Intolerance Lab

Garlic intolerance and allergy

Garlic can add a great flavour to foods and can even be a star ingredient in some meals (hello, garlic bread!). It is used in most cultures as a staple ‘herb’ or ‘spice’ and is also used therapeutically for its health benefits. Some people take garlic as a supplement for its potential to reduce inflammation, fight off infections, or lower cholesterol and blood pressure. 

However, some people react negatively to eating garlic. If you have an intolerance or allergy to garlic, eating garlic can cause uncomfortable or even life-threatening symptoms. In today’s article, we’ll look at what garlic intolerance and allergy is, what type of symptoms they can cause, which foods you might need to avoid, and how to test for an allergy or intolerance to garlic.

What is a garlic allergy?

Like any allergy, a garlic allergy is an adverse immune reaction. It happens when your body mistakenly thinks that garlic is harmful, and it produces antibodies (special immune cells) to fight it off. The antibodies cause your immune system to release many inflammatory chemicals, like histamine, which trigger allergy symptoms.

Symptoms of garlic allergy

If you have an allergy to garlic, you may experience symptoms like:

  • watery or itchy eyes
  • sneezing
  • an itchy, congested or runny nose
  • skin welts or rashes (like hives)
  • tingling or swelling of the lips, mouth or tongue
  • nausea and vomiting
  • abdominal cramps
  • diarrhoea
  • wheezing or shortness of breath
 

The symptoms of allergy often occur immediately but can take a couple of hours to develop. Immediate medical attention is required if the symptoms are severe and involve difficulty breathing, dizziness, or a loss of consciousness. This type of extreme reaction is called anaphylaxis. 

To have an allergic reaction, you don’t have to eat the garlic. You could have an allergic reaction after inhaling or touching garlic.

 

What is garlic intolerance?

All food intolerances are caused by an issue with digesting, absorbing, or properly eliminating a food. In the case of garlic, it happens when your digestive system can’t process the garlic-like it should. So your body reacts to either the undigested food or a part of the food that the body can’t tolerate. 

Garlic contains specific components that people commonly react to. They are sulphur and fructans. Sulphur is a chemical found in foods, and fructans are a poorly absorbed sugar (known as a FODMAP).

It has been proposed that intolerance to garlic is caused by intolerance to sulphur or FODMAPs. The body struggles to break down the sulphur with sulphur intolerance, so it accumulates and causes symptoms. FODMAPs are a bit different, as they are poorly absorbed sugars that cause digestive issues by drawing water into the intestines and being consumed by gas-producing bacteria. FODMAPs have been identified as a group of foods that can cause symptoms of irritable bowel syndrome (IBS).

Unlike a garlic allergy, intolerance to garlic only happens after you eat garlic. You eat the garlic, and your digestive system reacts. The reaction mainly causes digestive symptoms but can cause symptoms elsewhere in the body.

Symptoms of garlic intolerance

If you have a garlic intolerance, then eating garlic may cause you to experience:

  • bloating
  • burping
  • excessive, frequent or smelly gas
  • stomach aches
  • abdominal cramping
  • nausea and vomiting
  • diarrhoea
  • fatigue
  • brain fog
  • headaches
  • poor sleep
  • garlic body odour
 
Eating even the smallest amount of garlic may cause some people to have excessive body odour. This can occur because garlic intolerance may be caused by too much sulphur accumulating in the body. The smell happens when the sulphur is expelled from the lungs and body.

How common is garlic allergy and intolerance?

Having a true allergy to garlic is rare. If you do have a garlic allergy, it may mean that you need to avoid all forms of garlic, cooked and raw, as well as other foods of the same plant family as garlic.

An intolerance to garlic is much more common. This is because garlic can be poorly digested by people with an intolerance to sulphur and FODMAP foods. If this is the case for you, then you will need to avoid other foods that contain sulphur and FODMAP sugars.

Foods to avoid

Garlic is an interesting plant because it is technically a vegetable that is used as a herb. It is part of the allium family, which includes over 750 flowering plants and vegetables. 

If you are allergic or intolerant to garlic, you may also react to other plants of the same family. This includes:

  • onion
  • shallots
  • leek
  • scallion
  • chives
 

It is common to react to other plants of the same family because they either contain similar plant chemicals (like sulphur) or they have similar proteins as garlic. If you have an intolerance to sulphur, you will react to other foods that contain sulphur – this will include foods outside of the allium family. If you have an allergy to garlic, your immune system may recognise the proteins in other plants as if they are garlic. It will react to them in the same way as it does garlic.

When avoiding foods containing garlic and the allium family, it’s essential to be vigilant about the foods you buy or order at restaurants. Garlic is often used as a base in dishes and many packaged foods, including canned soups, pasta, frozen or pre-prepared meals, salad dressings, sauces, and snacks. When eating out, be sure to tell the staff that you’re allergic or intolerant to garlic.

How to test for a garlic allergy or intolerance

To test for a garlic allergy, you can have a blood test or a skin prick test. To do these, your doctor may give you a referral to an allergist.

To test for garlic intolerance, you can complete our intolerance test. Simply order your test online, and send a sample of your hair to our lab. The test covers over 350 foods that you may be intolerant to. This is a simple way to determine what food, or group of foods, maybe causing your reaction.

Summary

Today we’ve had an in-depth look at garlic allergy and intolerance. We learnt that a garlic allergy is an immune reaction to garlic. In contrast, garlic intolerance is caused by an issue with digesting garlic. We then looked at what symptoms you might expect if you have a garlic allergy or intolerance. After reviewing the garlic plant family, known as the allium family, we learnt about the other foods you might react to if you have a garlic allergy or intolerance. Finally, we explored what testing you can do to diagnose a garlic allergy, as well as the simple test we offer for food intolerances.

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