Electrolytes including sodium and potassium and bicarbonate
Fluid shift risk in SJS or TEN
Creatinine and urea
Nephritis support for DRESS
Liver panel
ALT AST elevation support for DRESS hepatitis
CRP as inflammatory marker
Urinalysis
Hematuria or proteinuria support for renal involvement
Additional labs by clinical concern
Venous blood gas for critical illness
pH
lactate mmol per L
Coagulation studies for severe illness or liver dysfunction
CK for myositis or severe systemic symptoms
Troponin and ECG for myocarditis concern in DRESS
Blood cultures for sepsis concern
Etiology and trigger workup
Infectious tests when mimic likely
Respiratory viral testing by local availability
Strep testing when pharyngitis with scarlatiniform rash
HIV testing when risk or severe drug reaction risk stratification
DRESS adjunct tests when available
HHV 6 reactivation testing per local protocols
Hepatitis serologies when hepatitis present
Pitfalls and interpretation
Interpretation limitations
Normal eosinophils do not exclude early DRESS
Fever and leukocytosis can occur in AGEP without infection
Transaminase elevation differential broad in polypharmacy
Diagnostic Tests
Scoring Systems
Clinical scoring use
SCORTEN for SJS or TEN mortality risk
Age threshold factor
Malignancy factor
Heart rate factor
Epidermal detachment percent factor
Urea factor
Glucose factor
Bicarbonate factor
RegiSCAR scoring for DRESS
Fever criterion
Enlarged lymph nodes criterion
Eosinophilia criterion
Atypical lymphocytes criterion
Skin involvement extent criterion
Organ involvement criterion
Resolution time criterion
Alternative cause exclusion criterion
EuroSCAR validation score for AGEP
Pustule morphology criterion
Fever criterion
Clinical course criterion
Neutrophilia criterion
Histology criterion
MRI
MRI use by organ involvement
Brain MRI for neurologic deficits not explained otherwise
Cardiac MRI for myocarditis workup when available
Limitations in unstable patients
CT
CT use by organ involvement
CT chest for pneumonitis concern in DRESS with hypoxemia
CT abdomen for severe hepatitis complications or alternative diagnosis
Contrast avoidance considerations in AKI
Ultrasound
Ultrasound use by organ involvement
RUQ ultrasound for cholestasis or biliary alternate causes
Echocardiography for myocarditis concern or shock
POCUS volume status for extensive skin loss
Dermatologic testing
Skin biopsy and bedside tests
Punch biopsy edge of lesion for suspected SCAR
Interface dermatitis and necrosis support for SJS or TEN
Subcorneal pustules support for AGEP
Direct immunofluorescence when autoimmune blistering in differential
Swabs for HSV when erosions unclear and high suspicion
Disposition
Admit transfer discharge criteria
Admission indications
Suspected SJS or TEN
ICU or burn unit level care triggers in many protocols
Suspected DRESS with organ involvement
AGEP with systemic instability or extensive involvement
Inability to stop culprit drug safely without monitoring
Severe pain requiring parenteral analgesia
Dehydration or poor oral intake
Significant mucosal involvement
Transfer indications
Burn capable center for SJS or TEN
Need for ophthalmology subspecialty care not available locally
Discharge criteria for uncomplicated exanthematous eruption
Stable vitals
No mucosal involvement
No skin pain or blistering
No systemic symptoms
Reliable follow up within 24 to 72 hours
Clear culprit medication discontinuation plan
Follow up planning
Outpatient follow up
Primary care within 48 to 72 hours
Dermatology referral for uncertain diagnosis or prolonged course
Allergy or immunology referral for selected cases
Pharmacy or drug information service consultation for culprit identification
Treatment
General measures by severity
Causative drug management
Stop culprit drug
Class I recommendation based on expert consensus
Avoid cross reactive agents when relevant
Substitute essential therapy with non culprit alternative when possible
Symptom control for uncomplicated exanthem
Topical corticosteroid medium potency
Limited course 7 to 14 days
Oral antihistamine for pruritus
Cetirizine 10 mg PO daily
Loratadine 10 mg PO daily
Hydroxyzine 10 to 25 mg PO q6h PRN pruritus
Emollients and gentle skin care
Avoid NSAIDs if suspected trigger
SJS and TEN supportive care
Level of care
Burn unit or ICU care for significant detachment or systemic instability
ACEP Level C recommendation for early transfer in suspected SJS or TEN based on expert consensus and institutional protocols
Wound and mucosal care
Nonadherent dressings
Temperature controlled environment
Fluid resuscitation individualized to losses
Electrolyte replacement strategy
Pain control multimodal
Nutrition support early
DVT prophylaxis if no contraindication
Ocular care
Early ophthalmology involvement
Lubrication and eyelid hygiene per specialist plan
Infection management
No prophylactic antibiotics routinely
Targeted antibiotics for confirmed infection
SJS and TEN immunomodulating therapies
Systemic therapy selection
Dermatology led selection preferred
Evidence base heterogenous with practice variation
Corticosteroids
Consider early short course in selected cases
Class IIb recommendation based on mixed observational evidence
Cyclosporine
Cyclosporine 3 to 5 mg per kg per day PO or via NG divided BID
Typical duration 7 to 10 days then taper per specialist
