According to a study published Tuesday in The Journal of Allergy and Clinical Immunology, more than 800,000 of those adults – more than 17% – developed their allergies after they turned 18 years old.
A peanut allergy is generally considered a pediatric problem, but more adults than children have the allergy, said study author Dr. Ruchi Gupta, director of the Center for Food Allergy and Asthma Research at Northwestern University in Illinois. But according to the study, only 15% to 20% of children with peanut allergies will outgrow their allergies in adulthood.
Adults who reported developing a peanut allergy in adulthood were significantly less likely to be diagnosed by a doctor compared to adults who reported developing the allergy as a child, according to a study of more than 40,000 American adults.
Gupta said she has noted that adults who have a negative reaction to a particular food tend to avoid it instead of taking an allergy test. When you are diagnosed with peanut allergy, you will receive confirmation that you are allergic, which affects how you live your life, she said.
Of the 2.9% of American adults who reported having a peanut allergy, only 1.8% – that’s 4.6 million people – had a convincing peanut allergy, according to the study.
Convincing symptoms included vomiting, hives and difficulty breathing, said study author Christopher Warren, research consultant at the Center for Food Allergy and Asthma Research. Some examples of symptoms that were inconclusive included bloating and diarrhea, he said.
Adults who self-diagnose may also put an unnecessary burden on themselves by avoiding peanuts when not necessary, Warren added.
“They could live their lives as if their next bite could lead to a very bad outcome, when it is something that would be so easy to avoid,” through routine allergy testing, Warren said.
Another reason it’s important to get the diagnosis is because doctors can prescribe epinephrine, Gupta said, which is an emergency treatment for anaphylaxis, a serious reaction to an allergen.
According to the study, only 44% of adults with a peanut allergy in adults reported having received a prescription for epinephrine, compared to 56% of adults with a peanut allergy in children.
There’s no known reason why peanut allergies develop in adults, but a person’s environment or hormones may play a role, Gupta said. She said research is being done to see if a change in a person’s living environment or a fluctuation in women’s hormones when they enter puberty or menopause can trigger an allergy.
What to do if you suspect an allergy
This study revealed that peanut allergies in adults are much more common than expected, said Steve Danon, senior vice president and chief of public affairs and communications at Food Allergy Research & Education, who was not involved in the study.
If you suspect you have a peanut allergy, Danon recommends that you see your doctor to get tested.
In addition to peanuts, he says you should be tested for other common allergens, such as nuts. Adults with a peanut allergy in adults were more likely to report multiple allergies compared to adults with a peanut allergy in children, the study said.
The Food and Drug Administration has not approved any peanut allergy therapies for adults, Warren said, but there is one therapy for children ages 4 to 17. The therapy slowly desensitizes the kids to peanuts, allowing them to absorb the peanut protein and have a milder response or no response at all, the study said.
Another benefit of being diagnosed as an adult is that you can participate in peanut allergy therapy studies, Warren said. Clinical trials are an important part of the process of getting peanut allergy therapies approved for adults, he said.