Can you have a delayed reaction to peanuts?

Some foods can cause delayed reaction. This most often happens in infants who have Food Protein-Induced Enterocolitis Syndrome (FPIES), sometimes referred to as a delayed food allergy. According to the American Academy of Allergy, Asthma and Immunology website, “FPIES is a severe condition causing vomiting and diarrhea. In some cases, symptoms can progress to dehydration and shock brought on by low blood pressure and poor blood circulation.”1

Delayed reactions to peanuts are uncommon but they can occur in rare instances. In fact, delayed reactions caused by FPIES can happen to any food and usually don’t start until hours after a food is eaten.  “FPIES allergic reactions are triggered by ingesting a particular food. Although any food can be a trigger, the most common culprits include milk, soy, and grains.”1 Visit AAAAI website to learn more about FPIES here.

In addition to delayed food reactions, there are also immunoglobulin E (IgE) mediated reactions. If you have an allergy, your immune system overreacts to an allergen by producing antibodies called Immunoglobulin E (IgE).2 For the approximately 1% of people with a peanut allergy, reactions can be serious and potentially life-threatening. Preventing accidental ingestion and avoiding reactions requires consistent and ongoing management. When an individual with IgE mediated food allergy accidentally eats a food that contains their offending allergen (e.g. peanut), a reaction will usually happen within minutes, but can take up to 2 hours.

Anaphylaxis often begins within minutes after a person eats a problem food. Less commonly, symptoms may begin hours later. Up to 20 percent of patients have a second wave of symptoms hours or even days after their initial symptoms have subsided. This is called biphasic anaphylaxis.3

If you have a peanut allergy, your body will work double-time to protect itself from the protein in peanuts that will cause an immune reaction in your body. This is what happens when you have an allergic reaction. The symptoms that occur when your body is in “attack mode” can range from hives to nausea and facial swelling to anaphylaxis. The range of these symptoms can be from mild to life threatening.4 It is important to note that a delayed biphasic reaction seem to be tied to the severity of the initial anaphylactic reaction.5

If you have a peanut allergy, make sure you are always prepared for a reaction by keeping your epinephrine near you at all times. This medication can reverse the symptoms of an anaphylactic reaction, but you have to use it quickly for it to be effective. Any time epinephrine is used, it is important to seek emergency medical attention in case a second round (biphasic) reaction happens, which may require more intensive medical intervention.

You should always consult a board-certified allergist if you have concern about a food allergy. Working with an allergist who is familiar with your health history will assist in managing a food allergy risk.



  1. Moore, A. M. (2020, September 28). Food Protein-Induced Enterocolitis Syndrome: AAAAI. American Academy of Allergy, Asthma & Immunology.
  2. (n.d.). IMMUNOGLOBULIN E (IGE) DEFINITION. AAAAI. American Academy of Allergy, Asthma & Immunology.
  3. Kemp SF. (2008). The post-anaphylaxis dilemma: How long is long enough to observe a patient after resolution of symptoms?
  4. Types of allergies: Food allergy. (n.d.).
  5. Alqurashi W, et al. (2015). Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis. DOI:10.1016/j.anai.2015.05.013