Low-temperature cycles in washing machines don't get rid of some of the most common causes of allergy attacks, say scientists.
Dust mites eat human skin flakes
"Green" energy-efficient 30 or 40 degree celsius washes only killed 6% of house dust mites compared with 100% at 60 degrees, Korean researchers found.
Allergy UK agreed with these latest findings presented at an American Thoracic Society conference.
It advises allergy sufferers use 60 degree washes.
How low can you go?
Washing clothes at 40 degrees compared with 60 degrees uses a third less energy, and many environmental groups, including Friends of the Earth, recommend even lower temperature washes.
Switching from 40 to 30 degree washes saves a further 40% in energy costs, they say.
Modern detergent manufacturers say that their products are capable of cleaning effectively at these low temperatures.
However, the research suggests that this may not be the case.
At both 30 and 40 degree washes, using detergent and 'enzymes' designed to improve washing at low temperatures, between 6.2% and 6.5% of house dust mites were destroyed.
In addition, the low temperature washes fared badly against other allergens.
Cotton sheets contaminated with dog dander - saliva and skin cells that are a common allergen in dog-owning homes - were also washed at 30, 40 and 60 degrees.
At the two lower temperatures, more than 40% of the dander remained when the sheet was re-tested. At 60 degrees, 12% remained.
Likewise, almost 32% of pollen on sheets remained after 30 degree washing, although both 40 and 60 degrees worked far better in this instance.
However, the research team did offer a solution to the problem for consumers determined to run the most energy efficient washes.
They found that rinsing fabrics three or four times in cold water after washing at 30 degrees produced results comparable with a much hotter wash.
Lindsey McManus, from Allergy UK, said the research backed their advice on cleaning regimes for people with allergies.
"Sheets and clothes should definitely be washed at 60 degrees or more, and regularly, to get rid of house dust mite, and other allergens," she said.
John Bailey, from leading detergent manufacturer Proctor and Gamble, said that it wasn't the mites themselves that were causing the allergic reaction, but their droppings.
"House dust mite themselves pose no problems - it's the protein contained in their faecal dropping that's the allergen.
"Under European wash conditions, like other protein allergens, this is easily removed. All effective detergents are successful in removing protein allergens in a 30 or 40 degree wash cycle."
He said that getting rid of the mites themselves did require a different approach - including washing bed linen at high temperatures, getting rid of carpets and fabric covered furniture, or even putting bed sheets in the freezer overnight.