One-liner#
Evaluate chronic or recurrent rash (>6 weeks) to distinguish common inflammatory conditions (eczema, psoriasis, seborrheic dermatitis) from systemic disease, initiating appropriate topical therapy while knowing when to escalate to systemic treatment or dermatology referral.
Quick nav#
- Red flags / send to ED
- Key history
- Focused exam
- Differential (quick pattern recognition)
- Workup
- Initial management
- Management by diagnosis
- Follow-up
- Patient instructions
- Smartphrase snippets
Red flags / send to ED#
- Erythroderma (>90% BSA involvement) with systemic symptoms
- Rapidly worsening despite treatment with signs of infection
- Blistering involving large areas
- Signs of systemic illness (fever, weight loss, lymphadenopathy) with rash
Urgent (not ED, but expedited workup):
- New rash with joint symptoms → consider psoriatic arthritis, lupus, dermatomyositis
- Photosensitive rash with systemic symptoms → lupus workup
- Rash unresponsive to appropriate treatment for 4-6 weeks
Key history#
Timeline and pattern:
- Duration: weeks, months, years
- Constant vs waxing/waning
- Seasonal variation (worse in winter = eczema; worse in summer = photosensitivity)
- Triggers: stress, foods, weather, products
Location and spread:
- Where did it start? Where is it now?
- Symmetric vs asymmetric
- Flexural (eczema) vs extensor (psoriasis)
- Scalp, nails involved?
Symptoms:
- Pruritus intensity (0-10 scale)
- Pain, burning (suggests different etiology than itch)
- Impact on sleep, quality of life
Prior treatments:
- What has been tried? (OTC, prescription)
- What helped? What didn’t?
- Steroid use history (potency, duration, location)
Associated conditions:
- Atopic history: eczema, asthma, allergic rhinitis, food allergies
- Autoimmune disease
- Joint symptoms (psoriatic arthritis)
- Family history of skin conditions
Exposures:
- Occupation (wet work, chemicals)
- Hobbies
- New products, detergents, fabrics
Focused exam#
- Distribution: flexural vs extensor, symmetric vs asymmetric, sun-exposed vs covered
- Morphology:
- Papules, plaques, patches
- Scale: fine (eczema), silvery thick (psoriasis), greasy yellow (seborrheic)
- Lichenification (thickened skin from chronic scratching)
- Excoriations (suggests pruritus)
- Specific sites:
- Scalp: scale, erythema, hair loss
- Nails: pitting (psoriasis), dystrophy
- Intertriginous areas: maceration, satellite lesions (candida)
- Signs of secondary infection: honey-colored crust, pustules, increased erythema
Differential (quick pattern recognition)#
Common/likely (outpatient)#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Atopic dermatitis (eczema) | “Eczema,” “dry itchy skin,” “had it since childhood” | Atopic history; flexural distribution; chronic relapsing; intense pruritus | Erythematous patches; fine scale; lichenification; flexural | Emollients; topical steroids; trigger avoidance |
| Psoriasis | “Thick scaly patches,” “silvery scales,” “elbows and knees” | Extensor surfaces; scalp/nail involvement; family history; joint pain | Well-demarcated plaques; silvery scale; Auspitz sign; nail pitting | Topical steroids + vitamin D analog; assess for PsA |
| Seborrheic dermatitis | “Dandruff,” “flaky scalp,” “red around nose” | Scalp, nasolabial folds, eyebrows; worse with stress; HIV risk factor | Greasy yellow scale; erythema in seborrheic distribution | Antifungal shampoo; low-potency topical steroid |
| Nummular eczema | “Coin-shaped patches,” “round itchy spots” | Discrete round/oval plaques; very pruritic; often on legs | Well-demarcated round plaques; scale; excoriations | Topical steroids; emollients; rule out tinea (KOH) |
| Lichen simplex chronicus | “Thick itchy patch,” “can’t stop scratching” | Single or few plaques; chronic scratching; often accessible areas | Lichenified plaque; hyperpigmentation; excoriations | Break itch-scratch cycle; potent topical steroid; occlusion |
| Stasis dermatitis | “Itchy legs,” “swelling,” “brown discoloration” | Lower legs; venous insufficiency; edema; older patient | Bilateral medial ankles; hyperpigmentation; varicosities; edema | Compression; emollients; topical steroids; treat venous disease |
