Urgent Care · Common Complaints
Rash
Most rashes seen in urgent care 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, Stevens-Johnson syndrome / TEN, DRESS, necrotizing fasciitis, toxic shock, anaphylaxis with urticaria, erythema migrans, herpes zoster ophthalmicus), red flags, minimum safe first-pass workup (full skin and mucous membrane exam, vitals, lymph nodes, photo documentation, targeted POC testing), what can be managed outpatient (atopic dermatitis, contact dermatitis, mild urticaria, tinea, uncomplicated cellulitis), when to call ED, documentation patterns, and return precautions to give every patient. Written for NPs, PAs, and MDs in outpatient practice.
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Urgent Care · Common Complaints
Rash
Why this symptom matters
Most rashes are benign. A handful are emergencies. Look for petechiae/purpura, mucosal involvement, fever, and rapid progression.
What must I not miss first?
- Meningococcemia / petechial fever
- SJS / TEN
- DRESS
- Necrotizing fasciitis
- Toxic shock syndrome
- Anaphylaxis with urticaria
- Erythema migrans (Lyme)
- Herpes zoster ophthalmicus
Red flags — escalate or work up urgently
- Petechiae or purpura — especially with fever
- Mucosal involvement (eyes, mouth, genitals)
- Skin pain out of proportion, crepitus, bullae, dusky skin
- Fever, hypotension, AMS
- Rapidly spreading erythema
- Recent new medication (Bactrim, allopurinol, anticonvulsants)
- Eye involvement, especially with vesicles on tip of nose (Hutchinson's sign)
Immediate Management — While You Work It Up
- Epinephrine 0.3 mg IM — give immediately if urticaria plus any systemic symptom including throat tightness, hypotension, stridor, or vomiting. Anaphylaxis until proven otherwise. Do not wait.
- Diphenhydramine 25–50 mg IV or IM — for allergic or urticarial rash.
- Remove the offending agent — if drug reaction suspected, stop the medication and document.
- Draw and photograph cellulitis borders — measure and document spreading erythema. Draw margins in pen to track progression.
- IV access — if petechiae, purpura, fever, or any systemic symptoms are present.
- Do not discharge petechiae with fever — this is meningococcemia until proven otherwise. Call 911.
Minimum safe first-pass workup
- What to ask: onset, distribution, evolution, fever, pain/itch, new medications, exposures, sick contacts, immunizations, sexual history, tick exposure
- What to examine: full skin exam (including mucous membranes, palms, soles, scalp), vitals, lymph nodes
- Photo for chart documentation if possible
- POC glucose if AMS
- Strep, mono, COVID testing as appropriate
What can usually be managed outpatient
- Atopic dermatitis flare, contact dermatitis, mild urticaria without airway symptoms
- Tinea, intertrigo, candidiasis
- Uncomplicated cellulitis with drawn margins and 24-hour follow-up
- Localized herpes zoster in immunocompetent patient (early antiviral)
- Insect bites without systemic symptoms
When to escalate to ED / higher level of care
- Petechial/purpuric rash with fever — meningococcemia until proven otherwise
- Mucosal involvement or skin sloughing — SJS/TEN
- Eye involvement in zoster, especially Hutchinson's sign
- Necrotizing infection clues
- Anaphylaxis (give IM epi first)
- Toxic appearance, sepsis criteria
- Suspected DRESS with eosinophilia, organ involvement
What to document when the diagnosis is still uncertain
- Distribution, morphology, mucosal involvement, photo if possible
- Vitals, mental status, recent medications
- "Petechial fever / SJS-TEN / DRESS / nec fasc / TSS / anaphylaxis considered because… ruled out because…"
- Treatment, response, return precautions, follow-up
Safety-net & return precautions to give
- Return or call 911 for fever with rash, blistering or skin peeling, mouth or eye involvement, severe pain, rapid spreading, blue lips, trouble breathing, or face/lip swelling.
- Stop any new medication suspected as the cause; bring the bottle to follow-up.
- Follow up with PCP or dermatology in 24–72 hours.
Geriatric-specific modifiers (apply on top of the above)
The guidance above applies to all adult patients seen in this setting. Layer the points below for adults 55+, geriatric (65+), and frail younger adults — they are additions, not replacements.
In adults 55+, geriatric (65+), and frail younger adults, skin is thinner, immune response is blunted, and presentations are atypical — even "mild" rashes can deteriorate quickly and may be the first sign of infection, sepsis, drug reaction, vasculitis, or pressure injury.
- Herpes zoster: dermatomal pain may precede the rash by days; start antivirals within 72 hours of vesicle onset to reduce post-herpetic neuralgia. Always check for ophthalmic involvement (V1 distribution, Hutchinson's sign).
- Drug eruptions: common culprits in older adults include allopurinol, antibiotics (especially Bactrim), anticonvulsants, and ACE inhibitors. Always review medications added in the past 1–6 weeks.
- Cellulitis: draw and date the borders; older adults often lack fever or leukocytosis. DVT can mimic cellulitis — assess for unilateral calf swelling.
- Pressure injury: examine sacrum, heels, hips, and any pressure point in immobile or recently hospitalized patients. Stage and document offloading plan.
- Scabies outbreaks are common in long-term care — itching at night, web spaces, wrists; treat patient and close contacts simultaneously.
- Use Beers-aware antihistamines: avoid diphenhydramine when possible (sedation, anticholinergic, falls); prefer second-generation agents (cetirizine, loratadine).
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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