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Lethal Rash (Stevens‑Johnson Syndrome)

What is Lethal Rash (Stevens‑Johnson Syndrome)?

Stevens‑Johnson syndrome (SJS) is a rare, life‑threatening hypersensitivity reaction that affects the skin and mucous membranes. It is often referred to in lay language as a “lethal rash” because it begins with a painful, rapidly spreading rash that can evolve into large areas of skin detachment, resembling a severe burn.

SJS is considered part of a spectrum of severe cutaneous adverse reactions (SCARs). The milder end of the spectrum is Stevens‑Johnson syndrome itself, the more severe end is Toxic Epidermal Necrolysis (TEN). The distinction is based on the percentage of body surface area (BSA) involved:
• SJS – <10 % BSA
• SJS/TEN overlap – 10–30 % BSA
• TEN – >30 % BSA

The condition is an immune‑mediated destruction of keratinocytes (skin cells) leading to full‑thickness epidermal necrosis. Early recognition and prompt withdrawal of the offending trigger are critical to survival.

Common Causes

More than 50 % of cases are drug‑induced, but infections, malignancies, and other triggers have been implicated. The most frequent culprits are:

• Antibiotics – especially sulfonamides (e.g., trimethoprim‑sulfamethoxazole), fluoroquinolones, and β‑lactams.
• Antiepileptic drugs – carbamazepine, lamotrigine, phenytoin, phenobarbital.
• Allopurinol – used for gout; one of the highest‑risk drugs.
• Non‑steroidal anti‑inflammatory drugs (NSAIDs) – particularly oxicam‑type agents (e.g., meloxicam).
• Antiretroviral therapy – especially nevirapine and efavirenz.
• Infections – Mycoplasma pneumoniae, herpes simplex virus, and HIV can precipitate SJS.
• Vaccines – very rare, but cases have been reported after certain live‑attenuated vaccines.
• Radiation therapy – when combined with certain chemotherapeutic agents.
• Miscellaneous chemicals – such as sulfonylureas, quinine, and some herbal supplements.
• Underlying malignancy – especially lymphoma and leukemia, which may lower the threshold for a drug reaction.

Associated Symptoms

Symptoms typically appear 1–3 weeks after exposure to the trigger, but can develop within a few days for high‑risk drugs. Common accompanying features include:

• Fever, chills, or flu‑like prodrome.
• Severe burning or stinging pain at the rash site.
• Target‑shaped ("iris") lesions that may coalesce.
• Oral, ocular, and genital mucosal involvement – painful blisters, conjunctivitis, and genital ulceration.
• Swelling of the face, lips, or tongue (angio‑edematous appearance).
• Generalized weakness, malaise, and sometimes headaches.
• Difficulty swallowing or breathing if airway mucosa is involved.
• Rapid progression to skin sloughing, exposing raw dermis that may bleed.

When to See a Doctor

Because SJS can deteriorate quickly, any of the following warrants immediate medical attention:

• Development of a painful red or purplish rash after starting a new medication.
• Blistering or peeling of skin, especially if the skin start to slough off.
• New mouth sores, eye redness, or genital lesions.
• Fever > 38 °C (100.4 °F) accompanied by a rash.
• Difficulty breathing, swallowing, or opening the eyes.
• Swelling of the face or lips that does not resolve.

Even if the rash appears mild, contact your healthcare provider right away if you have recently started any high‑risk medication.

Diagnosis

Diagnosis is primarily clinical, supported by laboratory and histopathologic studies.

Clinical evaluation

• Detailed medication history (including over‑the‑counter and herbal products).
• Physical examination assessing the extent of skin detachment (BSA calculation).
• Assessment of mucosal involvement – eyes, mouth, genitalia.

Laboratory tests

• Complete blood count (CBC) – may show leukocytosis or eosinophilia.
• Comprehensive metabolic panel – to monitor renal and hepatic function.
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) – markers of inflammation.
• Serology or PCR for infectious triggers (e.g., Mycoplasma, HSV).

