A wheat bag heat pack has been blamed for setting fire to a bed in north London.
Wheat bags are marketed as a comfortable alternative to a hot water bottle to relieve pain or ward off winter chills.
They are heated in microwaves and popular with the elderly to relieve arthritis, rheumatism and muscle and back pain and makers use cartoons to appeal to children.
But they have been branded "dangerous" after one overheated in a bed in Oxenpark Avenue in Wembley.
'The situation could have been fatal'
A woman suffered from breathing in smoke as she tackled the fire before firefighters arrived and had to be taken to hospital as a precaution.
Two fire engines and around 10 firefighters from Wembley Fire Station were sent to and the fire was was brought under control.
A London Fire Brigade spokesperson said, “The occupant tackled the fire themselves and thankfully was not seriously injured.
"We would always advise people to leave their property immediately upon discovering a fire and to call 999.
“This incident also shows how dangerous wheat bags can be.
"This situation could have quickly escalated and could have been fatal if the woman had been asleep in bed with the bag.
"Wheat bags can continue to build heat once removed from the microwave and start to smoulder; when in contact with bedding a fire can spread quickly.”
Follow manufacturer's instructions
London Fire Brigade warned the wheat bags can be dangerous if not used properly.
Norma Hickey, 83, was believed to be the first to have died after a wheat bag started smouldering among her bed linen and burst into flames in Wallasey Village in 2014.
The products are often used in place of traditional hot water bottles (Photo: Shutterstock)
Firefighters have urged people to always follow the manufacturer's instructions carefully and to ensure a wheat bag is not heated in a microwave for too long or at too high a temperature and is not left unattended at any time.
Fire safety advice issued by Cheshire Fire Brigade said wheat bags available in shops usually contain buckwheat, which has a known moisture content.
Knowing this moisture content and the volume of the wheat bag means that the manufacturer can recommend proper heating times.
It said if you follow the recommended heating time, the bag should not overheat, cause a fire, or burn you.
But homemade wheat bags can pose a greater fire and injury risk because the moisture content and volume of these bags is not known, and the proper heating time can’t be recommended.
And using other types of wheat may increase the risks of overheating, fires, and burns as will adding aromatic oils.
It also warned continual heating and drying of the wheat bag may overheat it to ignition point.
How to properly heat a wheat bag
When heating it in a microwave, place a cup or bowl of water in with the wheat bag to reduce this risk and do not leave it unattended.
They should also watch out for an over-cooked odour, a burning smell, smoking or charring.
And if the wheat bag is kept insulated after heating by placing it under bedclothes for example, spontaneous heating can then occur and the wheat may catch fire.
Consumers are urged not to use the products as bed warmers, and not to reheat them until they have completely cooled on a non-combustible surface, like a kitchen sink, which may be two hours after initial heating.
They should also not be put away until the bag is cold.