Common Symptoms
Rash
Most rashes seen in outpatient practice are benign, but a handful are emergencies. The job is to spot petechiae or purpura, mucosal involvement, fever, and rapid progression. This page covers the can't-miss diagnoses (meningococcemia and petechial fever, Stevens-Johnson syndrome / TEN, DRESS, necrotizing fasciitis, toxic shock, anaphylaxis with urticaria, erythema migrans, herpes zoster ophthalmicus), red flags, the minimum safe first-pass workup (full skin and mucous membrane exam, vitals, lymph nodes, photo documentation, targeted POC testing, careful medication history), what can be managed outpatient (atopic dermatitis, contact dermatitis, mild urticaria, tinea, uncomplicated cellulitis, localized zoster), when to escalate to ED, documentation patterns, and return precautions to give every patient. Written for NPs, PAs, and MDs in outpatient practice.
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Common Symptoms
Rash
Why this symptom matters
Most rashes are benign, but a small set are life-threatening and look unimpressive at first. Distribution + morphology + systemic features drive the workup. Always check vitals and mucous membranes.
What must I not miss first?
- Anaphylaxis
- Stevens-Johnson Syndrome / TEN (mucous membrane involvement, drug exposure)
- Meningococcemia (petechiae/purpura + fever)
- Necrotizing soft tissue infection
- Toxic shock syndrome
- Rocky Mountain Spotted Fever (tick exposure, fever, petechiae)
- DRESS (drug reaction with eosinophilia and systemic symptoms)
- Erythema multiforme major
Red flags — escalate or work up urgently
- Mucous membrane involvement (mouth, eyes, genitals)
- Skin pain out of proportion to appearance
- Petechiae or purpura, especially with fever
- Skin sloughing, blisters, Nikolsky sign
- Fever, hypotension, hypoxia, altered mental status
- New medication in past 2-8 weeks (especially antibiotics, anticonvulsants, allopurinol)
- Lymphadenopathy, facial swelling, eosinophilia
- Rapid progression
Minimum safe first-pass workup
- Full vitals + temperature
- Distribution, morphology, mucous membranes, palms/soles, scalp, genitals
- Medication review — onset relative to drug exposure
- Travel, tick exposure, sick contacts, occupational exposures
- Photograph if not sure — track evolution
- CBC + LFTs if drug reaction suspected (DRESS)
- Most uncomplicated rashes need no labs
What can usually be managed outpatient
- Contact dermatitis, eczema flare, urticaria without anaphylaxis
- Tinea, scabies (treat partner/contacts)
- Viral exanthem in well-appearing patient
- Mild drug rash without systemic involvement (still stop the drug)
- Cellulitis with clear margins and normal vitals
When to escalate to ED / higher level of care
- Any anaphylaxis or airway involvement
- Mucous membrane involvement, skin sloughing, or pain out of proportion
- Petechiae/purpura with fever or hemodynamic change
- DRESS, SJS/TEN, or TSS suspicion
- Necrotizing soft tissue infection
What to document when the diagnosis is still uncertain
- Distribution, morphology, mucous membrane status
- Time course relative to medications, exposures, illnesses
- Systemic features — fever, vitals, lymphadenopathy
- Photo if relevant; specific rash differential considered
Safety-net & return precautions to give
- Return or call 911 for trouble breathing, swelling of face/tongue, mouth/eye sores, blistering or peeling skin, fever, or feeling severely unwell.
- Stop suspected medication and call us today if rash spreads quickly or you develop new symptoms.
- Follow up in [X days] for recheck.
Educational guidance for clinicians. Not a substitute for clinical judgment. Always individualize to the patient and your local resources.
Evidence sources
- · AAD Clinical Resources
- · IDSA SSTI Guidelines
Review status
Last reviewed: 2026-04
Reviewed by the MyClinicianGuide editorial team. Cadence: annual.
Educational reference for licensed clinicians (NP, PA, MD, DO). Not a substitute for clinical judgment, institutional protocols, or specialty consultation. Apply in context of the full clinical picture, patient goals, and current standards of care. See About AI guidance for AI-related limitations.
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