Atopic Dermatitis (AD) vs Allergic Contact Dermatitis (ACD): Stepwise Management, Prescription Pearls, and Clinical Algorithms

Atopic Dermatitis (AD) vs Allergic Contact Dermatitis (ACD)

(Natural history → severity classification → stage-directed topical and systemic treatment ladders → RDU prescription examples & high-yield pearls)

1 Pathophysiology Snapshot

Key element	Atopic Dermatitis (AD)	Allergic Contact Dermatitis (ACD)
Immune bias	Th2-skewed (IL-4, IL-13, ± IL-31)	Type IV delayed T-cell hypersensitivity (Th1 → IFN-γ)
Barrier integrity	Congenitally leaky (↓ filaggrin → ↑ TEWL)	Intact until allergen re-exposure
Recurrence driver	Endogenous barrier defect ⇒ chronic relapsing course	Continued / intermittent allergen contact

2 Severity & Stage Classification

2.1 Atopic Dermatitis

Clinical score	Mild	Moderate	Severe
SCORAD	< 25	25–50	> 50
EASI	< 7	7–21	> 21

Morphologic stages: Acute flare (erythema, vesicle, ooze) → Sub-acute (papule, crust) → Chronic (lichenification, fissure).

2.2 Allergic Contact Dermatitis

Stage	Morphology	Typical duration
Acute	Vesicle, weep, edema	1–14 days
Sub-acute	Crust, scale, scattered papules	2–6 weeks
Chronic / Lichenified	Thick plaque, fissure, dyspigmentation	> 6 weeks / repeated flares

Overall severity: % BSA involved and functional impact (e.g., occupational hand eczema).

3 Step-Up Topical Drug Ladder

3.1 Atopic Dermatitis (2023 AAD / AAAAI)

Step	When to use	Core prescriptions (RDU format)
0 Foundation	Every patient	• Emollient (petrolatum/ceramide) liberal ≥ BID • Trigger avoidance
1 Mild / maintenance	SCORAD < 25, localised	Hydrocortisone 1 % cream thin BID topical × 7 days
2 Moderate flare	SCORAD 25–50 or face/flexures	Triamcinolone 0.1 % ointment BID × 10 d ＋ Tacrolimus 0.03 % ointment BID up to 6 wk
3 Severe chronic / frequent flare	SCORAD > 50, ≥10 % BSA, ≥4 disturbed-sleep nights/wk	Clobetasol 0.05 % cream BID × 7 d → taper ＋ NB-UVB phototherapy
4 Systemic conventional	Failure / intolerance step 3	Cyclosporine 3 mg/kg/d PO BID × 12–16 wk / Methotrexate 15 mg PO weekly + folate
5 Targeted systemic	Refractory or steroid-sparing	Dupilumab 600 mg SC load → 300 mg SC q2 wk / Tralokinumab 300 mg SC q2 wk / Upadacitinib 15–30 mg PO qd

Pruritus control: Hydroxyzine 25 mg PO hs (child 0.5–1 mg/kg).

3.2 Allergic Contact Dermatitis – Evidence-Based Ladder

Stage / Severity	Drug approach	Example (RDU)
Acute, localised (<10 % BSA)	Medium-potency TCS	Betamethasone valerate 0.1 % cream BID topical × 10 d
Acute, widespread / facial edema	① Burow wet compress ② High-potency TCS ③ Short oral steroid if > 20 % BSA or peri-orbital	Prednisone 0.75 mg/kg/d PO × 5 d → taper 10 mg q2 d (total 14 d)
Sub-acute / Chronic lichenified	Potent TCS under occlusion ± TCI eyelid; nightly sedating antihistamine	Clobetasol 0.05 % ointment BID × 7 d on / weekend pulse
Severe hand / refractory	Systemic immunomodulator	Alitretinoin 30 mg PO qd (6 mo) or Azathioprine 2 mg/kg/d PO
Maintenance / Prevention	All patients	Patch-test-guided allergen avoidance ＋ Barrier cream / gloves ＋ Emollient after wash

4 When & How to Introduce Oral Therapy

Indication (either disease)	First-line oral agent	Key adult regimen	Safety points
Severe itch impacting sleep	Hydroxyzine	25–50 mg PO hs (max 100 mg/d)	Sedation; avoid alcohol, driving; ECG elderly
Acute severe flare (> 10 % BSA)	Prednisone	0.5–1 mg/kg/d PO × 5–7 d → taper same length	Limit courses (<2/yr); check BP, glucose
Chronic moderate-severe AD	Cyclosporine	3–5 mg/kg/d PO divided BID (≤ 6 mo)	BP, creatinine q2 wk → monthly
Steroid-sparing long-term AD	Methotrexate	15–25 mg PO weekly + folate	CBC, LFT q4–8 wk
Refractory AD	Dupilumab	600 mg SC load → 300 mg q2 wk	Conjunctivitis (10 %); no routine labs
Chronic hand-ACD unresponsive	Alitretinoin	30 mg PO qd × 24 wk	Teratogenic; monitor lipids, LFT

Always combine with proactive topical weekends + daily emollient.

5 Integrated Escalation Algorithm (Adult)

For ACD, allergen identification & elimination supersedes every pharmacologic step.

6 Unified RDU Prescription Templates

Prednisone (30 mg)

1 tab × 1 PO qd for 7 days, then taper by 10 mg every 2 days (total 14 days).

Clobetasol 0.05 % ointment

apply thin BID topical to plaques for 7 days, then once daily 7 days.

Tacrolimus 0.03 % ointment

apply BID topical to face/flexures starting day 8 for 6 weeks.

Hydroxyzine 25 mg

1 tab PO hs prn itch (max 100 mg/d).

Cyclosporine 100 mg caps

3 mg/kg/day PO divided BID; titrate to trough 100–150 ng/mL; planned 16-week course.

Dupilumab 300 mg/2 mL

600 mg SC loading, then 300 mg SC q2 wk until week 16 review.

7 High-Yield Examination Pearls

Barrier repair + trigger control remain first-line for both conditions.
Topical steroid potency = site × stage (low face, high lichenified limbs).
Hydroxyzine is night-time only; switch to non-sedating agents for daytime.
Patch testing is obligatory in ACD; without allergen eviction, relapse is inevitable.
Short oral corticosteroids (≤ 2 weeks) are rescue only; chronic use is a red-flag answer.
Cyclosporine is still first systemic option for chronic severe AD when biologics unavailable.
Dupilumab/JAK inhibitors now precede broad immunosuppressants in updated AD guidelines.
Always screen TB, hepatitis, HIV before starting systemic immunosuppression.
Document EASI/SCORAD before & after therapy—quality-of-care metric often examined.
In any algorithm, identify & avoid allergen sits at the root for ACD; pharmacotherapy is only a bridge.

Quick Reference Cheat-Sheet

Step	AD Core Drug	ACD Core Drug	Monitoring
Mild	Hydrocortisone	Betamethasone valerate	—
Mod	Triamcinolone ± Tacrolimus	Clobetasol pulses	Skin atrophy caution
Severe	Clobetasol + NB-UVB	Prednisone burst	Phototherapy schedule / glucose
Steroid-sparing	Cyclosporine / MTX	Alitretinoin / AZA	BP, CBC, LFT
Targeted	Dupilumab / JAKi	— (off-label)	Lipids, TB screen

Use this synthesized guide for bedside decisions, OSCE stations, and prescription writing with confidence.