Allium Allergy Guide | Allergy Test

Alliums are a core ingredient in most households. Whether it’s dinner or lunch, you’re likely to use alliums in your curry, stir fry, and even salads. Most plants in the allium family are onion-like (to put things into perspective). These plants and species include onions, leeks, garlic, shallots, scallions, and chives. These examples make it easy to recognize because most of them share the same body type. They have grass-like leaves that all emerge from one point on a thickened stem or bulb and fleshy roots from a small area on the lower parts of the plant. These plants can bloom, and their blooms consist of one stalk with an explosion of small flowers at the tip. The allium species aren’t all edible, as some may fall into the category of flowers.

In the United States alone, 400 million pounds of garlic is grown each year (1). From garlic bread to onion rings, it is clear that alliums are the star of most beloved dishes. However, no matter how amazing these plants are in adding flavour to our foods, they can offer a threat to those who suffer from an allium allergy. Within our allium allergy guide, we will discuss symptoms of allergies and intolerances, as well as how to test for the two.


Allium Allergy List

The genus allium consists of 600-920 species, making it hard to list all of these plants. Considering how common alliums are in meals, it is likely that if you have an allergy you will have experienced symptoms by now. For some people, if they have a serious allergy they may experience symptoms after inhaling the smell of an allium or touching it. To name alliums that we encounter daily, they include:

  • Onions.
  • Shallots.
  • Garlic (even wild garlic).
  • Leeks.
  • Chives.
  • Scallions (spring onions).


Onion Allergy

A food allergy often occurs when your immune system mistakes the protein in certain foods for harmful substances such as bacteria or viruses. After this mistake, your immune system releases chemicals such as histamines, causing the typical food allergy symptoms that we often witness.

When suffering from an onion allergy, it’s likely that you’ll be allergic to all types of onions, whether it’s spring onions, wild onions, red onions, or white onions. Cooking down onions doesn’t prevent you from experiencing allergy symptoms, either. An onion allergy can be very tricky to handle, so the main advice to someone suffering from an allergy is to avoid onions in all your meals, whether cooked or raw. When onions are lightly cooked or raw, it increases the chances of experiencing anaphylactic shock, a severe reaction that can result in death if not treated quickly {1}.


How common is onion allergy?

Studies show that onion allergy is uncommon compared to other food allergies and onion intolerance. So, there are very few people suffering from onion allergies. While the chances are low, it doesn’t necessarily mean one can’t suffer from onion allergy. If you’re unsure whether your symptoms are caused by onions or another type of food, you can complete a home allergy test which analyses your sample against the most common allergens. Based on your results from our laboratory, you will be able to rule out 38 popular causes of allergies.


Garlic Allergy

Garlic often adds a pungent and savoury flavour to meals when added. However, a garlic allergy makes it dangerous for these individuals to consume it. Garlic is a very uncommon type of allergy and only affects a small population of people around the globe.


Garlic and onion allergy symptoms

Symptoms of onion allergy and garlic allergy vary from one person to the next. These allium intolerance symptoms can range from mild to severe. They include:

  • Hives or a rash.
  • Nasal congestion.
  • Difficulty breathing.
  • Nausea and vomiting.
  • Tingling or itching in the mouth.
  • Dizziness or lightheadedness.
  • Swelling of the lips, face, tongue, or throat.
  • Stomach pain.
  • Anaphylaxis, although this is rare.

A symptom like anaphylaxis is life-threatening and requires immediate medical attention. These garlic and onion allergy symptoms show within a few minutes to two hours of consumption. You can also find yourself having these allium allergy symptoms if you suffer from mugwort allergy (or other allergies especially ones causing oral allergy symptoms) due to cross-reactivity that happens during pollination season {2}.

Our Allergy 35 Test Kit.

