Oregano is a herb which may result in allergy symptoms in sensitised individuals.

Oregano Allergy Test: Allergen Exposure

Oregano is particularly similar in appearance to marjoram, to the point that the two species are often confused for one another. This is compounded by the fact that historically classifications often confused the two. Today, both are placed in the genus Origanum, and marjoram is considered to be a type of oregano.

French marjoram, or hardy marjoram is a cross between marjoram and oregano, and shares many of the same properties or marjoram but with increased resistance to cold.

Oregano has a stronger flavour and scent than marjoram, and is commonly included in herb mixtures, or bouquets garni. The leaves can often be more flavourful when dried than fresh.

Oregano is also a member of the same family as mint, basil and sage. Originating in the Mediterranean region of Europe and Asia, it has been cultivated since ancient times for both culinary and medicinal purposes. Today it is an important element of Mexican, Greek, North African and Spanish cooking.

In Turkish cuisine, oregano is widely used for flavoring meat, including mutton and lamb, and is readily available as a condiment in kebab restaurants.

Within Mediterranean cuisine, oregano is used to add flavour to a number of different foods and dishes, including tomato sauces, eggplant, seafood, pork, lamb, chicken, soups, fried vegetables, barbeque sauce, egg and cheese dishes, and stuffings. It is a key ingredient in traditional Greek salad.

It gives a characteristic taste to pizza, and many pasta dishes, and is the herb most associated with Italian cooking.

Oil of Oregano is used in perfume making. Medicinal uses include pain relief and the treatment of digestive complaints.

Oregano Allergy Test: Allergen Description

No allergens present in oregano have been characterised to date.

Oregano Allergy Test: Potential Cross-Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, in particular between oregano and marjoram.

Oregano Allergy Test: Clinical Experience

Oregano may uncommonly induce symptoms of food allergy in sensitised individuals.

In one case a 45-year-old man experienced three reactions to food: as a result of oregano on a single occasion, and twice to thyme. He had pruritis and swelling of the lips and tongue, dysphagia, dysphonia, and progressive upper respiratory difficulty, as well as intense facial and palpebral oedema.

On two occasions he also had hypotension, vomiting, and nausea. The onset was within minutes after the ingestion of pizza containing the herb in the first instance, meat seasoned with thyme in the second, and snails with thyme in the third.

In another case a 45-year-old female patient with facial eczema that appeared 20 minutes after ingestion of oregano and was exacerbated by sun exposure was reported. A patch test was positive. Three other patients were reported to be positive to oregano on a patch test, but their symptoms were not described.