Route Of Exposure

The lime is native to the Indo-Malayan region. It is now grown in tropical regions almost throughout the world, particularly in Florida. There are 2 main types of this small, lemon-shaped green citrus fruit: the acidic (the chief kinds being Persian limes, and Mexican or Key limes), which is grown commercially, and the sweet, which is uncommon in North America. Limes have been crossed with other types of citrus.

Limes are available, if not common, throughout the industrialised world, and have many traditional uses in the developing world. Sweetened or unsweetened bottled lime juice, frozen lime juice, lime syrup and limeade are some of the more popular lime products, and are available in most supermarkets. The lime is used in mixed drinks (such as margaritas), as a marinade, garnish, and sauce, and in the famous Key lime pie. Limes are often made into jam, jelly and marmalade, and they are sometimes pickled. The juice and the skin oil are used for flavouring processed foods. The minced leaves are consumed in certain Javanese dishes. In the Philippines, the chopped peel is made into a sweet with milk and coconut. In tropical Africa, lime twigs are popular chewsticks. Limes are an excellent source of vitamin C.

The juice has been used in the process of dyeing leather, and as an ingredient in cosmetics. The dehydrated peel is fed to cattle. In India, the powdered dried peel and the sludge remaining after clarifying lime juice are employed for cleaning metal. The hand-pressed peel oil is utilised in the perfume industry.

The juice, leaves and root bark are used in a variety of homeopathic applications. In addition, there are many purely superstitious uses for the Lime in Malaya.

Clinical Relevance

Allergen Description

No allergens from this plant have yet been characterised.

Potential Cross Reactivity

Extensive cross-reactivity among the different individual species of the genus Citrus could be expected.

Clinical Experience

IgE-mediated reactions

Lime may induce symptoms of food allergy in sensitised individuals, though this is not common. Allergic reactions are similar to those seen with other citrus fruit,.and consist mainly of contact dermatitis and contact urticaria.

In a study aimed at characterising allergens from raspberry, sera from 8 female patients were assessed. A 25-year-old with periorbital oedema and rhinitis from lemon and other citrus fruits was described, who was prick-to-prick positive to peach, lemon, sweet lime, orange, banana, blueberry, tomato, grape and bell pepper.

An instance has been reported of a bartender with hand dermatitis who developed allergic contact sensitivity to the skin of lemon, lime, and orange, but not to their juices. Although most reported cases of citrus peel allergy are due to d-limonene, in this instance reactions to patch tests for geraniol and citral (2 minor components of citrus peel oil) were positive, whereas those for d-limonene were negative.

Similarly, a 52-year-old woman presented with an eczematous rash at the side of her mouth and lips. She had been sucking the lime from her gin and tonic for up to 1 minute after finishing her drink. Patch tests were positive for geraniol 2%, geranium oil and lime peel. Citrus oil is made up of 90% limonene, and the remaining 10% consists of citral, gerraniol and bergapten.

Other reactions

Non-allergic phytophotodermatitis, a phototoxic reaction occurring in skin exposed to sunlight after contact with plants containing furanocoumarins, has been reported. Ninety-seven (16%) of 622 children and 7 (7%) of 104 counsellors at a camp developed a phototoxic dermatitis. The eruptions were confined to the hands, wrists, and forearms, and appeared as discrete and confluent polymorphous patches and linear streaks. The cause was thought to be the making of pomander balls (sachets). The makers punctured the skin of limes (the principal component) with scissors, releasing oils known to contain photoreactive furocoumarin (psoralen) compounds.

A 6-year-old boy presented with marked, symmetric, painful erythema and oedema of both hands that rapidly developed into dramatic bullae covering the entire dorsum of the hands. The history revealed that the hands had been bathed in lime juice for a prolonged period during the preparation of limeade. This resulted in phytophotodermatitis. The rind contains 6- to 182-fold greater concentrations of all furanocoumarins measured, compared to pulp. Bergapten was the most abundant substance in the rind.

In a group of Thai patients with contact dermatitis, patch-test reactions to extracts of fragrance raw materials, traditionally used in Indonesian cosmetics, were evaluated. Positive reactions to extracts of Citrus aurantifolia Swingle were observed. Specimens taken directly from the citrus fruits (the unconcentrated sources of the fragrance raw materials) were less antigenic.

Sensitisation to pollen from the lime tree may occur.