Adverse cutaneous drug reactions are undesirable and typically unanticipated reactions independent of the intended therapeutic purpose of a medication. It may be either immunologic (eg, drug allergy) or non-immunologic. Adverse cutaneous drug reaction produce a wide range of clinical manifestations such as pruritus, maculopapular eruptions, urticaria, angioedema, phototoxic and photo allergic reactions, fixed drug reactions, erythema multiforme,vesiculobullous reactions (eg, Stevens-Johnson syndrome and toxic epidermal necrolysis) and serum sickness .They must be considered in the differential diagnosis of sudden symmetric eruption

Erythema multiforme is an acute immune mediated disorder It is a type IV hypersensitivity reaction leading to dermal vasculitis. Erythema multiforme major usually as a result of medications such as sulphonamides, non-steroidal anti-inflammatories and penicillin and there is skin and mucosal involvement.

Steven-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) are considered a spectrum of acute life-threatening mucocutaneous reactions that differ only in severity. Both diseases are characterized by mucous membrane and skin involvement, are often caused by medications and are collectively known as epidermal necrolysis or scalded skin syndrome.Stevens-Johnson syndrome (SJS) is classified as an epidermal loss <10% of the body surface area.Toxic Epidermal Necrolysis (TEN) is indicated by >30% body surface area erosion. The range of epidermal loss between 10% and 30% is called Stevens-Johnson syndrome-Toxic Epidermal Necrolysis (SJS-TEN) overlap. Severity of illness score [Score of Toxic Epidermal Necrolysis(TEN) ] has been devised to predict prognosis in patients with Epidermal Necrolysis.This scoring system addresses 7 prognostic factors: age, malignancy, heart rate,Body Surface Area involved, serum urea, serum glucose and serum bicarbonate levels.

Interleukin-21 regulates both innate and adaptive immune responses and it is not only has key roles in antitumour and antiviral responses that promote the development of autoimmune diseases and inflammatory disorders. It is recently discovered member of the type 1 cytokine family which is produced by activated clusters of differentiation 4+ T cells ,Natural killer cells and follicular helper T cells.

Inclusion Criteria:

• 20 patients presenting with adverse cutaneous drug reaction (Erythema multiforme, SJS and TEN )
• Patients with definite drug history.
• Both sex will be included.

Exclusion Criteria:

• Patients with a history of topical or systemic treatment (corticosteroids, intralesional steroid injection, immunosuppressive therapy).
• Patients within 4 weeks of the study.
• Patients receiving phototherapy within 6 months of the study.
• Diabetic patients
• Anaemic patients
• Thyroid disorders,
• Chronic liver or Renal diseases
• Atopy and Parathyroid disorders.
• Patients with known autoimmune diseases or cancer.
• Pregnant or lactating womens.