What is the treatment for nummular eczema?

Treatment of Nummular Eczema

High or ultra-high potency topical corticosteroids combined with aggressive emollient therapy form the foundation of nummular eczema treatment, using the least potent preparation that achieves control while avoiding continuous long-term use. 1, 2

First-Line Management

Topical Corticosteroids

• Apply high-potency topical corticosteroids twice daily to coin-shaped lesions until they clear, which typically takes several weeks with proper treatment 1, 2
• Use the least potent preparation that controls the eczema, but nummular eczema often requires higher potency steroids than other eczema types due to the thick, lichenified nature of lesions 1
• Stop corticosteroids for short periods when lesions clear to minimize side effects, particularly pituitary-adrenal suppression in children 1, 3
• Very potent and potent preparations should be used with caution and for limited periods only 4

Essential Skin Barrier Management

• Apply emollients liberally and frequently, especially immediately after bathing, to provide a lipid film that prevents water loss 1
• Replace all soaps and detergents with dispersible cream as a soap substitute, since these products strip natural skin lipids and worsen the inherently dry skin 1
• Regular bathing for cleansing and hydration is beneficial, allowing patients to choose their preferred bath oil and regimen 1

Avoidance Measures

• Eliminate extreme temperatures, hot water baths, and harsh soaps, as these are documented aggravating factors 1, 2
• Avoid wool and other irritant fabrics directly against skin; recommend cotton clothing instead 1
• Keep nails short to minimize scratch-induced damage 1
• Consider screening for and treating dental infections in treatment-resistant cases, as odontogenic infections have been associated with severe, refractory nummular eczema, with 11 of 13 patients showing improvement after dental treatment 5

Second-Line Options

Tar Preparations

• Use 1% ichthammol in zinc ointment for lichenified lesions, as it is less irritant than coal tar and particularly effective for thickened plaques 1
• Coal tar solution at 1% in hydrocortisone ointment is an alternative that does not cause systemic absorption issues unless used extravagantly 1

Antihistamines

• Prescribe sedating antihistamines only for nighttime use during severe pruritic episodes, as their value lies in sedative properties, not direct anti-pruritic effects 1, 3
• Avoid non-sedating antihistamines entirely, as they have no demonstrated value in nummular eczema 1, 3
• Recognize that tachyphylaxis may progressively reduce antihistamine effectiveness 4

Managing Complications

Secondary Bacterial Infection

• Start flucloxacillin immediately if you observe increased crusting, weeping, or pustules, as Staphylococcus aureus is the most common pathogen 1, 3
• Use phenoxymethylpenicillin if β-hemolytic streptococci are isolated 1
• Switch to erythromycin for penicillin-allergic patients or flucloxacillin resistance 1
• Continue topical corticosteroids during bacterial infection when appropriate systemic antibiotics are given concurrently 3

Eczema Herpeticum (Medical Emergency)

• Initiate oral acyclovir immediately if you see grouped vesicles, punched-out erosions, or sudden deterioration with fever 1, 3
• Administer intravenous acyclovir in ill, feverish patients 1, 3

Contact Allergy Evaluation

• Perform patch testing in chronic, recalcitrant cases, as contact allergy is common in nummular eczema, with nickel being the most frequently identified allergen 6, 2

Advanced Therapies for Refractory Disease

Topical Calcineurin Inhibitors

• Consider pimecrolimus cream 1% (Elidel) for adults and children ≥2 years after other prescription medicines have failed 7
• Apply thin layer twice daily only to affected areas, using the smallest amount needed 7
• Do not use continuously for long periods due to uncertain long-term safety and rare reports of cancer (skin or lymphoma), though causality is unproven 7
• Stop when symptoms resolve and use only for short periods with breaks between treatments 7
• Avoid in children under 2 years, patients with weakened immune systems, or those with Netherton's syndrome 7

Biologic Therapy

• Dupilumab demonstrates significant efficacy for nummular-type atopic dermatitis in adults, with substantial reductions in EASI, pruritus VAS, and DLQI scores after 16 weeks, with conjunctivitis being the primary side effect 8

Critical Pitfalls to Avoid

• Do not undertreat due to steroid phobia—explain different potencies and risk-benefit profiles clearly, as patient and parent fears often lead to inadequate treatment 4, 3
• Do not use topical corticosteroids continuously without breaks; implement steroid holidays when lesions clear 1, 3
• Do not delay antibiotics when secondary infection is present, but continue topical steroids alongside systemic antibiotics 3
• Avoid sun lamps, tanning beds, or ultraviolet light therapy during treatment with topical calcineurin inhibitors 7

When to Escalate or Refer

• Failure to respond to high-potency topical corticosteroids after 4-6 weeks 1, 3
• Extensive disease affecting quality of life, particularly in younger patients, office workers, or those with trunk-distributed lesions 6
• Suspected eczema herpeticum requires immediate treatment 3
• Diagnostic uncertainty when annular lesions could represent tinea corporis or other mimics—perform potassium hydroxide examination of skin scrapings 2