Garlic allergy – rare problem or real threat?

Garlic is a plant belonging to the family Liliaceae and the subfamily Aliolidea, which also includes onions, chives or leeks [1]. It is a herb with numerous health-promoting properties, rich in biologically active compounds [5]. This is why garlic has held such an important place in folk medicine for centuries. The active substances it contains have the ability to combat many pathogenic bacteria, e.g. Helicobacter pylori, Mycobacterium, and to stimulate the growth of those with beneficial effects (Lactobacillus) [5]. Garlic exhibits not only antibacterial, but also antifungal and even anticoagulant and anti-atherosclerotic effects. In addition, it increases the body’s defence properties (regulates immune system responses) [5].

Unsurprisingly, the use of garlic and its preparations is a very popular way of self-medication (although not always appropriate) [6]. However, when skin or mucous membranes come into contact with fresh garlic cloves, irritation and even burns can occur [6]. Therefore, it should not be applied externally.

There are also cases of allergy to garlic and even anaphylaxis after garlic consumption [7]. These are mostly described in association with contact dermatitis, occupational asthma and rhinitis [1]. However, immediate allergic reactions after garlic ingestion or contact with this spice are very rare, especially in children [1].

However, a case is known of a 16-month-old boy who experienced extensive urticaria on his face and neck as a result of raw garlic coming into contact with his skin. He had previously eaten garlic in cooked form and this had not caused him any symptoms. He had also never reacted to onions. The child also had other food allergies – to milk and egg white [1]. He underwent skin tests and an oral provocation test. The results were positive. Generalised urticaria occurred 10 minutes after ingestion of raw garlic [1].

The enzyme alliin lyase in garlic has been shown to be responsible for garlic allergy [4]. According to studies conducted so far, it is mainly raw garlic that is allergenic, so people with an allergy can tolerate it in cooked or baked form [7].

After eating garlic, an allergic person may develop:

• urticaria,
• inflammatory skin lesions,
• rhinitis,
• asthma attack,
• angioedema.

An extremely rare anaphylactic episode related to garlic allergy occurred in a patient in China. Within 10 minutes after ingestion of this spice, the man experienced angioedema, dizziness, hypotension and loss of consciousness [7].

Garlic can cross-react with other onion plants. Therefore, there is a risk that people who are allergic to this spice will also show symptoms after consuming onions and leeks (especially in raw form) [4].

If you have a garlic allergy, you also need to be careful with spice blends. It is an ingredient in curries, which, in addition to garlic, also contain turmeric, fenugreek, coriander, nutmeg, coriander, pepper, cloves, Roman cumin, ginger, cinnamon, cardamom and chilli, as well as salt and often monosodium glutamate. Most of these ingredients have allergenic properties. Therefore, it is to be expected that someone who is sensitive to spices will experience an allergic reaction after such a mixture. Even anaphylaxis has been reported after using curry [3].

Aleksandra Lipiec 

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translation: Julia Majsiak