| Intertrigo | “Rash in skin folds,” “under breasts,” “groin rash” | Intertriginous areas; obesity; moisture; diabetes | Erythema in skin folds; maceration; satellite papules if candida | Keep dry; barrier cream; antifungal if candida; low-potency steroid |
| Rosacea | “Red face,” “flushing,” “bumps on cheeks” | Central face; flushing triggers (alcohol, heat, spicy food); no comedones | Central facial erythema; telangiectasias; papules/pustules; no comedones | Topical metronidazole or ivermectin; trigger avoidance |
| Tinea versicolor | “Spots on chest/back,” “lighter/darker patches” | Trunk; young adult; hypopigmented or hyperpigmented macules | Fine scale; hypo/hyperpigmented macules on trunk | KOH prep; topical or oral antifungal |
Can’t-miss / urgent#
| Diagnosis | Keywords patients use | Key clues | Focused exam clues | Initial next step |
|---|---|---|---|---|
| Cutaneous T-cell lymphoma (mycosis fungoides) | “Patches that won’t go away,” “been there for years” | Persistent patches/plaques unresponsive to treatment; older adult | Patches → plaques → tumors; “bathing suit” distribution | Derm referral for biopsy; may need multiple biopsies |
| Dermatomyositis | “Rash on eyelids,” “weak,” “muscle pain” | Heliotrope rash; Gottron papules; proximal weakness | Violaceous eyelid erythema; papules over knuckles; proximal weakness | CK, aldolase; ANA; derm/rheum referral; malignancy screening |
| Lupus (cutaneous) | “Butterfly rash,” “sun makes it worse,” “joint pain” | Photosensitivity; malar rash; discoid lesions; systemic symptoms | Malar erythema sparing nasolabial folds; discoid plaques; oral ulcers | ANA, anti-dsDNA, CBC, BMP, UA; rheum referral |
| Psoriatic arthritis | “Joint pain with skin patches,” “sausage fingers” | Psoriasis + inflammatory arthritis; nail changes; dactylitis | Psoriatic plaques; nail pitting/onycholysis; joint swelling | Rheum referral; X-rays of affected joints |
| Drug-induced lupus | “Rash after starting medication,” “joint aches” | Hydralazine, procainamide, isoniazid, minocycline; ANA positive | Malar-like rash; arthralgias; serositis | Stop offending drug; ANA, anti-histone antibodies |
| Paget disease of breast | “Eczema on nipple that won’t heal” | Unilateral nipple/areolar eczematous change; not responding to steroids | Unilateral erythematous, scaly, erosive nipple plaque | Mammogram; derm referral for biopsy |
Workup#
Most chronic rashes are diagnosed clinically. Testing is for atypical presentations or suspected systemic disease.
When to test:
| Test | When to order | Notes |
|---|---|---|
| KOH prep | Suspected tinea (especially nummular-appearing lesions) | Rule out fungal before diagnosing eczema |
| Skin biopsy | Uncertain diagnosis; treatment failure; suspected malignancy | Derm referral usually; punch biopsy 4mm |
| ANA | Photosensitive rash; systemic symptoms; suspected lupus | If positive, add anti-dsDNA, complement, CBC, BMP, UA |
| CBC, CMP | Suspected systemic disease; erythroderma | Rule out underlying malignancy, organ involvement |
| CK, aldolase | Suspected dermatomyositis (rash + weakness) | Elevated in inflammatory myopathy |
| Patch testing | Recurrent contact dermatitis; unclear trigger | Derm/allergy referral |
| HIV test | Severe seborrheic dermatitis; atypical presentation | Seborrheic dermatitis can be first sign of HIV |
When NOT to test:
- Classic atopic dermatitis with atopic history
- Typical psoriasis with family history
- Seborrheic dermatitis in typical distribution
- Clear response to appropriate treatment
Initial management#
- Emollients: Foundation of treatment for all inflammatory dermatoses
- Topical steroids: Mainstay of treatment; match potency to location and severity
- Trigger avoidance: Identify and eliminate exacerbating factors
- Treat secondary infection: If present, treat before escalating anti-inflammatory therapy
Topical steroid potency guide:
| Potency | Examples | Appropriate sites | Duration limit |
|---|---|---|---|
| Low (Class 6-7) | Hydrocortisone 1-2.5% | Face, intertriginous, children | 2-4 weeks |
