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For 54-year-old Nashville native Marbie Sebes, going out to eat isn't easy anymore.

Three years ago, the Nashville hospital administrator had a severe allergic reaction that landed her in the intensive care unit for two days.

“It was August of 2014 and we were having family dinner. We had gone out and purchased shrimp and mahi mahi. We usually do that once a month to treat ourselves, but after dinner I started to feel some real stomach distress,” Sebes said.

“I never felt anything like this before. I had no problems in the past; I ate shellfish … I love shellfish. I ate sushi all the time, shrimp, crab, lobster, all that. Never had any problems with anything,” she said.

But two minutes later, Sebes found herself vomiting uncontrollably. She broke out into hives and a rash that started on her torso quickly spread until she was covered with raised bumps from head to toe. By the time Sebes reached the hospital, she could hardly breathe.

Women prepare shellfish at the Little Saigon Night Market at Asian Garden Mall in Westminster, California. Christine Armario / AP

“I couldn't breathe, I couldn't swallow, my itching was getting much worse, and my tongue was swelling more,” Sebes said.

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“It was terrifying.”

“I couldn't breathe, I couldn't swallow, my itching was getting much worse, and my tongue was swelling more.”

Sebes was eventually injected with an EpiPen and experienced a full recovery. But these near-fatal food reactions are all too common — and on the rise, especially in adults who had never previously experienced allergic food reactions before.

“We have noticed that the prevalence of food allergy has tripled in the last 20 to 30 years,” said Dr. Jonathan Hemler, pediatric allergy and immunology specialist at the Vanderbilt University School of Medicine.

Related: New Peanut Allergy Guidance: Most Kids Should Try Peanuts

"It's very concerning because we don't really have a good explanation as to why this is happening," he said. "Along with the increase in food allergy, we're also seeing more severe anaphylaxis events happening where adults have to go to the emergency room to get treatment."

According to data from FAIR Health, an independent, nonprofit organization focused on transparency in healthcare costs and health insurance information, private insurance claim lines with diagnoses of anaphylactic food reactions rose 377 percent from 2007 to 2016. And half of adults with food allergies developed them after the age of 18.

“We are seeing more adults that have food allergy come into our practice and we're often seeing more severe reactions occurring, adults that needed to go to the emergency room for their reaction, a true anaphylaxis,” said Hemler. “It can be very scary because there’s nothing you can do to predict whether you’re going to have a food allergic reaction.”

Related: Allergic to Peanuts? Tree Nuts May Be OK

The FAIR Health report also found that peanuts were the most commonly identified food causing anaphylaxis, accounting for 26 percent of those claim lines. Tree nuts and seeds were a close second at 18 percent, respectively. The shellfish allergy that affected Sebes was also found to be common, causing anaphylaxis 6 percent of the time.

The most common category, however, was "other specific foods" — 33 percent — which typically means the food causing the anaphylactic reaction is unknown. This category rose 71 percent from 2007 to 2016.

Theories explaining the increase in adult food allergies range from vitamin D deficiency to alterations in gut bacteria due to the combination of a more clean environment and Western diet. Researchers also say that eating too much processed food might also increase one’s risk to develop food allergies.

Doctors are putting a renewed emphasis on the importance of eating a varied diet with lots of fruits and vegetables in hopes that these rates will decrease in the future.

And for patients like Sebes, this is a welcomed development.

“This was a life-changing event, I don't eat out as much. I had to sort of re-learn how to shop because it's amazing how many products that you buy have been manufactured some place where they process shellfish or crustaceans,” Sebes said.

“One wrong bite and I don’t know what would happen," she said. "I just know that I don't want to test it. That’s for sure.”