Phytophotodermatitis

Phytophotodermatitis, also known as berloque dermatitis, margarita photodermatitis, lime disease or lime phytodermatitis is a cutaneous phototoxic inflammatory reaction resulting from contact with a light-sensitizing botanical agent (such as lime juice) followed by exposure to ultraviolet A (UV-A) light (from the sun, for instance). Symptoms include erythema, edema, blisters (vesicles and/or bullae), and delayed hyperpigmentation. Heat and moisture tend to exacerbate the reaction.

A reaction may be elicited in any person who has been exposed to adequate amounts of both a photosensitizer and UV-A light. Phytophotodermatitis is not an immunologic response; no prior exposure to the photosensitizing agent is required.

The photosensitizing substances found in phototoxic plants belong to a class of chemical compounds called the furanocoumarins, which are activated by long-wavelength ultraviolet (UV-A) light. The most toxic of these organic compounds are the linear furanocoumarins, so called since they exhibit a linear chemical structure. Bergapten and xanthotoxin (also known as methoxsalen), two linear furanocoumarins derived from psoralen, are invariably found in plants associated with phytophotodermatitis.