| Medium (Class 4-5) | Triamcinolone 0.1%, fluocinolone 0.025% | Body, extremities | 2-4 weeks |
| High (Class 2-3) | Fluocinonide 0.05%, betamethasone dipropionate 0.05% | Thick plaques, palms/soles, lichenified areas | 2 weeks |
| Super-high (Class 1) | Clobetasol 0.05% | Thick plaques, palms/soles only | 2 weeks max; not for face/folds |
Management by diagnosis#
Atopic dermatitis (eczema)#
Education:
- Chronic relapsing condition; goal is control, not cure
- Skin barrier dysfunction + immune dysregulation
- Triggers: dry skin, irritants, allergens, stress, infection
- “Soak and seal”: lukewarm bath followed immediately by emollient
Treatment:
Mild-moderate:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Emollients (petrolatum, CeraVe, Vanicream) | Apply liberally after bathing and PRN | None | None | $ | Foundation of treatment; use fragrance-free |
| Hydrocortisone 2.5% cream | Apply BID x 2-4 weeks | Prolonged facial use | Skin atrophy | $ | For face, intertriginous areas |
| Triamcinolone 0.1% cream | Apply BID x 2-4 weeks | Face, skin folds | Skin atrophy | $ | For body; step down to lower potency for maintenance |
| Tacrolimus 0.1% ointment | Apply BID | None significant | Burning initially | $$ | Steroid-sparing; good for face, maintenance; no atrophy risk |
| Pimecrolimus 1% cream | Apply BID | None significant | Burning initially | $$ | Steroid-sparing; less potent than tacrolimus |
Moderate-severe or flare:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Fluocinonide 0.05% cream | Apply BID x 2 weeks | Face, folds | Skin atrophy | $ | For flares; step down after control |
| Clobetasol 0.05% cream | Apply BID x 2 weeks max | Face, folds, large areas | Skin atrophy; HPA suppression | $ | Short-term for severe flares only |
| Prednisone | 40-60 mg x 5-7 days taper | Frequent use; diabetes | Blood glucose | $ | Rescue only; rebound common; avoid if possible |
| Dupilumab | 600 mg loading, then 300 mg Q2W SC | None significant | Conjunctivitis | $$$$ | Derm-initiated; for moderate-severe refractory |
Infection management:
- Dilute bleach baths (¼ cup bleach per full tub) 2x/week for recurrent infections
- If impetiginized: cephalexin 500 mg QID x 7 days or mupirocin 2% TID x 7 days
Follow-up: 4-6 weeks initially; then every 3-6 months for maintenance.
Psoriasis#
Education:
- Chronic immune-mediated disease; not contagious
- Associated with psoriatic arthritis (up to 30%), metabolic syndrome, cardiovascular disease
- Triggers: stress, infections (strep), medications (lithium, beta-blockers), alcohol
- Screen for joint symptoms at every visit
Treatment:
Limited disease (<5% BSA):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Calcipotriene 0.005% cream | Apply BID | Hypercalcemia | Calcium if extensive use | $$ | Vitamin D analog; can combine with steroid |
| Betamethasone dipropionate 0.05% | Apply daily-BID x 2-4 weeks | Face, folds | Skin atrophy | $ | High-potency for thick plaques |
| Calcipotriene/betamethasone (Enstilar, Taclonex) | Apply daily x 4 weeks, then PRN | Face, folds | Skin atrophy; calcium | $$ | Combination more effective than either alone |
| Tazarotene 0.1% cream | Apply QHS | Pregnancy | Irritation | $$ | Retinoid; can combine with steroid to reduce irritation |
Scalp psoriasis:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Clobetasol 0.05% solution/foam | Apply daily x 2-4 weeks | None | None | $ | First-line for scalp |
| Calcipotriene solution | Apply daily | None | None | $$ | Steroid-sparing for scalp |
| Coal tar shampoo | Use 2-3x/week | None | None | $ | Adjunctive; reduces scale |
Moderate-severe (>5% BSA) or refractory:
- Refer to dermatology for phototherapy or systemic therapy
- Systemic options (derm-initiated): methotrexate, apremilast, biologics (TNF inhibitors, IL-17/IL-23 inhibitors)
Screen for psoriatic arthritis:
- Ask about joint pain, stiffness, swelling at every visit
- PEST questionnaire (Psoriasis Epidemiology Screening Tool)
- If positive: rheumatology referral
Follow-up: 4-8 weeks initially; then every 3-6 months.