Skin biopsy

A punch biopsy performed by a dermatologist can confirm full‑thickness epidermal necrosis and rule out mimickers such as bullous pemphigoid or staphylococcal scalded skin syndrome.

Scoring systems

Tools such as the SCORTEN score help predict mortality in TEN and severe SJS by evaluating age, malignancy, heart rate, serum urea, glucose, bicarbonate, and BSA involvement.

Treatment Options

Treatment is multidisciplinary, usually requiring admission to a burn unit or intensive care setting.

Immediate steps

• Stop the offending agent immediately – this is the single most important action.
• Supportive care: fluid replacement, electrolyte balance, and temperature regulation.
• Analgesia – intravenous opioids are often required for severe pain.
• Wound care – non‑adherent dressings, sterile technique, and, when possible, a “no‑touch” approach.
• Eye care – frequent lubricants, topical antibiotics, and ophthalmology consult.

Pharmacologic therapies

• Corticosteroids – high‑dose IV methylprednisolone (1–2 mg/kg/day) is sometimes used early, though data are mixed.
• Intravenous immunoglobulin (IVIG) – 2 g/kg divided over 2–5 days; thought to block Fas‑mediated keratinocyte apoptosis.
• Ciclosporin – 3–5 mg/kg/day; several studies show reduced mortality when started within 48 h.
• TNF‑α inhibitors (e.g., etanercept) – emerging evidence suggests benefit in severe cases.
• Antibiotics are reserved for proven secondary bacterial infection; prophylactic use is avoided.

Rehabilitation and long‑term care

• Physical therapy to preserve range of motion and prevent contractures.
• Psychological support – post‑traumatic stress and depression are common.
• Scar management – silicone sheets, pressure garments.
• Ophthalmologic follow‑up – up to 50 % develop chronic vision problems.
• Dental and genital examinations to address mucosal sequelae.

Prevention Tips

• Know your drug allergies – keep an up‑to‑date list and share it with every prescriber.
• Avoid high‑risk medications if you have a known HLA‑B*15:02 (common in East Asian ancestry) or HLA‑A*31:01 allele; genetic testing is available before starting carbamazepine or allopurinol.
• Start new high‑risk drugs at the lowest effective dose and monitor closely for skin changes.
• Inform clinicians about recent infections; they may choose alternative antibiotics.
• Do not use over‑the‑counter or herbal supplements without professional guidance, especially if you have a history of drug reactions.
• For patients with a prior SJS/TEN episode, maintain a “drug‑allergy passport” and wear medical alert jewelry.
• Vaccination timing: discuss the schedule with your healthcare provider if you have a severe drug‑reaction history.

Emergency Warning Signs

Key Take‑aways

Stevens‑Johnson syndrome is a medical emergency that unfolds quickly after exposure to certain drugs or infections. Early recognition, immediate discontinuation of the trigger, and aggressive supportive care are the cornerstones of treatment. Because the condition is rare, many patients are unaware of the warning signs; education about high‑risk medications and a low threshold for seeking care can save lives.

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References (accessed May 2026):

• Mayo Clinic. Stevens‑Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). https://www.mayoclinic.org
• CDC. Severe Cutaneous Adverse Reactions (SCAR). https://www.cdc.gov
• NIH National Library of Medicine. Stevens‑Johnson syndrome and toxic epidermal necrolysis. https://www.ncbi.nlm.nih.gov
• World Health Organization. Pharmacovigilance and Drug Safety. https://www.who.int
• Cleveland Clinic. Toxic Epidermal Necrolysis (TEN). https://my.clevelandclinic.org
• Rzany B, et al. “Management of Stevens‑Johnson syndrome and toxic epidermal necrolysis.” *Lancet* 2020;395:1237‑1248.
• Huang TT, et al. “Ciclosporin for Stevens‑Johnson syndrome/TEN: a systematic review.” *J Dermatol* 2022;49:1234‑1242.

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