Skin usually regrows over two to three weeks; however, recovery can take months and most are left with chronic problems. Signs and symptoms
Prodrome
TEN ultimately results in extensive skin involvement with redness, necrosis, and detachment of the top (epidermal) layer of the skin and mucosa. Before these severe findings develop, people often have a flu-like prodrome, with a cough, runny nose, fever, decreased appetite and malaise. A history of drug exposure exists on average 14 days (ranging from 1–4 weeks) prior to the onset of symptoms, but may result as early as 48 hours if it is a reexposure. Skin findings
Initial skin findings include red-purple, dusky, flat spots known as macules that start on the trunk and spread out from there. These skin lesions then transform into large blisters. The affected skin can then become necrotic or sag from the body and peel off in great swaths. Mucosal findings
Nearly all people with TEN have oral, eye and genital involvement as well. Painful crusts and erosions may develop on any mucosal surface. The mouth becomes blistered and eroded, making eating difficult and sometimes necessitating feeding through a nasogastric tube through the nose or a gastric tube directly into the stomach. The eyes can become swollen, crusted, and ulcerated, leading to potential blindness. The most common problem with the eyes is severe conjunctivitis. Complications
Those who survive the acute phase of TEN often develop long-term complications affecting the skin and eyes. Skin manifestations can include scarring, eruptive melanocytic nevi, vulvovaginal stenosis, and dyspareunia.
Loss of the skin leaves patients vulnerable to infections from fungi and bacteria, and can result in sepsis, the leading cause of death in the disease. Death is caused either by infection or by respiratory distress which is either due to pneumonia or damage to the linings of the airway. Microscopic analysis of tissue (especially the degree of dermal mononuclear inflammation and the degree of inflammation in general) can play a role in determining the prognosis of individual cases. Severity score
The "Severity of Illness Score for Toxic Epidermal Necrolysis" (SCORTEN) is a scoring system developed to assess the severity of TEN and predict mortality in patients with acute TEN.One point is given for each of the following factors:
age >40
heart rate >120 beats/minute
carrying diagnosis of cancer
separation of epidermis on more than ten percent of body surface area (BSA) on day 1. Blood Urea Nitrogen >28 mg/dL
Glucose >252 mg/dL (14 mmol/L)
Bicarbonate <20mEq/L

Score
0–1: 3.2% mortality
2: 12.2% mortality
3: 35.3% mortality
4: 58.3% mortality
≥5: 90% mortalityOf note, this scoring system is most valuable when used on the first and third day of hospitalization, and it may underestimate mortality in patients with respiratory symptoms. References
External links

18-203e. at Merck Manual of Diagnosis and Therapy Home Edition
DermNetNZ