Seborrheic dermatitis#
Education:
- Chronic condition caused by inflammatory response to Malassezia yeast
- Common locations: scalp, eyebrows, nasolabial folds, ears, chest
- Waxes and wanes; worse with stress, illness, winter
- Not curable but very manageable
Treatment:
Scalp:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Ketoconazole 2% shampoo | Use 2-3x/week; leave on 5 min | None | None | $ | First-line; alternate with regular shampoo |
| Selenium sulfide 2.5% shampoo | Use 2-3x/week | None | None | $ | Alternative antifungal |
| Zinc pyrithione shampoo | Use daily or every other day | None | None | $ | OTC option; maintenance |
| Fluocinolone 0.01% solution | Apply daily PRN for flares | None | None | $ | For inflammation; short-term |
Face/body:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Ketoconazole 2% cream | Apply daily-BID x 2-4 weeks | None | None | $ | First-line for face/body |
| Hydrocortisone 1% cream | Apply BID x 1-2 weeks | Prolonged use | Skin atrophy | $ | For inflammation; short courses |
| Tacrolimus 0.1% ointment | Apply BID | None | Burning | $$ | Steroid-sparing for face; maintenance |
| Pimecrolimus 1% cream | Apply BID | None | Burning | $$ | Steroid-sparing alternative |
Follow-up: 4-6 weeks; then PRN for flares.
Nummular eczema#
Education:
- Coin-shaped (nummular) plaques; very pruritic
- Often on legs; can be triggered by dry skin, contact allergens
- Must rule out tinea (KOH prep) before treating as eczema
- Can be stubborn; may need potent steroids
Treatment:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Triamcinolone 0.1% ointment | Apply BID x 2-4 weeks | Face | Skin atrophy | $ | Ointment better than cream for dry lesions |
| Fluocinonide 0.05% ointment | Apply BID x 2 weeks | Face, folds | Skin atrophy | $ | For thick or refractory plaques |
| Emollients | Apply liberally | None | None | $ | Essential adjunct |
Follow-up: 2-4 weeks; if not responding, reconsider diagnosis (biopsy).
Stasis dermatitis#
Education:
- Caused by chronic venous insufficiency
- Bilateral medial lower legs; associated with edema, varicosities
- Can progress to venous ulcers if untreated
- Compression is the most important treatment
Treatment:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Compression stockings | 20-30 mmHg or 30-40 mmHg | Severe PAD (ABI <0.5) | ABI if PAD suspected | $ | Foundation of treatment; must rule out arterial disease |
| Triamcinolone 0.1% ointment | Apply BID x 2-4 weeks | None | Skin atrophy | $ | For acute inflammation |
| Emollients | Apply liberally | None | None | $ | Prevent dryness and cracking |
Do NOT use:
- High-potency steroids long-term (skin already fragile)
- Neomycin-containing products (high sensitization rate in stasis dermatitis)
Follow-up: 4-6 weeks; vascular surgery referral if severe venous disease or ulceration.
Lichen simplex chronicus#
Education:
- Thickened skin from chronic rubbing/scratching
- Itch-scratch cycle perpetuates the condition
- Common sites: nape of neck, ankles, wrists, vulva/scrotum
- Breaking the cycle is key to treatment
Treatment:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Fluocinonide 0.05% ointment | Apply BID under occlusion x 2-4 weeks | Face, folds | Skin atrophy | $ | Potent steroid needed for thick plaques |
| Clobetasol 0.05% ointment | Apply BID x 2 weeks | Face, folds | Skin atrophy | $ | For very thick plaques |
| Hydroxyzine | 25 mg QHS | Elderly | Sedation | $ | Helps break itch-scratch cycle, especially at night |
Occlusion technique: Apply steroid, cover with plastic wrap or hydrocolloid dressing overnight to enhance penetration.
Follow-up: 2-4 weeks; may need intralesional steroids (derm) if refractory.
Rosacea#
Education:
- Chronic inflammatory condition of central face
- Triggers: sun, heat, alcohol, spicy food, stress, hot beverages
- Subtypes: erythematotelangiectatic (flushing), papulopustular (acne-like), phymatous (rhinophyma), ocular
- Not acne—no comedones; different treatment
- Chronic condition requiring long-term management
Treatment:
Erythematotelangiectatic (flushing/redness):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Brimonidine 0.33% gel | Apply daily | None significant | Rebound erythema | $$ | Alpha-agonist; temporary vasoconstriction; effect lasts 12 hours |
| Oxymetazoline 1% cream | Apply daily | None significant | Rebound erythema | $$ | Alpha-agonist; similar to brimonidine |
Papulopustular (inflammatory):
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Metronidazole 0.75-1% gel/cream | Apply BID | None | None | $ | First-line; anti-inflammatory |
| Ivermectin 1% cream | Apply daily | None | None | $$ | Anti-parasitic (Demodex); once daily dosing |
| Azelaic acid 15% gel | Apply BID | None | None | $$ | Alternative; also helps with hyperpigmentation |
| Doxycycline | 40 mg daily (sub-antimicrobial) or 100 mg daily | Pregnancy | None | $ | For moderate-severe; anti-inflammatory dose preferred |
Avoid: Topical steroids (cause steroid rosacea), harsh products, known triggers
Follow-up: 6-8 weeks; derm referral for refractory cases or laser treatment for telangiectasias.
