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a delayed immunologic type of photosensitivity involving both a chemical substance to which the individual has become previously sensitized and radiant energy.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
References in periodicals archive ?
In childhood group insect bite allergy was seen in 11 patients (25.58%), contact dermatitis in 8 patients (18.60%), atopic eczema in 3 patients (6.97%), seborrheic dermatitis in 5 patients (11.62%), hand and foot eczema in 5 patients (11.62%), sweat retention dermatitis in 3 patients (6.97%), photoallergic dermatitis in 2 patients (4.65%) and others (13.95%) including 2 cases of infective eczematoid dermatitis and one case on each of nummular eczema, discoid eczema, eczematous polymorphic light eruptions and chronic eczema.
Various chemicals in cosmetics (colophony, PPD, balsam peru, cetostearyl alcohol, lanolin, bees wax, formaldehyde, fragrances, musk mix, vanillin, rose oil, triclosan, or other antiseptics) have been implicated to cause primary irritant reactions, allergic contact dermatitis, photoallergic contact dermatitis, contact urticaria, pigment alteration, photosensitivity, brittle hair and nails, and so on (Figure 2).
Photoallergic drug reactions are idiosyncratic cell-mediated hypersensitivity responses, in contrast with phototoxic reactions, which clinically resemble exaggerated sunburn, and are predictable, with severity dependent on the dose of the drug and the extent of exposure to light.
Photoallergic tendencies, xenoestrogen with interference of thyroid function and CNS signaling.
Five earlier safety studies involving a total of 667 patients showed no phototoxicity, contact hypersensitivity, irritation, photoallergic response, or sensitization.
A total of five dermal safety studies showed no phototoxicity, irritation, photoallergic response, sensitization, or contact hypersensitivity.
Photosensitivity reaction may be phototoxic or photoallergic. The phototoxic reaction is based on a non-immunological mechanism and can be provoked in the majority of people on first exposure, if the concentration of substance and the amount of radiation of the appropriate proper wave-lengths are sufficient.
Photoallergic reactions are rare today, except in response to sunscreen ingredients.