, perfumes, hair gel, mascara, lip gloss and soft drinks.
All liquid containers must be carried in a separate, clear plastic, zip-top or re-sealable bag that does not exceed 20cm x 20cm (8ins x 8ins or one litre capacity).
The plastic bag must be removed from hand baggage at the airport security search and X-rayed separately.
Officials at Heathrow said extra staff would be on duty today to advise passengers of just what they can and cannot carry on board.
Stringent baggage restrictions were introduced at UK airports in August following an alleged plot to blow up aircraft crossing the Atlantic.
The curbs have been gradually relaxed and passengers leaving UK airports for countries other than the US have been allowed to take items such as toothpaste and perfume in carry-on luggage as long as they’re bought after the security checkpoint.
The new regulations have been standardised across the EU, and also apply to airports in the non-EU countries of Switzerland, Norway and Iceland.
Heathrow Airport operator BAA reported slight delays at the west London airport’s Terminal 1 and Terminal 4 this morning.
A spokesman said: ‘There has been fog both in the UK and in Europe today and this has caused some of the delays, including some flight cancellations.
‘We have heavily publicised the new baggage regulations and people seem to understand the new rules.’