IgE-mediated reactions
Anecdotal evidence suggests that Bay leaf may cause symptoms of food allergy in sensitised individuals; however, no studies have been reported to date. A number of reports have described allergic dermatitis resulting from contact with Bay leaf. (1-4) Occupational asthma from inhalation of Bay leaf allergen may occur. (5)
The prevalence of allergy to Bay leaf could be expected to be higher in occupational settings, in particular in the food industry.
An individual with occupational asthma caused by several aromatic herbs –Thyme, Rosemary, Bay Leaf, and Garlic – has been described. The diagnosis was confirmed by several inhalation challenges. (5)
Allergic contact dermatitis from the leaf and the oil has been described. (1, 3) A 55-year-old woman presented with erythema and oedema over her knees, 3 days after the application of laurel oil to relieve joint pain. A patch test to the oil was positive. (4) Allergic contact dermatitis was reported following a massage with a mixture of olive oil and L. nobilis oil. Patch testing was 3+ positive to laurel oil and 2+ to the mixture of olive oil and laurel oil. (6)
A study examined the frequency of dermatologic allergic reactions to the Asteraceae species, using a Compositae mix; 118 of 3 851 (3.1%) individuals tested were positive. Further tests for Laurel oil were positive in 50.5% of cases.(7) Allergic contact dermatitis may be sesquiterpene-lactone-induced. (8)
Other reactions
A number of studies have indicated that Bay leaf may result in physical obstruction, including duodenal obstruction secondary to Bay leaf impaction. (9) Dried Bay leaf was described as an unusual cause of upper gastrointestinal tract haemorrhage,(10) and as an uncommon foreign body in the hypopharynx. (11)
