Peanut Allergies and Delayed Anaphylaxis

Peanut Allergies and Delayed Anaphylaxis: Signs, Symptoms, and More

Peanut Allergies


Peanut allergies are prevalent in the United States. In fact, about 3 million Americans are allergic to peanuts. If you’re one of them, your immune system will launch an attack anytime it senses the proteins in peanuts. This will cause the release of chemicals that trigger symptoms like itchy hives, nausea, or facial swelling.

Some people have such severe peanut allergies that when they’re exposed to even the tiniest trace of peanuts, they develop a life-threatening total-body reaction called anaphylaxis.


An anaphylactic reaction often starts within seconds after someone with a severe allergy eats peanuts. Sometimes, though, symptoms don’t appear for minutes, hours, or even days after the exposure.

Timeline of an Anaphylactic Reaction

You can be treated for a severe reaction, think you’re perfectly fine, and then develop a second reaction hours later without being exposed to peanuts again. A reaction that occurs long after you’ve been exposed is called delayed or late-phase (biphasic) anaphylaxis.

Learn why this type of response is so dangerous, and find out how to prevent it from happening to you or your child.

Symptoms of a Delayed Anaphylactic Reaction


Symptoms of a delayed anaphylactic reaction can show up an hour or more after you were exposed to the nuts. Some people don’t start to see symptoms until a few days later.

Common anaphylaxis symptoms include:

  • swollen face, eyes, lips, or throat
  • wheezing or trouble breathing
  • weak, fast pulse
  • pale skin
  • confusion
  • sudden feeling of body warmth
  • dizziness or fainting
  • itchy skin
  • hives
  • vomiting
  • diarrhea
  • cramps

The symptoms of a delayed reaction can be more or less severe than symptoms of an immediate reaction.

Dangers of Delayed Anaphylaxis

Some allergic reactions are mild, but anaphylaxis is a very serious condition. Your airways can tighten to the point where you can’t breathe. People with anaphylaxis can die within a half hour if they don’t get medical help.

In some cases, people who’ve been treated for an allergic reaction and seem completely fine develop a reaction hours later. In 2013, 13-year-old Natalie Giorgi ate a small bite of a peanut-laced dessert while on summer vacation with her family. She got three doses of epinephrine, a medicine that helps reverse the symptoms of an allergic reaction. Natalie seemed fine afterward, but she died of a severe allergic reaction later that evening.

Who Gets Delayed Anaphylactic Reactions?

Risk Factors

A study in Annals of Allergy, Asthma, and Immunology found that 2 percent of people treated for an allergic reaction at hospital emergency rooms developed a second, late reaction. That delayed reaction occurred, on average, 15 hours after people were first treated. Another study published in the same journal found that about 15 percent of children had a second severe allergic reaction hours after their first reaction.

You’re more likely to have a delayed reaction if you:

  • have a severe peanut allergy
  • don’t get treated with epinephrine quickly enough
  • don’t get a large enough dose of epinephrine
  • don’t respond quickly to epinephrine
  • have low blood pressure during your first reaction
  • have a history of delayed anaphylaxis

How to Avoid a Reaction


If you know you have a severe peanut allergy, the best way to prevent anaphylaxis is to avoid nuts. Here are a few tips:

  • Every time you shop, read food labels carefully. Packaged foods that contain peanuts are required to include them in the ingredients list.
  • When you order food in restaurants, always let the server know that you have a peanut allergy. Ask for your food to be prepared without peanuts, peanut oil, and other peanut-based products.
  • When traveling by plane, contact the airline and alert them to your allergy ahead of time. You can request that your flight be peanut-free and ask to have your seat cleaned.

As a precaution, always keep an epinephrine auto-injector (such as EpiPen) nearby. This medicine can reverse the symptoms of an anaphylactic reaction, but you have to use it quickly for it to be effective. During a delayed reaction, you may need to administer a second and possibly a third dose. See your allergist to learn how to use the auto-injector correctly.

After you inject epinephrine and your symptoms stabilize, go to an emergency room for treatment. Always get medical help to prevent another reaction.

When to See Your Doctor

when to see a doctor

Anyone who has had an allergic reaction to peanuts should see an allergist. Your doctor will review your medical history and symptoms, give you tips on how to avoid peanuts, and determine whether you need to keep an epinephrine auto-injector on hand for emergencies.

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