Contact Pigmentation and Dermatitis
Contact Pigmentation and Dermatitis is well known that certain chemicals, if present in the skin of an individual, can enhance the sensitivity of the skin towards sunlight. These agents are called ‘photosensitisers’. Substances which act as photosensitisers include perfumes, hair oils,and some other components present in some plants and drugs. Oils are commonly used by a large number of individuals for regular application to the hair or skin.
Some individuals however, develop photosensitivity to the oil,and thereafter if the patient exposes that area of the skin to sunlight after having applied the oil, that area is likelyto develop pigmentation, or even, dermatitis. Such pigmentation usually manifests in the form of blotches on the skin of the face, especially the cheeks and the forehead, if the oil was applied to the face. Sometimes however, if the pigmentation is due to application of the oil to the hair, the pigmentation tends to occur along the hair-line on the forehead, sides of the face, the external ears and the neck. Oil in the hair may also produce pigmentation on the upper back in women who wear low-cut outfits.
Perfumes are also commonly used by a large number of people but some individuals can develop photosensitivity to the perfume, leading to pigmentation in the region where the perfume was applied. A perfume applied as a spray generally produces a conglomeration of minute pigmented spots localised to the area exposed to the perfume. Sometimes a perfume applied by another individual may also be responsible for the pigmentation if the two persons had been sitting
together.
Some plants also produce certain components which have the potential to produce photosensitisatibn. The best example of a plant containing a photosensitiser component is the plant called babchi(Psoralea corylifolia)used for the treatment of vitiligo. The chemical present in this plant is called psoralen. Several varieties of this chemical are present in several other plants also. Some of the psoralen-containing plants are wild weeds, some are used as salads, and others are available as fruits.
Common fruits like the lemons, oranges and figs, and parsley and parsnip are well known to contain psoralens but the content of psoralen is usually very low. Therefore, these fruits and salad leaves do not produce any harmful effect. Sometimes however, when they are used in excessive quantities, especially as a herbal medicine or if the content of psoralen in the plant is high, it can lead to pigmentation.
The pigmentation produced by a photosensitiser isusually very intense and dark and therefore, it takes several months or a year or so to disappear.
The best way to avoid photosensitivity is to avoid unnecessary use of oils,perfumes and herbal products. Oils as a rule have no useful purpose for the hair or the skin and it is preferable to apply perfumes on the clothes rather than on the skin. The herbal products are best avoided.
Sometimes photosensitivity is caused by oral ingestion of a food or certain photosensitising drugs. It is therefore, necessary to avoid undue exposures to sunlight, especially when consuming a photosensitiser drug. The drugs known to produce photosensitive reactions include sulphonamides, Ledermycin, Griseofulvin and Psoralen.
Filed under: Skin Disorders