# Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

> Stevens-Johnson syndrome and toxic epidermal necrolysis for NEET-PG Paediatrics covering drug triggers, BSA classification, Nikolsky sign and supportive care.

- Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/stevens-johnson-syndrome-and-toxic-epidermal-necrolysis
- Exam / course: NEET-PG · Subject: Paediatrics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Fitzpatrick's Dermatology; Nelson Textbook of Pediatrics
- How to cite: "Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/stevens-johnson-syndrome-and-toxic-epidermal-necrolysis

## Direct answer

Stevens-Johnson syndrome and toxic epidermal necrolysis are severe cutaneous adverse reactions with widespread epidermal necrosis and detachment, most often triggered by a drug and occasionally by infection. They lie on one spectrum separated by the percentage of body surface area detached, so withdrawing the culprit drug at once and treating the child in a burn-capable unit are the two actions that matter most.

## What you must remember

- **Definition:** SJS and TEN are mucocutaneous reactions with epidermal necrosis and detachment; TEN is the more extensive form.
- **BSA classification:** SJS involves below 10 per cent detachment, the overlap 10 to 30 per cent, and TEN above 30 per cent.
- **Common culprits:** sulphonamides including cotrimoxazole, aromatic anticonvulsants such as phenytoin, carbamazepine and lamotrigine, allopurinol, nevirapine and oxicam NSAIDs.
- **Pharmacogenomics:** HLA-B\*15:02 is linked with carbamazepine reactions in people of Asian ancestry, and HLA-B\*58:01 with allopurinol.
- **Nikolsky sign:** lateral pressure that slides the epidermis confirms epidermal separation and signals evolving TEN.
- **Infective triggers:** Mycoplasma pneumoniae and herpes simplex infection can cause SJS, so the drug history alone is not enough.
- **Severity score:** SCORTEN, calculated within the first 24 hours and again on day 3, predicts mortality and guides the intensity of care; it was derived in adults, so use it cautiously in children.

## Managing a child with suspected SJS-TEN, stepwise

A four-year-old on cotrimoxazole for a urinary infection develops fever, painful red eyes and sore lips on day ten. Two days later, flaccid blisters form on the trunk and the skin peels on light rubbing.

1. **Stop the culprit:** Withdraw the suspected drug at once, since continued exposure keeps the reaction active.
2. **Measure the detachment:** Estimate the percentage of body surface area involved with a Lund-Browder chart, which is preferred in children.
3. **Check the Nikolsky sign:** Gentle lateral pressure that moves the epidermis supports evolving TEN.
4. **Transfer for burn care:** Admit to a unit with burn or dermatology expertise, with a warm, humidified room and adequate pain control.
5. **Protect the mucosa:** Urgent ophthalmology review for conjunctival and corneal involvement, careful oral care and checks for genital and anal erosions.
6. **Dress the skin:** Use non-adherent dressings, avoid adhesive tape and friction, and watch closely for sepsis and fluid loss.
7. **Decide on adjuncts:** Systemic corticosteroids and intravenous immunoglobulin remain debated, so they are used only within expert protocols.

## Where the exam tries to catch you

Errors here usually come from delayed withdrawal of the drug and from mislabelled severity.

- **Trap:** continuing the drug while waiting for the diagnosis. — **Correct:** withdrawal is the first and most important step, because ongoing exposure sustains the reaction.
- **Trap:** using the adult Rule of Nines to estimate detachment in a child. — **Correct:** Lund-Browder charts account for the changing proportions of head and limbs in children and are preferred.
- **Trap:** calling the lesions erythema multiforme because targets are present. — **Correct:** mucosal erosions, atypical targets and skin detachment place the reaction within the SJS-TEN spectrum.

## Frequently asked questions

### What is the first step in managing Stevens-Johnson syndrome in a child?

Stop the suspected culprit drug immediately, because continued exposure keeps the epidermal injury active. Then transfer the child to a unit with burn or dermatology expertise for fluid, skin, eye and mucosal care.

### How is SJS distinguished from TEN?

Stevens-Johnson syndrome involves less than 10 per cent of body surface area with epidermal detachment, overlap involves 10 to 30 per cent, and TEN involves more than 30 per cent. The percentage is estimated carefully, using a Lund-Browder chart in children.

### What does a positive Nikolsky sign mean?

A positive Nikolsky sign means gentle lateral pressure slides the epidermis over the dermis, indicating epidermal separation. It supports SJS or TEN, although it can also occur in pemphigus, so the clinical context still matters.

### Which HLA allele should be checked before carbamazepine in people of Asian ancestry?

HLA-B\*15:02 testing is recommended before starting carbamazepine in people of Asian ancestry, according to pharmacogenomic guidance. A positive result prompts the choice of an alternative anticonvulsant.