How to treat garlic allergy symptoms

We often consume garlic with other ingredients and foods. For example, when eating garlic bread, there are other ingredients in it, like wheat, gluten, yeast, and others. In such cases, it can be hard to pinpoint the real culprit, and the same happens when you consume soups. However, you can narrow down your search by taking an Allergy Test, which checks through a list of common food allergies and finds a solution by pinpointing the main culprits. If you ever experience anaphylaxis, your doctor will recommend an EpiPen, which you should always carry with you everywhere.


Allium Intolerance

Allium intolerance is an IgG reaction caused by difficulty digesting some foods, and in this case, alliums. When having allium intolerance, it means that you can also have unpleasant physical reactions to them. Some people lack certain enzymes required to digest proteins in some foods. When suffering from allium intolerance, you’ll notice that allium intolerance symptoms will show within a few hours to a few days. That’s because food needs to reach the colon for the symptoms to show up.

Because of how long intolerance symptoms take to show, it is hard to determine which food is causing symptoms because, by then, you’ll have eaten other meals. Allium intolerance often leads to uncomfortable gastrointestinal symptoms. That’s because if your body doesn’t digest these ingredients, they get moved to the colon, where they ferment and form gas. This results in constipation, gas, bloating, stomach ache, and much more. Unlike allium allergy, this isn’t life-threatening but can be pretty uncomfortable.

Another difference between allium allergy and intolerance is where they affect. Allium intolerance often affects the gastrointestinal tract, while allium allergy affects the body’s immune system. And while intolerance symptoms take a while to show, allergy symptoms don’t take long. You’ll also notice that most intolerance symptoms last as long as that food is in your stomach. Once you pass it, the symptoms often disappear. However, in allium allergy, some symptoms can last longer even after your body has rid of that food.


Allium intolerance symptoms

Undiscovered allergies can cause painful stomach issues.

The severity of allium intolerance symptoms varies from one person to the next. You’ll often find that some people experience the symptoms shortly after consuming the food, while others take days to see the symptoms. These symptoms include:

  • Stomach ache.
  • Swelling of tongue, lips, and throat.
  • Itchy mouth or lips.
  • Nasal congestion.
  • Diarrhoea
  • Flatulence.
  • Nausea or vomiting.
  • Rash or hives.


If you suffer from these symptoms and think they could be due to alliums, then it is recommended for you to complete an Intolerance Test. This test kit will help you look for all common food intolerances in your system, including garlic and onions. You will then have a list of foods to avoid. Before taking a test, you could consult your doctor so they look for any underlying conditions that could be causing these symptoms. But if your doctor agrees that they think you have a food intolerance, this test will help you to narrow down which foods are causing your symptoms.


Allium foods to avoid

When suffering from allium allergy or allium intolerance, there are certain foods that you need to avoid. We all know that a lot of meals are prepared using alliums as a base, especially garlic and onions. Because of this, you need to be careful when eating out since foods like curries are full of alliums, so make sure to tell the restaurant staff about your allergy. When food shopping, you also need to look at ingredient lists. For example, buying ready meals or pre-seasoned meat is most likely to contain alliums for flavourings.

Also, check out the ingredients in sauces, seasonings, and soups. Since alliums are great for adding flavour, they are likely to be an ingredient within these foods. When suffering from an allium allergy, ensuring you avoid alliums at all costs should be your goal, mainly because consumption may lead to severe symptoms landing you in the hospital. When suffering from allium intolerance, you could avoid these ingredients as part of an elimination diet. An elimination diet helps you completely cut off that food from your diet. After the recommended amount of time, you’ll reintroduce them and see how much more your system can tolerate that food.

Managing an allium allergy or intolerance can be difficult due to their prevalence in most meals. However, for you to stop experiencing uncomfortable symptoms, it is recommended that you avoid alliums. If you’re unsure whether you are experiencing allergy or intolerance symptoms and would like more advice, please get in touch with our support team who will be happy to help.




  1. Karyn Moyer, 400 Million Pounds of Garlic Grown in U.S. Annually,York%20following%20in%20the%20distance.
  2. 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.
  3. Popescu F-D. (2015). Cross-reactivity between aeroallergens and food allergens. DOI: 10.5662/wjm.v5.i2.31