Onion Allergy

Table of Contents

onion allergy

What Is An Onion Allergy?

An onion allergy is an adverse immune reaction to onions. Onion allergy is uncommon but can occur in people of all ages. The main allergens characterized for onion include All c 3 (a lipid transfer protein), All c 4 (a profilin), and All c Alliin lyase. People allergic to onions may also react to edible alliums, such as garlic, chives, scallions, and shallots.

Being sensitive to onion (intolerance) is more common than a true allergy.  An intolerance is caused by an inability to process or digest certain foods. This is not an immune (or IgE-mediated) reaction which excludes symptoms from being categorized as allergy symptoms. If you have a true onion allergy, we recommend visiting an allergy specialist near you. 

Onion Allergy Symptoms

  • Hives
  • Itching
  • Swelling
  • Rhino-conjuctivitis 
  • Asthma
  • Contact Dermatitis
  • Anaphylaxis (rare)

Onions can induce both immediate and delayed reactions. Most cases of onion allergy involve rhino-conjunctivitis, asthma, and contact dermatitis. In rare cases, onion allergy may result in anaphylaxis. One case study identified a 35-year-old man who experienced anaphylaxis after ingesting cooked onions. Anaphylaxis was also reported in another patient after eating raw or lightly-cooked onions, with symptoms including intense itching, urticaria, confusion, blurred vision, transient loss of consciousness, sweating, and tachycardia, which means he suffered a heart rate over 100 beats a minute. It’s important to seek medical treatment as soon as possible if you experience onion allergy symptoms. 

Onion Allergy Diagnosis

An allergist may diagnose onion allergy in many ways, such as through a blood test or food challenge. A blood test measures the amount of onion-specific IgE antibodies in the blood, which indicates whether you are allergic to onions. This is a safe way to test for allergies but results may take a few days to come in. During this time, we recommend patients avoid onions.

In some cases, your allergist may perform an oral food challenge, which involves consuming small amounts of onion under medical supervision to observe for any allergic reactions. A physician will have emergency medical treatment on hand to treat any symptoms that may arise. This test is considered high-risk, so it’s important not to try this challenge at home. 

At New York Allergy & Sinus Centers, we offer a variety of testing methods to diagnose your allergies quickly and safely. Your appointment with us includes a complete allergy exam and test that fits your needs. 

Onion Allergy Treatment

The best treatment for onion allergy is avoidance. If you are allergic to onions, remove them from your diet immediately. You should also carefully read labels before consuming any new food product containing onions. When dining out, ask to see an allergen menu before you order. This will help prevent any allergic reactions.

For severe onion allergy cases, you should also carry an epinephrine auto-injector. Epinephrine is currently the only effective treatment for allergy-induced anaphylaxis. Your doctor can prescribe an EpiPen or Auvi-Q for emergency situations.

For less severe cases, antihistamines can treat your symptoms. Some medications are available over the counter, but you may need a prescription-strength cream or an inhaled corticosteroid. Contact the allergists at NY Allergy & Sinus Centers for personalized treatment options.

Onion Allergy Frequently Asked Questions

Why Are People Allergic to Onion?

The main allergens characterized for onion include All c 3 (a lipid transfer protein), All c 4 (a profilin), and All c Alliin lyase. 

Can I Be Allergic to Onions?

If you show symptoms of an onion allergy, such as contact dermatitis, swelling, or anaphylaxis, you might be allergic to onions. Contact one of our allergists for a proper diagnosis.    

How Is Onion Allergy Diagnosed?

An allergist can diagnose your onion allergy with an allergy test. Call the allergists at NY Allergy & Sinus Centers for a same-day diagnosis of your onion allergy or sensitivity. 

What’s the difference between an onion allergy and a sensitivity?

If you’re allergic to onions, your immune system will identify onions, and possibly other alliums, as dangerous substances and release chemicals like histamine. These chemicals can cause symptoms ranging from uncomfortable to potentially life-threatening. Having an onion sensitivity (or intolerance) is a more common occurrence and is caused by an inability to process and digest specific foods, not by an immune system reaction.

Can Onion Allergy Cause Anaphylaxis?

It is rare, but there have been cases of anaphylaxis caused by an onion allergy. If you’re severely allergic to onion, you should always carry epinephrine.

How Is Onion Allergy Treated?

A food allergy doctor can treat your symptoms with medications, including antihistamines and epinephrine. However, it’s best to avoid onions if you are allergic to them.   

Are There Other Foods Related to Onion That Can Cause An Allergic Reaction?

Foods related to onion that may cause an allergic reaction include edible alliums, such as garlic, chives, scallions, and shallots.