Introduction: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are infrequent diseases represented by disseminated epidermal necrosis and skin sloughing. They have a representative mortality and morbidity, their early diagnosis and treatment is necessary to provide good results in affected individuals. Objective: to detail the current information related to Stevens-Johnson syndrome and toxic epidermal necrolysis, description, clinical presentation, pathophysiology, diagnosis, differential and treatment. Methodology: a total of 52 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 44 bibliographies were used because the other articles were not relevant for this study. The sources of information were PubMed, Google Scholar,CrossRef, and Cochrane; the terms used to search for information in Spanish, Portuguese, and English were: Stevens-Johnson, toxic epidermal necrolysis, and immunologic burn. Results: Almost all affected individuals present mucosal involvement, with two or more mucosal surfaces involved in up to approximately 80% of the cases. Oral involvement is more frequent, accompanied by mucositis and ulceration in almost all cases. Ocular involvement is also frequent in 60-100% of patients with SJS/TEN, and can present as conjunctival hyperemia and sometimes even complete epidermal detachment of the ocular surface. Gynecologic involvement also varies according to severity, however it is seen in approximately 77% of affected individuals. The precise incidence of genitourinary involvement in individuals affected in the acute phase of SJS/NET is not known. Drugs are the factors most frequently associated with SJS and NET, however, infection, especially Mycoplasma pneumonia, has been implicated. In approximately 15-30% of cases, no causative agent can be identified. Conclusions: SJS-NET are devastating and potentially fatal mucocutaneous diseases. Prior to skin alteration, there is a prodromal phase of symptoms, such as general malaise, fever, pharyngeal pain and cough. Later the skin and mucous membranes are affected, traditionally appearing as erythematous macules or atypical target lesions on the trunk that progress to confluent areas of erythema with dark centers, sheets of denuded epidermis and flaccid blisters presenting positive Nikolskys sign. According to the improvement in early care and the improvement of supportive care the mortality in SJS and NET will continue to decrease. The most important act in the acute phase is immediate withdrawal of the culprit drug when there are signs of SJS-NET, the signs are blisters or erosions that distinguish these can reduce mortality. General supportive care is the mainstay of treatment.