Basil is a food which may result in allergy symptoms in sensitised individuals.

Basil Allergy Test: Allergen Exposure

Basil is one of the oldest known herbs used by humans, having been cultivated for thousands of years. It is a member of the mint family and originated in India, although it is now grown worldwide. In India it is a spiritually symbolic plant, and is grown around temples.

It is most commonly used fresh, although it is also available dried. In cookery, basil is usually added towards the end of the cooking process, or as a garnish, as its delicate flavour is easily destroyed by heat. Fresh basil can be preserved by refrigeration or freezing.

Basil is a key ingredient in the Italian pesto, as well as a number of pasta dishes, particularly sauces. It is a popular ingredient in soups and other foods in Chinese cuisine. In Thailand fried chicken is commonly with deep-fried basil leaves.

Basil seeds, once soaked in water, are used as a flavouring in a number of Asian drinks, including faluda and sharbat-e-rihan.

The flower buds are also edible and are used in cooking, having a more subtle flavour than the leaves.

In traditional Chinese medicine, basil is believed to have therapeutic properties including reducing and preventing fevers, relieving stress and tension, improving memory and concentration and improving digestion.

Research has suggested that the essential oil derived from basil may have antifungal and insect-repelling properties.

Basil Allergy Test: Allergen Description

No allergens present in basil have yet been characterised.

Basil Allergy Test: Potential Cross-Reactivity

Extensive cross-reactivity between the different individual species of the genus could be expected, but in fact cross-reactivity does not occur frequently.

Plants belonging to the Lamiaceae family (hyssop, basil, marjoram, mint, sage, lavender, etc.) seem to show cross-reactivity on the basis of clinical history and in vitro and in vivo test results.

Basil Allergy Test: Clinical Experience

Anecdotal evidence suggests that basil may induce symptoms of food allergy in sensitised individuals; however, few studies have been reported to date. It is possible that the allergy occurs more frequently than has been reported.

Two individuals allergic to basil were reported. A 65-year-old woman experienced an episode of dyspnoea, urticaria and angioedema involving the face and lips, which occurred within 30 minutes after eating homemade pesto sauce containing raw basil, pine nuts, garlic, olive oil, and parmesan cheese. She had previously also experienced oral pruritus each time she tasted oregano in a salad, and gave a history of sudden onset of sneezing, nasal congestion, coughing and wheezing every time she smelled lavender.

The second patient, a 25-year-old male, reported the onset of oral pruritus, rhinorrhoea, nasal congestion, pruritus of the eye, lower lip angioedema, and emesis occurring 15 minutes after eating pesto sauce made with the same recipe as described above.

In vitro studies have reported the presence of serum-specific IgE to basil, thyme and oregano in patients sensitised to birch pollen and celery.

Other reactions

Extract of basil can be a skin irritant, and moderately toxic by ingestion.