<prompt> Drug reaction caused by ampicillin: March 2011Exanthematous eruptionFixed drug eruptionLupus erythematosus like rashesPhotosensitivy rashes  <response>: Ans. A: Exanthematous eruption Most severe and life-threatening examples of drug eruptions They are erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, hypersensitivity vasculitis, DRESS syndrome, erythroderma and exanthematous pustulosis. By appearance The most common type of eruption is a morbilliform resembling measles or erythematous rash, but the appearance may also be uicarial, papulosquamous, pustular, purpuric, bullous with blisters or lichenoid. Angioedema can also be drug-induced most notably, by angiotensin conveing enzyme inhibitors. By mechanism The underlying mechanism can be immunological such as in drug allergies or non-immunological for example, in photodermatitis or as a side effect of anticoagulants. A fixed drug eruption is the term for a drug eruption that occurs in the same skin area every time the person is exposed to the drug. Eruptions can occur frequently with a ceain drug for example, with phenytoin, or be very rare for example, Sweets syndrome following the administration of colony-stimulating factors. By drug Examples of common drugs causing drug eruptions are antibiotics and other antimicrobial drugs, sulfa drugs, nonsteroidal anti-inflammatory drugs NSAIDs, biopharmaceuticals, chemotherapy agents, anticonvulsants, and psychotropic drugs. - Common examples include photodermatitis due to local NSAIDs such as piroxicam or due to antibiotics such as minocycline, and the rash following ampicillin in cases of mononucleosis 