Difficulty breathing Archives - Lifelab Testing

Onion Allergy Guide

An onion allergy occurs when your body mistakes onions for harmful substances. This, in turn, triggers the immune system to release antibodies to fight the “harmful” substance, and that’s when we witness onion allergy symptoms such as itchiness, vomiting, trouble breathing, and others. Onions are a common ingredient in salads and all cooked meals. It is hard to come across a restaurant or home where onions aren’t used as a primary ingredient in making stews, curries, and stir-fries. This is why it can be challenging to manage an onion allergy.

When suffering from onion allergy, different people get affected in varying ways. For example, one may get a reaction from smelling or touching onions or consuming onions, whether raw or cooked. While some people get reactions from only smelling, touching or eating raw onions (raw onion allergy), others get the same symptoms from cooked onions. Onions are part of the genus allium, which also consists of shallots, leeks, garlic, and chives. If you’re allergic to onions, it is possible to get the same reaction with other plants in the allium family. Sometimes, it may not be an allergic reaction but rather a sensitivity. This cross-reactivity is because these plants contain similar internal makeup, which the immune system can mistake for onions, producing the same immune attack resulting in onion allergy symptoms.

Not all alliums are edible; others are ornamental (inedible) and may trigger a reaction in some people through touch. If you’re allergic to onions, this means that you’ll react to all types of onions. For example, you’ll also suffer from a red onion allergy and a spring onion allergy. There won’t be any exceptions to the types of onions you’ll react towards.

Onion allergy symptoms

A woman holding her stomach.

Symptoms of onion allergy vary from one person to the other regarding mildness and severity. Once you smell, consume or touch onions if you’re allergic, you can expect symptoms to show up immediately or within a span of two hours. There are, however, others who may not experience the allergy symptoms for a few more hours. If you’re allergic to onions, you will experience a few of these symptoms that may be internal or external. These common symptoms of onion allergy include:

  • Itching and tingling in the mouth.
  • Hives or rashes all over the body.
  • Nausea and vomiting.
  • Swelling of lips, tongue, lips, face, or throat.
  • Difficulty breathing.
  • Nasal congestion.
  • Stomach pain.
  • Diarrhoea.
  • Gas.

The above symptoms often are mild and can be easily managed by home treatment. However, if you experience severe gastrointestinal issues, it is wise to visit a doctor. It is common for the symptoms to stop once the onions have left your body. In rare cases, however, onion allergy can result in life-threatening symptoms. Anaphylaxis associated with onion allergy has been reported before after consuming raw onion {1}. When one experiences anaphylaxis, there is a dire need to immediately access medical help, as this condition can easily take one’s life. There are specific symptoms you can witness that will help diagnose anaphylaxis. These are:

  • Confusion.
  • Dizziness.
  • Trouble breathing.
  • Low blood pressure.
  • Loss of consciousness or fainting.
  • Sweating.

Upon getting urgent care, a doctor will prescribe an Epinephrine pen (EpiPen). One should always carry this in person in case there are any accidents and anaphylaxis occurs. If you’re with someone and you can see they’re suffering from anaphylaxis, use an EpiPen if they have one and still rush them to the emergency room for observation. Observation is essential since these symptoms can recur after a few hours, so it’s best to stay under the doctor’s care.

Onion and garlic allergy

If you’re suffering from an onion allergy, it is common to find that you’ll have the same reaction to garlic. These two ingredients are from the same genus (allium), which means the proteins in these foods are similar, and the body mistakes one for the other. This confusion that goes on in the immune system is known as cross-reactivity. You may also find that you’ll have the same allergic reaction to other alliums like chives, shallots, leeks, and scallions. The cross-reactivity level for different vegetables in this genus varies amongst different individuals.

Onion Intolerance

Our Complete Intolerance Test Box.