Renal function monitoring
Class IIa recommendation in some institutional protocols and reviews
IVIG
IVIG 0.4 g per kg per day for 3 to 5 days in selected cases
Class IIb recommendation due to inconsistent outcome data
TNF alpha inhibitor
Etanercept single dose protocols vary by center
Class IIb recommendation pending broader evidence
DRESS treatment
Core management
Stop culprit drug
Evaluate and manage organ involvement
Systemic corticosteroids for organ involvement
Prednisone 0.5 to 1 mg per kg per day PO for moderate to severe DRESS
Slow taper over weeks to months to reduce relapse risk
Class IIa recommendation based on expert consensus and observational evidence
IV methylprednisolone 1 to 2 mg per kg per day for severe organ involvement
Specialist guided escalation
Steroid sparing and refractory options
Cyclosporine for steroid refractory DRESS in selected cases
IVIG or other immunomodulators per specialist
Monitoring plan
Serial CBC with differential
Serial ALT AST and bilirubin
Serial creatinine and urinalysis
Cardiac monitoring if myocarditis concern
AGEP treatment
Core management
Stop culprit drug
Supportive care
Symptom management
Topical corticosteroids for inflammation
Oral antihistamines for pruritus
Antipyretics avoiding suspected class triggers
Systemic therapy
Systemic corticosteroids reserved for severe or persistent cases per specialist
Class IIb recommendation based on limited evidence
Anaphylaxis and immediate hypersensitivity
Immediate treatment when criteria met
IM epinephrine 0.01 mg per kg up to 0.5 mg adult
Repeat every 5 to 15 minutes if needed
Class I recommendation
Airway support and bronchodilator therapy as needed
IV fluids for hypotension
H1 antihistamine adjunct
Corticosteroid adjunct with delayed onset
Documentation and prevention
Allergy documentation quality
Culprit drug name
Reaction phenotype
Timing from exposure
Severity features
Treatment required
Cross reactivity notes
Special Populations
Pregnancy
Pregnancy considerations
Maternal stabilization priority in suspected SCAR
Medication selection safety review
Prednisone preferred systemic steroid when needed
Avoid teratogenic alternatives when possible
Obstetrics involvement for fetal monitoring if systemic illness
Differential expansion for pregnancy specific dermatoses
Geriatric
Older adult considerations
Polypharmacy and culprit identification complexity
Higher baseline risk for dehydration and AKI in SJS or TEN
Lower physiologic reserve for systemic inflammation
Medication dose adjustment for renal or hepatic dysfunction
Pediatrics
Pediatric considerations
Viral exanthem mimic frequency higher
Weight based dosing for systemic therapies
Lower threshold for ophthalmology in SJS or TEN
Kawasaki disease and MIS C in differential for febrile rash
Background
Epidemiology
Frequency and spectrum
Exanthematous drug eruption most common cutaneous adverse drug reaction
SCAR subset includes SJS TEN DRESS AGEP
DRESS case fatality reported around 10 to 20 percent in reviews
Pathophysiology
Mechanisms
Delayed type hypersensitivity common in morbilliform eruptions
Cytotoxic T cell mediated keratinocyte death in SJS and TEN
Eosinophil and cytokine driven systemic inflammation in DRESS
Neutrophil rich pustular inflammation in AGEP
Viral reactivation associations
HHV 6 reactivation reported in DRESS pathogenesis models
Therapeutic Considerations
Drug withdrawal impact
Early withdrawal associated with improved outcomes in SJS and TEN literature and protocols
Supportive care primacy
Barrier loss drives fluid loss and infection risk in SJS and TEN
Multidisciplinary care central in SJS and TEN protocols
Immunomodulation uncertainty
No universal consensus therapy for SJS and TEN beyond supportive care
Observational evidence supports consideration of cyclosporine in selected cases
Patient Discharge Instructions
copy discharge instructions
Drug eruption discharge instructions
Stop and avoid the suspected medication and related medications as directed
Written list of medications to avoid
Symptom relief plan
Moisturizer multiple times daily
Topical steroid thin layer as prescribed
Oral antihistamine as prescribed for itch
Skin care precautions
Avoid hot showers and harsh soaps
Avoid new cosmetics or topical products until resolved
Follow up plan
Primary care within 48 to 72 hours
Dermatology referral if not improving within 3 to 5 days
Return to ED immediately for red flags
Fever
Facial swelling
Blistering or skin peeling
Mouth sores or eye pain or genital pain
Trouble breathing or wheeze
Dizziness or fainting
Dark urine or yellow eyes
Reduced urine output
Rapid spread of rash
Documentation reminder
Tell every clinician and pharmacist about this drug reaction
References
Clinical guidelines and protocols
Key guidance sources
DermNet NZ morbilliform drug reaction overview and treatment
DermNet NZ drug hypersensitivity syndrome DRESS overview
VUMC burn protocol for SJS and TEN 2025
Emergency Care BC SJS and TEN treatment summary
Evidence based sources
Reviews and criteria
RegiSCAR diagnostic criteria discussion for DRESS
AGEP update and EuroSCAR validation score review
SJS and TEN management review with emphasis on early withdrawal and supportive care
Medscape drug eruptions treatment summary
JACI In Practice 2025 review on diagnosing and managing DRESS
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.