Food Allergies in Adults: 9 Facts You May Not Know

It’s surprising how many people think that food allergies are something that only affects children. Food allergies in adults are actually quite common. These can be food allergies that have persisted from childhood or adult onset food allergies that suddenly affect people later in life. We’ve put together some facts about adult food allergies that may surprise you.

#1 – Adult food allergies are reasonably common

Food allergy is generally less common in adults than in children. But the statistics show it is definitely more common than you might think. In Australia and New Zealand, the rate of food allergy by age is approximately:

• 10% in babies;
• 4-8% in children; and
• 2% in adults¹.

According to the American Academy of Allergy & Immunology, approximately 4% of American adults have food allergies (compared to 4-6% of children). Although a 2019 study of just over 40,000 US adults suggested that this figure could be as high as 1 in 10³.

#2 – Adult food allergies can continue from childhood or appear suddenly

Food allergies in adults may be allergies that they have had since childhood. Or, less commonly, adults can suddenly develop new food allergies later in life.

Persistent childhood allergies

Children are often outgrowing common childhood food allergies such as milk and egg later in life than previously, so these allergies may sometimes persist into the teenage years or even adulthood.

When children are diagnosed with allergies to foods like peanuts, tree nuts, sesame and seafood, they are less likely to to grow out of these as they get older. About 75% of children with these allergies won’t outgrow them¹.

Adult onset food allergies

While most adults with food allergies had them as children, many developed new allergies or their first food allergy as an adult.

The 2019 study we mentioned earlier found that of the adults who had food allergies, approximately half of them reported developing at least one food allergy as an adult. About 1 in 4 of the adults in the study developed their first food allergy later in life. This type of sudden onset food allergy can be a shock, especially when it is to a food that you have eaten your whole life without any issues.

We personally know a number of people who have suddenly developed an allergy to fish or shellfish in their 30’s or 40’s, after not having any food allergies at all as a child.

#3 – The most common food allergies in adults and children are different

The top food allergens in Australia are milk, eggs, peanuts, tree nuts, sesame, soy, fish, shellfish and wheat. In children, milk, egg and peanut are the most common cause of food allergies.

The most common food allergies in adults are:

• peanuts;
• tree nuts (such as cashew, pistachio, walnuts, pecans, hazelnut, almond etc);
• fish and shellfish (crustaceans and molluscs); and
• fruits and vegetables (due to pollen allergy, which can cause oral allergy syndrome in some people due to similar proteins in these foods).

However, this does not mean that adults can’t be allergic to common childhood allergens like milk or eggs. In fact, just like children, adults can be allergic to any food at all.

#4 – Symptoms of food allergies in adults are mostly the same as those in children

Symptoms of allergic reactions for both adults and children include:

The most serious type of allergic reaction is anaphylaxis, which can be life threatening.

There are some differences in allergic reactions between adults and very young children. Babies with food allergies may also have symptoms like reflux, diarrhoea or failure to thrive. And infants may be pale and floppy if experiencing a severe reaction¹.

#5 – It isn’t clear why adults develop food allergies

Food allergies occur when the immune system mistakes proteins in food as a threat. The body produces antibodies, which causes the body to respond by releasing chemicals such as histamines which trigger the allergic reaction. It isn’t clear why some people’s immune systems respond in this way – for either children or adults. A family history of allergies or having other allergic disease like eczema and hay fever can increase the risk. But researchers are still investigating why people develop food allergies and why the rate of food allergy is increasing.

#6 – Testing for food allergies is usually the same for everyone

An allergy specialist is the best person to diagnose and manage adults with suspected food allergies.

Tests that an allergist might use include skin prick testing and blood tests to measure IgE levels. You can read more about these types of tests in our post – All about genuine allergy testing – the tests specialists use.

One small difference between testing adults and children is the location of skin prick testing. Children often have tests done on their back, while adults might these on the arm instead.

Allergy diagnosis is more than just having allergy tests. Allergy specialists have the qualifications and experience to decide what to test for, which tests to use and how to interpret test results taking into account your history of symptoms and past reactions.

#7 – Adults have some different food allergy risks

When you have a young child with food allergies, in some ways the risk is easier to control. Parents are usually responsible for supervising children’s activities and safe food choices.

As an adult there are different risks that come in to play. Whether that is:

• eating away from home more often, where others prepare food – this is where food allergy chef cards are a great option;
• drinking alcohol and being aware of possible food allergens in alcoholic drinks; and
• navigating dating and relationships, where its important to have a partner who understands your allergies and knows not to eat your food allergens when they are going to see you (and kiss you!).

#8 – Adult food allergies aren’t likely to go away

Unlike children who frequently outgrow their allergies – especially to foods like milk, egg and wheat – adults generally aren’t so lucky. If a childhood food allergy has persisted into adulthood, it is generally going to be lifelong.

Similarly, if you develop a new allergy as an adult, it is likely that you won’t outgrow it.

#9 – There is less research and treatment of food allergies in adults

You have probably heard about food allergy research in the media, including studies about:

• how to prevent food allergies in babies and young children; and
• treatments to slowly desensitise children to food allergies (such as oral immunotherapy, or the Palforzia peanut patch treatment).

There have been lots of exciting developments in food allergy research in children. And if food allergies can be prevented or treated in children, this will help reduce the number of children whose allergies persist into adult life. But what about adult onset food allergies?

There is very little research being done that specifically focuses on the cause or prevention of sudden onset food allergies in adults. Nor is there much in the way desensitisation or oral immunotherapy trials for adults.

That’s not to say there isn’t any. At the time of writing, St Vincent’s Hospital in Sydney, Australia is recruiting people over the age of 16 with severe peanut allergies for the OPAL Study. This study is combining oral immunotherapy (desensitisation) for peanuts with omalizumab, an anti-allergy medicine.

Hopefully more adult research is to come. And we are hopeful that the findings made in childhood research can be applied to people of all ages with food allergies as more discoveries are made about the cause of food allergy and effective treatments.

In the meantime, the only effective way to avoid reactions is to carefully avoid the foods you are allergic to.

References and where to find more information

If you have been diagnosed with food allergies as an adult, you can find lots of helpful information and access support through your local patient support organisation – such as Allergy & Anaphylaxis Australia or Food Allergy Research & Education (FARE) in the US. You’ll find a helpful list of organisations to contact in our post Allergy support: Why you should join a patient support organisation.

For practical tips in managing your food allergy make sure to read our post about avoiding cross contact in the kitchen. And of course check out our allergy friendly recipes.

You may also be interested in reading some of the the following references that we’ve used in putting together this post:

• ¹Australian Society of Clinical Immunology & Allergy, “Food Allergy – Frequently Asked Questions“
• ²American College of Allergy, Asthma and Immunology, “Food Allergies“
• ³Gupta, RS, Warren, CM, Smith, BM, et al, “Prevalence and Severity of Food Allergies Among US Adults”, JAMA Netw Open. 2019;2(1)

*Disclaimer: Allergy Spot does not provide medical advice. You should always consult a suitably qualified medical practitioner in respect of your own medical conditions, symptoms or concerns. See our Website Terms for more details.