Cow’s milk is “increasingly” being identified as the cause of fatal allergic reactions, researchers have said.

It is now the most common cause of fatal food anaphylaxis in school-aged children in the UK, a new study has found.

While the numbers are small, cow’s milk was responsible for 26% of food allergy deaths in school-aged children, experts said.

It comes as a new study found that admissions to hospital for severe food allergies have tripled over the last 20 years.

But the number of deaths from food-related anaphylaxis have reduced.

The research, published in The BMJ, examined hospital admissions in the UK over a 20 year period.

Experts from Imperial College London’s National Heart and Lung Institute studied data from 1998 to 2018.

During this time 101,891 people were admitted to hospitals around the UK for severe allergic reactions.

Of these, 30,700 were due to food allergies.

From the start of the study the rate of people in the population admitted to hospital for anaphylaxis caused by food increased from 1.23 per 100,000 people in the community to 4.04 by 2018.

The largest increase was seen among children under the age of 15, the authors found.

This rose from 2.1 admissions out of every 100,000 people to 9.2 per 100,000 people.

The authors found that 152 deaths were attributed to a severe allergic reaction triggered by food.

But the proportion of deaths decreased over time from 0.7% to 0.19%

Nuts were responsible for 46% of these deaths.

But the authors said cow’s milk was responsible for 26% of deaths in children and 5% in adults, despite allergy to cow’s milk being uncommon in older children and adults.

Cow’s milk was responsible for 17 of 66 deaths in school-aged children.

“Since 1992 a downward trend has occurred in the proportion of deaths due to peanut or tree nut, but deaths due to cow’s milk exposure have increased,” they wrote.

“We observed a concerning increase in fatalities due to cow’s milk, which is now the most common cause of fatal food anaphylaxis in children in the UK.”

Meanwhile the authors point to increased prescriptions of adrenaline auto-injector pens – which help treat severe allergic reactions.

Over the study time period, prescriptions for adrenaline auto-injectors increased by 336%.

But they said that the impact of the increase is “unclear”.

“Hospital admissions for food induced anaphylaxis have increased from 1998 to 2018, however the case fatality rate has decreased,” the authors wrote.

“In school-aged children, cow’s milk is now the most common single cause of fatal anaphylaxis.”

They added: “Most young children with allergy to cow’s milk will outgrow their allergy; however, in those with persisting allergy, cow’s milk is responsible for more than a quarter of deaths caused by food anaphylaxis.”

Tanya Ednan-Laperouse, co-founder of the Natasha Allergy Research Foundation, called for a national register of anaphylaxis deaths.

“This study highlights the urgent need for a national register of deaths by anaphylaxis,” she said.

“Only with a national register can the true picture of the allergy crisis be seen and the voices of those crying out for action, including clinicians as well as families, be properly heard.”