Patch Tests: Skin tests in which the sensitizer is applied to a patch of cotton cloth or gauze held in place for approximately 48-72 hours. It is used for the elicitation of a contact hypersensitivity reaction.Dermatitis, Allergic Contact: A contact dermatitis due to allergic sensitization to various substances. These substances subsequently produce inflammatory reactions in the skin of those who have acquired hypersensitivity to them as a result of prior exposure.Dermatitis, Occupational: A recurrent contact dermatitis caused by substances found in the work place.Perfume: A substance, extract, or preparation for diffusing or imparting an agreeable or attractive smell, especially a fluid containing fragrant natural oils extracted from flowers, woods, etc., or similar synthetic oils. (Random House Unabridged Dictionary, 2d ed)Dermatitis, Atopic: A chronic inflammatory genetically determined disease of the skin marked by increased ability to form reagin (IgE), with increased susceptibility to allergic rhinitis and asthma, and hereditary disposition to a lowered threshold for pruritus. It is manifested by lichenification, excoriation, and crusting, mainly on the flexural surfaces of the elbow and knee. In infants it is known as infantile eczema.Dermatitis, Irritant: A non-allergic contact dermatitis caused by prolonged exposure to irritants and not explained by delayed hypersensitivity mechanisms.Skin Tests: Epicutaneous or intradermal application of a sensitizer for demonstration of either delayed or immediate hypersensitivity. Used in diagnosis of hypersensitivity or as a test for cellular immunity.Allergens: Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Dander: Microscopic particles comprising dead skin, dried salivary proteins, hair, SEBUM and microorganisms, shed by animals which causes allergic reactions in atopic persons.Food Hypersensitivity: Gastrointestinal disturbances, skin eruptions, or shock due to allergic reactions to allergens in food.Drug Hypersensitivity: Immunologically mediated adverse reactions to medicinal substances used legally or illegally.Nickel: A trace element with the atomic symbol Ni, atomic number 28, and atomic weight 58.69. It is a cofactor of the enzyme UREASE.Irritants: Drugs that act locally on cutaneous or mucosal surfaces to produce inflammation; those that cause redness due to hyperemia are rubefacients; those that raise blisters are vesicants and those that penetrate sebaceous glands and cause abscesses are pustulants; tear gases and mustard gases are also irritants.Malassezia: A mitosporic fungal genus that causes a variety of skin disorders. Malassezia furfur (Pityrosporum orbiculare) causes TINEA VERSICOLOR.Flushing: A transient reddening of the face that may be due to fever, certain drugs, exertion, stress, or a disease process.Hand DermatosesScabies: A contagious cutaneous inflammation caused by the bite of the mite SARCOPTES SCABIEI. It is characterized by pruritic papular eruptions and burrows and affects primarily the axillae, elbows, wrists, and genitalia, although it can spread to cover the entire body.Histamine H1 Antagonists, Non-Sedating: A class of non-sedating drugs that bind to but do not activate histamine receptors (DRUG INVERSE AGONISM), thereby blocking the actions of histamine or histamine agonists. These antihistamines represent a heterogenous group of compounds with differing chemical structures, adverse effects, distribution, and metabolism. Compared to the early (first generation) antihistamines, these non-sedating antihistamines have greater receptor specificity, lower penetration of BLOOD-BRAIN BARRIER, and are less likely to cause drowsiness or psychomotor impairment.Skin Irritancy Tests: Tests or bioassays that measure the skin sensitization potential of various chemicals.Dermatitis, Contact: A type of acute or chronic skin reaction in which sensitivity is manifested by reactivity to materials or substances coming in contact with the skin. It may involve allergic or non-allergic mechanisms.Dermatomycoses: Superficial infections of the skin or its appendages by any of various fungi.Loratadine: A second-generation histamine H1 receptor antagonist used in the treatment of allergic rhinitis and urticaria. Unlike most classical antihistamines (HISTAMINE H1 ANTAGONISTS) it lacks central nervous system depressing effects such as drowsiness.Cosmetics: Substances intended to be applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body's structure or functions. Included in this definition are skin creams, lotions, perfumes, lipsticks, fingernail polishes, eye and facial makeup preparations, permanent waves, hair colors, toothpastes, and deodorants, as well as any material intended for use as a component of a cosmetic product. (U.S. Food & Drug Administration Center for Food Safety & Applied Nutrition Office of Cosmetics Fact Sheet (web page) Feb 1995)Erythema Multiforme: A skin and mucous membrane disease characterized by an eruption of macules, papules, nodules, vesicles, and/or bullae with characteristic "bull's-eye" lesions usually occurring on the dorsal aspect of the hands and forearms.Succinic Anhydrides: A subclass of anhydrides with the general structure of dihydrofurandione. They can be substituted on any carbon atom. They modify and inhibit proteins and enzymes and are used in the acylation of amino- and hydroxyl groups.Drug Eruptions: Adverse cutaneous reactions caused by ingestion, parenteral use, or local application of a drug. These may assume various morphologic patterns and produce various types of lesions.Hypersensitivity, Immediate: Hypersensitivity reactions which occur within minutes of exposure to challenging antigen due to the release of histamine which follows the antigen-antibody reaction and causes smooth muscle contraction and increased vascular permeability.Eczema: A pruritic papulovesicular dermatitis occurring as a reaction to many endogenous and exogenous agents (Dorland, 27th ed).Pyroglyphidae: Family of house dust mites, in the superfamily Analgoidea, order Astigmata. They include the genera Dermatophagoides and Euroglyphus.Erythema: Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of causes.Exanthema: Diseases in which skin eruptions or rashes are a prominent manifestation. Classically, six such diseases were described with similar rashes; they were numbered in the order in which they were reported. Only the fourth (Duke's disease), fifth (ERYTHEMA INFECTIOSUM), and sixth (EXANTHEMA SUBITUM) numeric designations survive as occasional synonyms in current terminology.Urticaria: A vascular reaction of the skin characterized by erythema and wheal formation due to localized increase of vascular permeability. The causative mechanism may be allergy, infection, or stress.Immunoglobulin E: An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Antigens, Dermatophagoides: Antigens from the house dust mites (DERMATOPHAGOIDES), mainly D. farinae and D. pteronyssinus. They are proteins, found in mite feces or mite extracts, that can cause ASTHMA and other allergic diseases such as perennial rhinitis (RHINITIS, ALLERGIC, PERENNIAL) and atopic dermatitis (DERMATITIS, ATOPIC). More than 11 groups of Dermatophagoides ALLERGENS have been defined. Group I allergens, such as Der f I and Der p I from the above two species, are among the strongest mite immunogens in humans.