Children are at risk of malnutrition from unnecessarily strict diets because their parents have been fooled into thinking they suffer from an allergy, it has been claimed.
Home testing kits which are not backed by science were among the reasons being blamed for the over diagnosis and self diagnosis of allergies, according to newly-published guide Making Sense of Allergies.
Food intolerances and some difficult-to-diagnose conditions have also been confused with allergies, says the guide by Sense About Science which draws on information from allergy specialists and charities.
It also notes that self diagnosis is common, including both among people who do not have an allergy but think they do, as well as those who have had an allergic reaction but blame the wrong cause.
The guide says there is also over diagnosis caused by doctors relying on or misinterpreting limited tests.
It notes a study of 969 children on the Isle of Wight found 34% of parents reported food allergies in their children but only 5% were found to have an allergy.
The guide adds: "This all means that many people get worried about something unnecessarily, take the wrong treatments or avoid the wrong thing.
"Fears about food allergies are leading parents to cut major food groups from their children's menus and causing people to follow unnecessarily restrictive diets.
"It may seem surprising in advanced societies but these are leading to cases of malnutrition, which is particularly risky for children."
The guide states: "Allergy is common, but it is also commonly misdiagnosed and inappropriately treated. Increased discussion and conversations about allergies and the rise of 'free from' products are making people wonder if allergies could be the cause of some health complaint they or their children have. This kind of wondering aloud accounts for many of the online posts about allergy in discussion forums.
"There is such a lot still unknown about allergies, and because even the best allergy tests cannot give an answer that is 100% certain, a space has opened up for companies to offer all kinds of unverified tests and treatments as solutions."
Paul Seddon, a consultant paediatric allergist who works with Cochrane UK, a network of researchers, professionals, patients, carers and people interested in health, said: "I commonly see children who've been put onto unnecessarily restricted diets because their parents assume, in good faith, that they have allergies to multiple foods on the basis of 'allergy tests' which have no scientific basis.
"This needs to stop, which can only happen if we debunk these 'tests'."
In the guide, Asthma UK's director of research and policy Samantha Walker states: "Approximately 30% of the population have an allergy, but many more suffer with non-specific symptoms that are not related to their immune system.
"Whatever the underlying cause, patients want their symptoms to be taken seriously: trivialisation of their condition may turn them towards non-validated tests of dubious value and high cost."
She said that clear unbiased information is "essential to help people make the right decisions about their own health and the health of their family".
Sense About Science director Tracey Brown described the myths, misinterpreted studies and quackery surrounding the over diagnosis of allergies as "probably the biggest mess" for science communication.
She said: "The costs are huge - unnecessary actions for some and not enough action for those whose lives depend on it."