Toxic epidermal necrolysis (TEN) is a type of severe skin reaction. Together with Stevens–Johnson syndrome (SJS) it forms a spectrum of disease, with TEN being more severe. Early symptoms include fever and flu-like symptoms. A few days later the skin begins to blister and peel forming painful raw areas. Mucous membranes, such as the mouth, are also typically involved. Complications include dehydration, sepsis, pneumonia, and multiple organ failure.

The most common cause is certain medications such as lamotrigine, carbamazepine, allopurinol, sulfonamide antibiotics, and nevirapine. Other causes can include infections such as Mycoplasma pneumoniae and cytomegalovirus or the cause may remain unknown. Risk factors include HIV/AIDS and systemic lupus erythematosus. Diagnosis is based on a skin biopsy and involvement of more than 30% of the skin. TEN is a type of severe cutaneous adverse reactions (SCARs), together with SJS, a SJS/TEN, and drug reaction with eosinophilia and systemic symptoms. It is called SJS when less than 10% of the skin is involved and an intermediate form with 10 to 30% involvement. Erythema multiforme (EM) is generally considered a separate condition.

Treatment typically takes place in hospital such as in a burn unit or intensive care unit. Efforts include stopping the cause, pain medication, and antihistamines. Antibiotics, intravenous immunoglobulins, and corticosteroids may also be used. Treatments do not typically change the course of the underlying disease. Together with SJS it affects 1 to 2 persons per million per year. It is more common in females than males. Typical onset is over the age of 40. Skin usually regrows over two to three weeks; however, recovery can take months and most are left with chronic problems.