Some of the most severe and life-threatening examples of<unk> s are erythema multiforme, Stevens–Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), hypersensitivity vasculitis,<unk>  induced hypersensitivity syndrome (DIHS), erythroderma and acute generalized exanthematous pustulosis (AGEP). These severe cutaneous<unk> s are categorized as hypersensitivity reactions and are immune-mediated. There are four types of hypersensitivity reactions and many<unk> s can induce one or more hypersensitivity reactions. +Hypersensitivity Reactions Reaction Description Mediator Mechanism Clinical phenotype Type I Immediate IgE antigen binds to mast cell/ basophil surface receptors Urticarial, anaphylaxis, angioedema TypeII Antibody-mediated IgM, IgG antibody binds antigen leading to complement-driven cell lysis<unk> -induced thrombocytopenia, hemolytic anemia, Goodpasture's, ANCA vasculitis Type III Immune complex IgM, IgG, IgA antigen-antibody complex deposits in tissues-triggers recruitment of leukocytes Serum sickness, Henoch-Schonlein Purpura Type IV Delayed-type T-lymphocytes Activated T-cells produce cytokines causing inflammation leading to tissue destruction<unk>  reaction with eosinophilia and systemic symptoms (i.e. DRESS syndrome or DIHS), Stevens–Johnson syndrome, toxic epidermal necrolysis, acute generalized exanthematous pustulosis By appearance The most common type of eruption is a morbilliform (resembling measles) or erythematous rash (approximately 90% of cases). Less commonly, the appearance may also be urticarial, papulosquamous, pustular, purpuric, bullous (with blisters) or lichenoid. Angioedema can also be<unk> -induced (most notably, by angiotensin converting enzyme inhibitors). By mechanism The underlying mechanism can be immunological (such as in<unk>  allergies) or non-immunological (for example, in photodermatitis or as a side effect of anticoagulants). A fixed<unk>  is the term for a<unk>  that occurs in the same skin area every time the person is exposed to the<unk> s can occur frequently with a certain<unk>  (for example, with phenytoin), or be very rare (for example, Sweet's syndrome following the administration of colony-stimulating factors). By<unk>  The culprit can be both a prescription<unk>  or an over-the-counter medication. Examples of common<unk> s causing<unk> s are antibiotics and other antimicrobial<unk> s, sulfa<unk> s, nonsteroidal anti-inflammatory<unk> s (NSAIDs), biopharmaceuticals, chemotherapy agents, anticonvulsants and psychotropic<unk> s. Common examples include photodermatitis due to local NSAIDs (such as piroxicam) or due to antibiotics (such as minocycline), fixed<unk>  due to acetaminophen or NSAIDs (Ibuprofen), and the rash following ampicillin in cases of mononucleosis. Certain<unk> s are less likely to cause<unk> s (rates estimated to be ≤3 per 1000 patients exposed). These include: digoxin, aluminum hydroxide, multivitamins, acetaminophen, bisacodyl, aspirin, thiamine, prednisone, atropine, codeine, hydrochlorothiazide, morphine, insulin, warfarin and spironolactone.
Drug eruption
Lichenoid eruption
Streptococcal intertrigo
Polymorphous light eruption
Contact dermatitis
Acneiform eruption
Phototoxic tar dermatitis
Autosensitization dermatitis