More than 800,000 of these adults – more than 17% – developed an allergy after turning 18, according to a study published Tuesday in the Journal of Allergy and Clinical Immunology.
A peanut allergy has generally been considered a pediatric problem, but more adults than children have allergies, said study author Dr. Ruchi Gupta, director of the Center for Food Allergy and Asthma Research at Northwestern University in Illinois. But only 15% to 20% of children with peanut allergies will overcome their allergy to adulthood, according to the study.
Adults who reported developing a peanut allergy in adulthood were significantly less likely to be diagnosed by a physician than adults who reported developing an allergy in childhood, according to a survey of more than 40,000 American adults.
Gupta said he noticed that adults who have a negative reaction to a certain food tend to avoid consuming it, rather than taking an allergy test. When you are diagnosed with a peanut allergy, you receive confirmation that you are allergic, which affects the way you live your life, she said.
Of the 2.9% of American adults who reported having a peanut allergy, only 1.8% – or 4.6 million people – had a convincing peanut allergy, according to the study.
Convincing symptoms included vomiting, hives and breathing problems, among others, said study author Christopher Warren, a research consultant at the Center for Food Allergy and Asthma Research. Some examples of unconvincing symptoms included bloating and diarrhea, he said.
Adults who self-diagnose also potentially place an unnecessary burden on them to avoid peanuts when they shouldn’t, Warren added.
“They could live their lives as if their next bite could lead to a very bad result when it’s something that would be so easy to avoid,” through routine allergy testing, Warren said.
Another reason it’s important to be diagnosed is that doctors may prescribe epinephrine, said Gupta, which is an emergency treatment for anaphylaxis, a severe reaction to an allergen.
According to the study, only 44% of adults with adult-onset peanut allergy reported prescribing epinephrine, compared with 56% of adults with childhood-onset peanut allergy.
There is no known reason why peanut allergies develop in adults, but a person’s environment or hormones could play a role, Gupta said. She said research is being done to see if a change in a person’s lifestyle or a fluctuation in women’s hormones when they enter puberty or menopause could cause allergies.
What to do if you suspect an allergy
This study found that peanut allergies in adults are more widespread than anticipated, said Steve Danon, senior vice president and head of public affairs and communications at Food Allergy Research & Education, who was not involved in the study.
If you suspect that you have a peanut allergy, Danon has recommended that you consult your primary care physician for testing.
In addition to peanuts, he says you should be tested for common allergens, such as nuts. Adults with peanut allergy with adult onset were more likely to report multiple allergies compared to adults with peanut allergy with onset in childhood, according to the study.
The Food and Drug Administration has not approved any adult peanut allergy therapy, Warren said, but there is therapy for children ages 4 to 17. The therapy slowly desensitizes children to peanuts, which allows them to ingest peanut protein and have a milder reaction or none at all, according to the study.
Another benefit of diagnosis as an adult is that you can participate in peanut allergy therapy tests, Warren said. Clinical trials are an important part of the process for obtaining approval for adult peanut allergy therapies, he said.