Tinea versicolor (pityriasis versicolor)#
Education:
- Caused by Malassezia yeast (normal skin flora)
- Common in young adults, warm/humid climates
- Hypo- or hyperpigmented macules on trunk
- Pigment changes may persist months after treatment (not treatment failure)
- High recurrence rate
Treatment:
| Drug | Dose | Contraindications | Monitoring | Cost | Notes |
|---|---|---|---|---|---|
| Ketoconazole 2% shampoo | Apply to affected areas, leave 5-10 min, rinse; daily x 1-2 weeks | None | None | $ | First-line; use as body wash |
| Selenium sulfide 2.5% lotion | Apply to affected areas, leave 10 min, rinse; daily x 1-2 weeks | None | None | $ | Alternative topical |
| Ketoconazole 2% cream | Apply daily x 2-4 weeks | None | None | $ | For limited areas |
| Fluconazole | 300 mg weekly x 2 weeks OR 150 mg weekly x 4 weeks | Liver disease; drug interactions | LFTs if prolonged | $ | For extensive or refractory cases |
| Itraconazole | 200 mg daily x 5-7 days | Liver disease; HF; drug interactions | LFTs | $$ | Alternative oral |
Maintenance: Ketoconazole shampoo weekly to prevent recurrence
Follow-up: 4-6 weeks; counsel that pigment changes resolve slowly over months.
Follow-up#
- Atopic dermatitis: 4-6 weeks initially, then every 3-6 months
- Psoriasis: 4-8 weeks initially; screen for PsA at each visit
- Seborrheic dermatitis: 4-6 weeks, then PRN
- Nummular eczema: 2-4 weeks
- Stasis dermatitis: 4-6 weeks; vascular referral if needed
- Lichen simplex chronicus: 2-4 weeks
Return precautions:
- Rash spreading significantly
- Signs of infection (increased redness, warmth, pus, fever)
- Not improving after 4-6 weeks of appropriate treatment
- New symptoms (joint pain, weakness, systemic symptoms)
- Side effects from treatment (skin thinning, stretch marks)
Patient instructions#
- Moisturize daily, especially after bathing. Use fragrance-free products.
- Take lukewarm (not hot) showers or baths. Hot water dries out skin.
- Apply prescription creams only to affected areas, not all over.
- Use steroid creams for the time prescribed—longer use can thin your skin.
- Avoid scratching. Keep nails short. Try cool compresses for itch.
- Identify and avoid your triggers (certain soaps, fabrics, stress).
- Your condition is chronic—the goal is control, not cure. Flares are normal.
- Call the office if your rash is spreading, looks infected, or isn’t improving with treatment.
Smartphrase snippets#
.ECZEMA
Atopic dermatitis, [mild/moderate/severe]. Distribution: [locations]. No signs of secondary infection. Plan: emollients liberally, [steroid] BID x 2-4 weeks, trigger avoidance. Discussed chronic nature of condition and goal of control. Follow-up in [timeframe].
.PSORIASIS
Psoriasis, [limited/moderate/extensive] disease affecting approximately [X]% BSA. Locations: [sites]. Screened for psoriatic arthritis—[no joint symptoms / joint symptoms present, referring to rheumatology]. Plan: [topical regimen]. Discussed chronic nature, triggers, and associated conditions. Follow-up in [timeframe].
.SEBDERM
Seborrheic dermatitis affecting [scalp/face/body]. Plan: ketoconazole [shampoo/cream] [frequency], [low-potency steroid if needed] for inflammation. Discussed chronic relapsing nature and maintenance therapy. Follow-up PRN for flares.
Related pages#
- Psoriasis (problem) — comprehensive management of chronic plaque psoriasis including systemic therapy options and comorbidity screening
- Atopic Dermatitis (problem) — in-depth management of eczema including flare prevention and steroid-sparing strategies