f283 Oregano

f283 Oregano Scientific Information

Type:

Whole Allergen

Display Name:

Oregano

Route of Exposure:

Ingestion

Family:

Lamiaceae

Species:

Origanum vulgare

Latin Name:

Origanum vulgare

Other Names:

Spanish thyme, Wild marjoram

Summary

Oregano is a perennial aromatic plant frequently used as seasoning in Mediterranean countries, particularly in Turkish, Greek and Italian cooking. Food allergic reactions caused oregano are very rare, with occurrences being limited to single case reports. Symptoms of oregano allergy include pruritus, swelling of the lips and tongue and upper respiratory difficulty. Contact reactions to oregano are also possible in sensitized individuals.

Allergen

Nature

Oregano is a perennial aromatic plant belonging to the Lamiaceae family, which also contains basil, marjoram, mint, sage and lavender (1, 2). Oregano has been cultivated in the Mediterranean area for hundreds of years and now can be found worldwide. It is frequently used as culinary seasoning due to its distinctive taste, especially in Turkey, Greece and Italy. Oregano leaves and oil have been used for medicinal purposes in many cultures, where they believed to have antibiotic and antioxidant properties (3, 4).

Taxonomy

Taxonomic tree of Olive (5)
Domain	Eukaryota
Kingdom	Plantae
Phylum	Tracheophyta
Subphylum	Spermatophytina
Class	Magnoliopsida
Family	Lamiaceae
Genus	Origanum

Epidemiology

Worldwide distribution

Allergic reactions caused by ingestion of oregano are very rare, with occurrences being limited to single case reports (2).

Route of Exposure

Main

Ingestion (2).

Clinical Relevance

Oregano allergy caused by ingestion has been reported in a 45-year-old male patient. He had previous history of IgE-dependent rhinitis and asthma. Within a few minutes of ingesting pizza containing oregano, the patient exhibited pruritus, swelling of the lips and tongue, dysphagia, dysphonia, progressive upper respiratory difficulty, and intense facial and palpebral edema. The symptoms abated after receiving epinephrine, corticosteroids, antihistamines and fluid therapy in an emergency care unit. Skin prick testing for was positive for oregano and thyme, as well as other members of the Lamiaceae family, reactions were negative in 10 control subjects. The patient subsequently experienced allergic reactions to food containing thyme alone. The patient had detectable specific IgE levels to oregano, thyme, marjoram and basil, the control subjects were negative (2).

Atopic Dermatitis

In a study of 55 patients with suspected contact dermatitis, skin patch testing with a group of spices was performed, with the most common reactions being to ginger (12.7%), nutmeg (9.1%), and oregano (7.3%) (6).

Molecular Aspects

Allergenic molecules

The following allergens have been characterized from Origanum vulgare leaves (Allergome 2021):

Allergen	Type	Mass (kDa)
Ori v	Unknown function	-

Allergens present in oregano have not been well characterized (2).

Cross-reactivity

Although reports are limited, cross-sensitivity between oregano and other plants of the Lamiaceae family (e.g. thyme, marjoram and basil) has been suggested (2).

Compiled By

Author: RubyDuke Communications

Reviewer: Dr. Christian Fischer

Last reviewed:April 2022

References

Basavand E, Babaeizad V, Mirhosseini HA, Dehghan Niri M. Occurrence of leaf spot disease caused by Phoma herbarum on oregano in Iran. Journal of Plant Pathology. 2020;102(2):575-6.
Benito M, Jorro G, Morales C, Peláez A, Fernández A. Labiatae Allergy: Systemic Reactions Due to Ingestion of Oregano and Thyme. Annals of Allergy, Asthma & Immunology. 1996;76(5):416-8.
Singletary K. Oregano: Overview of the Literature on Health Benefits. Nutrition Today. 2010;45:129-38.
Neill C, Nelssen J, Tokach M, Goodband R, Derouchey JM, Dritz S, et al. Effects of oregano oil on growth performance of nursery pigs. Journal of Swine Health and Production. 2006;14.
ITIS. Origanum vulgare 2021 [cited 2021 18.01.22]. Available from: https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=32632#null.
Futrell JM, Rietschel RL. Spice allergy evaluated by results of patch tests. Cutis. 1993;52(5):288-90.