Of the estimated 1,300 babies analysed in the study, three in four were found to have “symptoms” by the time they were one year old.
According to current guidelines under the NHS, cow’s milk allergy symptoms in babies can range from skin rashes to digestive problems, such as vomiting or diarrhoea.
However, researchers warned that the official advice may be leading to an “overdiagnosis” of milk allergies, when they were “normal infant symptoms”, such as excessive crying, regurgitation of milk and loose stools.
The study, conducted by researchers at the University of Bristol, found that 38 per cent of three-month-olds and 74 per cent of the 12-month-olds analysed had multiple mild-to-moderate symptoms.
All the participants were from England and Wales, and had been exclusively breastfed for at least their first 13 weeks of life.
Dr Rosie Vincent, lead author of the study, said: “We evaluated the prevalence of guideline-defined milk allergy symptoms in 1,303 infants.
“Guidelines may promote milk allergy overdiagnosis by labelling normal infant symptoms as possible milk allergy.
“There is an assumption the existence of a guideline is more beneficial than no guideline,” she said, adding: “However, well-meaning guidelines need to be supported by robust data to avoid harms from over-diagnosis that exceed the damage of missed and delayed cow’s milk allergy diagnoses that they are seeking to prevent.”
Participating parents reported on their infant’s general health and consumption of foods each month until their children were 12 months of age in a questionnaire for the study.
The findings, published in the Clinical and Experimental Allergy journal, come after a recent investigation found that fewer than one in 100 infants across Europe are actually affected my milk allergies.
Dr Vincent said that nearly three-quarters of the infants analysed had two or more “mild-moderate” symptoms, whereas almost one in ten had “severe” symptoms at some point between three and 12 months old.
“The proportion of affected children was highest at three months of age for both two or more mild-moderate symptoms (37.6 per cent) and two or more severe symptoms (4.3 per cent) when none were being directly fed cow’s milk,” she added.
In 2018, Dr Chris van Tulleken revealed in a BMJ investigation in 2018 that prescriptions for specialist formula for infants with cow’s milk allergies increased by 500 per cent between 2006 and 2016.
Within the same period, the NHS increased its spending on the specialist formulas by 700 per cent, according to the investigation.
Seven out of nine guidelines advise breastfeeding women to cut out all dairy in their diets if they believe their child has a milk allergy.
In England, doctors prescribe about 10 times more of specialist formulas than would be expected based on the proportion of families who use formula milk and the proportion of infants who have a milk allergy.
Dr Vincent said: “The over-perception of food allergy in the general public is long-standing and precedes the emergence of milk allergy guidelines for both adults and children.
“However, guidelines that potentially exacerbate the problem of overdiagnosis are not helpful.”
Additional reporting by SWNS