Approximately 4.6 million U.S. adults have a peanut allergy, a new study shows, but only about half have an epinephrine prescription, suggesting diagnosed adults should be more actively educated on how to manage the condition beyond merely removing peanuts from their diet.

Ruchi Gupta and Christopher Warren, members of the Center for Food Allergy and Asthma Research and co-authors of the paper published Tuesday in The Journal of Allergy and Clinical Immunology, arrived at the first detailed estimates of peanut allergy in adults throughout the country.

“There were not really good, solid numbers on food allergies in the adult population. We know it's a growing epidemic in kids, but how is it impacting adults?” Gupta asked.

The study found that the abundance of peanut allergies, specifically, is high among adults. Of 40,000 adults surveyed, 2.9% expressed a self-reported peanut allergy, and 1.8% had what the researchers termed a “convincing” peanut allergy. That means all reported symptoms were in line with standard reactions, technically referred to as Immunoglobulin E antibody, or IgE-mediated reactions.

After augmenting the data accordingly, the colleagues concluded that about 4.6 million U.S. adults have a physician-diagnosed, "convincing" peanut allergy. 

But only about half of those who reported a peanut allergy in any capacity also reported carrying epinephrine. 

Without being treated by epinephrine, most commonly in the form of an EpiPen, an allergic reaction can trigger anaphylaxis, which creates symptoms that range from itchiness and trouble swallowing to more serious ones like fluid filling the lungs and a drop in blood pressure. A blood-pressure drop, if untreated, can lead to anaphylactic shock and sometimes death.

Discussing their findings with The Academic Times, Gupta and Warren both agreed that the first step in solving this allergy epidemic is encouraging adults to get a physician-approved diagnosis if they have a suspected allergy.

As the study illustrates, it is quite common for people to develop allergies in adulthood, not just as kids: More than 17% of those with a peanut allergy first experienced it as an adult. The most common adult-onset allergy is to shellfish, which accounts for more than half of those who express it.

Once diagnosed, the researchers stressed, it is imperative for adults to take the same levels of precaution for themselves, like carrying an EpiPen, that they often take for their children with similar allergies. 

“It's pretty commonly acknowledged that parents and adults are a little more rigorous with the way that they manage their child's condition than the way that they manage their own condition,” Warren said.

The researchers speculate that the lack of epinephrine prescription in adults with an allergy is due to most not seeking out formal testing, even if they have experienced an allergy-like reaction to a certain food, like peanuts, already. 

As an internist herself, Gupta hopes the study's revelation that a surprisingly high amount of adults have a peanut allergy will help other physicians realize the importance of accurately diagnosing their adult patients with allergies, and assisting them in managing the condition medically, if needed.

“I think there are so many things that generalists are dealing with, and this is just one more thing, but the more and more they see it,” Gupta said, “We have to give them the tools to be able to diagnose it.”

Gupta referenced how allergy studies tends to be an elective for aspiring doctors completing their residency. Because of this, she believes it could be a matter of physicians not receiving enough training in the subject, but emphasizes that this is an excellent time to make a change.

“I think now, with the high numbers we are seeing, it's a great opportunity to start building up tools and resources for general physicians to really understand what they should be doing in these cases,” she said. 

The team also underlined that these findings are not limited to peanut allergies. In the paper, they refer to what is called the "top nine," or rather, the most common allergies in adults. 

“The same issues that apply to peanut allergies apply to other allergies as well. It's just as important to get other allergies checked out,” Warren said.

Adults should ensure that if they have a true IgE-mediated food allergy, they are able to "get a management plan, get epinephrine, and know how to use it," Gupta said. "They’re all very, very important pieces of the puzzle.”

The paper, ”Prevalence and characteristics of peanut allergy in US adults,” was published Feb. 9 in The Journal of Allergy and Clinical Immunology. The authors are Christopher Warren, Ruchi Gupta, Dawn Lei and Robert Schleimer, Northwestern University; and Scott Sicherer, Mount Sinai School of Medicine. The lead author was Ruchi Gupta.