Medically reviewed on May 17, 2023 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Consuming certain foods such as nuts, milk, or wheat can trigger severe immune reactions in some people. To fend off the unwanted invader, the body releases antibodies that can bind to certain immune cells to release a variety of chemicals like histamine, a chemical that’s responsible for many food allergy symptoms. 
So, how long does a food allergy reaction last? Depending on the type of food allergy you have, symptoms of food allergies may arise in various parts of the body, including the gastrointestinal tract, the lungs, and the skin, among others. In some cases, reactions can be life-threatening. However, milder cases are more typical and usually resolve in a few hours. 
To better understand the relationship to certain foods and potential food intolerances, the six most common food allergy symptoms and how they may manifest in the body are outlined below.
Food allergy symptoms will depend on the type of food allergy experienced. There are two types of food allergies: immunoglobulin E (IgE)-mediated food allergies and non-IgE-mediated food allergies.
Typically, food proteins will impact IgE levels. 
IgE refers to the antibody known as immunoglobulin E, which plays a key role in allergic reactions. It’s produced by the immune system and, upon ingesting an allergen, will disperse and bind itself to mast cells and basophils in the body. 
Mast cells are types of white blood cells found in the connective tissues of the skin, lungs, and intestines.  Basophils, on the other hand, are immune cells in the blood that release certain enzymes and chemicals during an allergic reaction.  As such, when IgE binds to these types of cells, chemicals, like histamine are expelled, and food allergy symptoms are triggered.
Symptoms develop rapidly and usually occur seconds or minutes after ingesting the allergen.
Typically, an IgE-mediated food allergy is confined to one part of the body. In some cases, it may affect multiple parts of the body, which can include: 
IgE-mediated food allergies might also lead to anaphylaxis—a serious-to-life-threatening allergic reaction that can cause breathing difficulties, increased heartbeat, and loss of consciousness. 
Non-IgE-mediated food allergies, on the other hand, can lead to subacute or chronic inflammatory responses in the gut and gastrointestinal system.  These allergic symptoms usually take time to develop and may become chronic. 
These reactions are triggered by immune system components outside of IgE. Instead of IgE, T cells react to the allergen, or food protein, and trigger an immune response. That said, non-IgE-mediated food allergies are less understood than IgE-mediated food allergies and a lack of laboratory testing measures make it difficult to identify this type of reaction in people. 
Fortunately, researchers have identified that this type of food allergy is rarely life-threatening and will not cause anaphylaxis. 
All that said, some people can experience both IgE-mediated allergies and non-IgE-mediated allergies, particularly if they have a history of eczema. 
So, what are the most common signs of food allergies to look out for? Let’s explore.
As previously mentioned, non-IgE-mediated food allergies can impact the gastrointestinal tract and trigger a variety of food hypersensitivity syndromes, such as: 
An IgE-mediated food allergy can trigger allergic reactions to the skin since mast cells are found in the vascularized tissues under the skin.4 Patients with these symptoms can experience: 
Skin reactions to non-IgE-mediated food allergies are less common, but can still occur—such is the case with Celiac disease. That said, it’s important to note that skin reactions can also be caused by other factors as well, such as medications, insect bites, or exposures to irritants, so it’s important to seek medical attention to determine the cause of the skin reaction.
An inability to breathe is a common symptom of a severe allergic reaction, particularly in IgE-mediated food allergies. When a person with an IgE-mediated food allergy consumes an allergen, their immune system releases histamine, which can cause inflammation and narrowing of the airways in the lungs.
Respiratory-related symptoms may include: 
Similarly, an IgE-mediated food allergy can trigger fainting or loss of consciousness, as a result of, or separate from anaphylaxis. More specifically, activation of the histamine receptors H1 in the brain cells, muscle cells, and blood vessels can cause hypotension, or low blood pressure. 
As a result, the brain, heart, and other parts of the body don’t receive enough blood, which can cause: 
Extremely low blood pressure can also lead to shock, which can lead to cold, clammy skin, rapid, shallow breathing, and a weak pulse. 
Mild-to-moderate IgE-mediated food allergies can occur, specifically in the case of oral allergy syndrome (OAS). This type of allergic reaction is triggered when raw vegetables, fruits, or nuts come in contact with the mouth or throat.
The most common symptoms include itchiness or swelling of the: 
Some people may also experience hoarseness or trouble speaking. Researchers also found that seasonal allergies may impact certain food intolerances. For example, those who are allergic to airborne birch tree pollen may also be sensitive to pitted fruits or carrots. 
In the most severe IgE-mediated food allergies, individuals can experience anaphylaxis. This occurs when IgE binds to immune cells and too many chemicals are released, which can put a person into shock. 
Symptoms can manifest quickly.  They can also last for up to 12 hours after the initial reaction. While early symptoms are mild—such as a runny nose or a skin rash—they can quickly develop into more life-threatening allergic reactions if left untreated.
These can include: 
If you have a history of anaphylaxis or more severe IgE-mediated food allergies, it’s crucial to carry an epinephrine injectable pen with you. Epinephrine, or adrenaline, can help relax your muscles and reopen the airways. That said, if you or a loved one experience anaphylaxis, it’s also critical to visit a healthcare facility in which a healthcare professional can continue to monitor your condition.
The best way to prevent a food allergy reaction is to avoid foods that you’re sensitive to. Often, blood tests that monitor for antibody reactivity for IgE or Immunoglobulin G (IgG) can help guide you on what foods and proteins you should avoid.
However, researchers also believe that some factors may prevent the onset of certain food allergies. In a 2015 study, 640 children believed to be at high risk of a peanut allergy were enrolled into a clinical trial to assess possible prevention. 
Half of the children avoided all peanuts until they were five years old. The other group was given peanuts three times a week until they turned five. It was found that the children who were exposed to peanuts were 80% less likely to develop a peanut allergy. 
As such, it’s believed that regular exposure to certain allergens may decrease the likelihood of developing a food intolerance, or, at the very least, dampen the symptoms if an allergic reaction does occur.
See related: Are Food Allergies Genetic?
Depending on the type of food allergy you have, symptoms will vary. Those with IgE-related food allergies might experience various effects throughout the body, from skin rashes and difficulty breathing, to oral tingling and anaphylaxis.
Conversely, those with non-IgE-mediated food allergies may only experience gastrointestinal issues, such as vomiting, bloating, and diarrhea. This type of food allergy can also develop into food hypersensitivity syndrome.
Fortunately, Everlywell offers two at-home blood tests to help assess your immune responses to certain proteins found in foods. The Food Sensitivity Test assesses IgG reactivity, while the Food Allergy Test assesses IgE reactivity to common food allergens, such as cow’s milk, peanuts, and wheat.
Take a proactive step toward your health and unlock peace of mind with Everlywell.