The most common and well-known reaction to onions is intolerance. Onion intolerance often comes with many gastrointestinal symptoms. Often with onion intolerances, you may find that you have an underlying condition that is leading to all the gastrointestinal mishaps. In such cases, you’ll need treatment for the core ailment, which could eliminate the intolerance. However, in other cases, you’ll find that your doctor won’t be able to see any underlying conditions that could be leading to symptoms similar to the ones we’ve mentioned. It can be difficult to determine which food is causing an intolerance, as symptoms can occur days after consuming the problem food. To be sure which food item is causing symptoms, you could take an Intolerance Test. Our complete intolerance test looks at reactions to onion, garlic and 157 other items.

Onion Allergy Testing

If you have a reaction every time you consume onions, you should see your doctor, give them your history, and explain your symptoms. If you’re experiencing allergy symptoms but are unsure what is the cause, you may benefit from taking an allergy test. An allergy test will check your sample against all common allergens in your food and immediate environment then we’ll send you a list of the foods you need to avoid because you’re allergic.

Our allergy test is ideal since you don’t have to make a doctor’s appointment or wait in their office for hours on end to know what’s causing your symptoms. You can order easily online, get delivery within three days, take a sample, and once you send it back you’ll have your results within seven days via mail. With this test, you don’t have to stop working because we’ll take care of everything else while you have an uninterrupted life.

Foods that can cause onion allergy

When suffering from an onion allergy, you must avoid alliums, including shallots, garlic, chives, mugwort tea, leeks, and scallions. Avoiding all of these is the easiest way to prevent getting any symptoms. However, it can be very difficult to avoid onions since they’re in many processed, prepared, and packaged foods. When reading labels under the term ‘seasonings’, you’ll often find that alliums fall into that category. Always read labels carefully; if you’re unsure about the components, call the manufacturer, and they will let you know. You can, however, avoid foods with unclear labels.

It is also important to note that the FDA doesn’t require manufacturers to list onions as an allergen. However, manufacturers are required to list all ingredients. If the ingredient list doesn’t seem to tell you all you need to know, it is safe to pass it up and only deal with fresh ingredients rather than pre-packaged foods. By doing so, you’ll be taking extra care of your body since you’ll know every ingredient that goes into your meal. It is common to find alliums in foods like:

  • Flavoured cheese.
  • Salsa or Pico de gallo.
  • Flavouring packets.
  • Broths.
  • Frozen or pre-made pizza crust.
  • Frozen entries.
  • Crackers.
  • Premade soups and sauces.
  • Deli meats.
  • Frozen foods.

If you’re generally allergic to alliums, you’ll also have a reaction to flowering amaryllis plants, which are primarily ornamental alliums and various varieties of lilies. Be extra careful when contacting these types of flowers, as they may cause a reaction if you’re extra sensitive.

Onion allergy treatment

When you have an onion allergy, there are various ways you can manage it at home. These include:

  • Epinephrine: This autoinjector is used in treating anaphylaxis that doctors prescribe.
  • Hydrocortisone cream: Topical use can help reduce itching and inflammation.
  • Aloe Vera: If you have itchy hives, aloe vera can help soothe the redness that comes with itching, even though it can’t help histamines level in your blood.
  • Antihistamines: You can find these available as sprayed medications or oral. This medication blocks histamine production, reducing or eliminating minor allergy reactions like nasal congestion, hives, and itching.
  • Albuterol sulphate inhaler: This bronchodilator helps increase airflow through the bronchial tubes.

Even though the above forms of treatment can soothe your immediate symptoms, the best way to treat allergies is by avoiding these trigger foods. In this case, you will need to avoid onions and some alliums, if not all. Even though avoiding these will be hard at first, you will also enjoy a symptom-free life which is better than rushing to the emergency room every time. You can easily enjoy your meals without alliums and onion allergy symptoms.


  1. Arena, A., Cislaghi, C., & Falagiani, P. (2000). Anaphylactic reaction to the ingestion of raw onion. A case report. Allergologia et immunopathologia, 28(5), 287–289.