Nearly one in three children has suffered eczema by the age of three-and-a-half, triple the rate in the 1970s, a study suggested last night.
A fifth of babies develop the condition in the first six months according to data on 14,000 children born since 1991.
Researchers cannot yet identify reasons for the rise, although improvements in hygiene may mean that there are fewer chances for babies to develop immunity to the condition, and genetics, environment and diet may also be factors.
The severity of eczema, which may affect around one in 12 adults, varies considerably, with more serious forms leaving the skin broken, raw and bleeding. But it is not contagious.
The study, based on the health development of children being monitored in Bristol University's Children of the 90s project, is thought to be the most comprehensive attempt yet to quantify the problem.
Earlier research has suggested about 10% of children suffered eczema in the 1970s and about 20% in the 1980s.
Researchers are now attempting to analyse lifestyle information to see what puts children at risk.
Nellie Wadonda-Kabondo, one of the team, said: "It is possible that high levels of hygiene these days mean that some children's immune systems are not being challenged enough to develop properly. Changes in diets over recent decades and increasing levels of certain pollutants are other possibilities."
Similar reasons have been given for rises in asthma and hay fever, conditions to which children with eczema are also susceptible.
Margaret Cox, chief executive of the National Eczema Society, which funded the work on the prevalence of the condition, advised parents to use common sense when managing the condition.
She added: "Make sure that you apply lots of medical moisturisers, known as emollients, and if you think that your child has eczema or a rash does not respond to regular moisturising, visit your GP or practice nurse."
Cow's milk, soya, wheat and eggs are among foods which have been linked to eczema. The use of some skin products and nickel allergy are among other causes that have been put forward.
The society says that food is thought to be a trigger in only about a third of cases and it will be the only trigger in only 10% of even these cases. It argues that no allergy tests are 100% reliable.
"Exclusion and challenge", carried out under the supervision of a trained dietician, is the most reliable method. This involves removing all suspected problem food from the diet for up to six weeks, reintroducing it to see if the eczema returns, and, if it does, removing the suspected source again to see whether symptoms improve.
