Phototoxic reaction is an indirect photosensitive disorder that can be elicited in all persons with sufficient concentration of the photosensitizing agent and exposure to the offending wavelength of light. The immune system does not participatein these reactions. The action spectrum usually includes the UVA range, though certain substances such as porphyrins and a number of dyes photosensitize to visible light. In addition, a very limited number of chemical depend on UVB activation. Phototoxic reaction may be photodynamic or nonphotodynamic in nature, the primary difference being that photodynamic reactions require oxygen. Photodynamic process appears to be responsible for reactions to certain dyes, coal tar, polycyclic hydrocarbons, and porphyrin molecules. Photodynamic reactions induce an excited triplet state which reacts with oxygen, forming a singlet oxygen or superoxide anion. This activated oxygen can then damage cell components. Nonphotodynamic reactions have been described for psoralen photosensitization. In this instance, psoralen compounds intercalate into the DNA helix. On photoactivation with UVA radiation, mono and bifunctional adducts may be formed in the DNA depending on the structure of the psoralen molecule and the wavelength utilized for irradiation. Photoreaction with proteins may also occur.

Clinical featuresThe acute phototoxic reactions are chatarcterized by erythema, edema, and at times blister formation, follwed by hyperpigmentation and desquamation. These reactions are confined to the exposed skin. The clinical reaction may begin from a few minutes to several hours to several days later. There is no incubation period and even the first exposure to light produces symptoms of phototoxic reaction.

DiagnosisThe history and clinical examination supplemented by histopathology and phototest are helpful in diagnosis. Histopathological examination reveals the folowing; (1) epidermal cell degeneration, (2) dilatation of dermal blood vessels, (3) minimal inflammatory cell response in the dermis.

TreatmentPatient should be managed in the similar fashion as a first or second degree burn. Further exposure to the phototoxic agent should be stoped. Topical application of sunscreens is also beneficial.

Unani treatment

• Crush and extract the juice of mint leaves and apply all over the face.
  • Grate a peeled cucumber, add lime juice and blend to make a paste. Apply to the face, let dry and wash off.
  • Mix and stir well to for a lotion two tablespoons vinegar, one tablespoon rosewater, and juice of one cucumber. Dab the face completely, let dry. Repeat the procedure until the lotion has been used up.
  • Grate 2 to 3 peeled carrots, boil in little water until it dries up, cool, and mash. Apply over the face and leave for 10-15 minutes, rub gently before rinsing.
  • peel and mash ripe banana and apply over the face, wash off after ten minutes.
  • Peel and grate raw potato, put into a muslin cloth, tie to form a pad and rub over the face in a firm and circular motion for five minutes then wash the face.
  • Powder dried orange peels and add two tablespoons curd to form a paste.  Apply to the face,  let dry and rinse off with cold water.