Reactions by the Sun
Photosensitivity reactions are those important clinical and produced abnormal, triggered or aggravated by exposure to light, usually sunlight. Unlike fototoxia, skin overreacts and does not play only an increase of tonality, but appear eczema lesions, blistering, etc …
Fototóxia
It is the increased absorption of sunlight by making contact or drugs or chemicals, or sometimes by alterations in the metabolism of persons or in certain diseases. The injuries that occur are the same as sun exposure produces only more intense and appear less exposure time.
1. Fototoxia induced by drugs.
It is a cutaneous adverse reaction due to systemic or topical exposure of a drug and light. The chemicals may be responsible, in addition to drugs, cosmetics and industrial products. The reaction can occur in any individual, is required and dose-dependent, and essentially it is an exaggerated sunburn. It is more common than photoallergic reactions and may also occur at any age and any skin type. Eczematous reaction is not seen in phototoxic reactions. Reactions by the Sun
The drugs involved are:
nalidixic acid, amiodarone, captopril, chlorothiazide, etretinate, phenothiazines (chlorpromazine, promethazine, thioridazine, etc..), furosemide, griseofulvin, naproxen, pyrazinamide, piroxicam, psoralens or furocoumarins, sulfonamides, tetracyclines (especially doxycycline and dimetilclortetraciclina), and derivatives tar.
By eliminating the offending drug, the lesions subside.
2. Drug-induced photosensitivity.
The drug present in the skin absorbs light (especially UV) and forms a photoproduct that binds to proteins to form a complete antigen, which causes the allergic reaction. The lesions of eczema, itchy blisters and oozing deaparición in areas exposed to sunlight, even if exposure persists extieden throughout the body. Photoallergy may persist for months or years despite the absence of contact with the substance responsible.
* Causing general administration:
or Phenothiazines
or Sulfonamides
or group
* The administration of topical:
* halogenated Salicylanilides (deodorants and soaps)
* PABA and derivatives (sunscreens)
* Cinnamates and benzophenones (sunscreens)
* Benzocaine
* neomycin
* Musk Perfume
* thiourea present in the neoprene
For diagnostic tests are used and fotopatch patch test, which is the reproduction of the application, a small portion of the product suspect in the skin for 24 hours and exposure to a UVA lamp to different spectra to reproduce the lesion of eczema.
Allergy Photosensitive by plants (Phytophotodermatitis)
It is a contact dermatitis caused by plants and exposure to sunlight. There is a phototoxic or photoallergic reaction, caused by photosensitizing substances (furocoumarins), present in various plants.
* Plants producing phytophotodermatitis
or Rutaceae: Lima, orange, bitter orange, lemon, bergamot, common rue.
or Umbelliferae: parsley, chervil, celery, parsnips, fennel, dill, carrots,
or Compositae: Yarrow, Yarrow and Chamomile
or Cruciferae: Mustard
or Moraceae: Higueras (only leaf and stem)
or Ranunculaceae: Buttercup
or Rosaceae: Agrimonia
or Legumes: Peas
or hyperactive: St. John’s Wort
It can occur at any age and race. The professions most affected include gardening, horticulture, floriculture, agriculture, etc. It is more common in summer. In the acute phase appears erythema, vesicles and blisters with itching, but no eczema.
There may be a residual pigmentation artificial shapes (lines, etc., Depending on some outside work). The lesions were distributed in areas of contact, especially in the arms and legs. The acute eruption spontaneously yields, but hyperpigmentation may persist for weeks.
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