What is the treatment for nummular eczema?

Treatment of Nummular Eczema

Topical corticosteroids are the mainstay of treatment for nummular eczema, using the least potent preparation required to control symptoms, combined with aggressive skin hydration and avoidance of irritants. 1

First-Line Treatment Approach

Topical Corticosteroids

• Start with moderate to high-potency topical corticosteroids applied twice daily to affected areas, as potent corticosteroids are significantly more effective than mild-potency agents for moderate to severe eczema (70% vs 39% treatment success). 2
• Apply triamcinolone acetonide 0.1% cream or equivalent moderate-to-potent corticosteroid 2-3 times daily to coin-shaped lesions, rubbing in gently. 3
• Once daily application is equally effective as twice daily for potent corticosteroids, so you can simplify to once daily if adherence is an issue. 2
• Do not apply corticosteroids more than twice daily, as increased frequency does not improve outcomes. 1
• Stop corticosteroids for short periods when possible to minimize side effects, particularly skin atrophy. 1

Essential Skin Care Measures

• Eliminate all soaps and detergents that strip natural skin lipids; substitute with dispersible cream as a soap alternative. 1
• Apply emollients liberally and regularly after bathing to create a surface lipid film that prevents evaporative water loss. 1
• Encourage regular bathing for both cleansing and hydration, allowing patients to select their preferred bath oil and bathing regimen. 1
• Avoid extreme temperatures and irritant clothing such as wool; recommend cotton clothing instead. 1
• Keep nails short to minimize scratching damage. 1

Second-Line Treatment Options

Tar Preparations and Alternatives

• Use ichthammol 1% in zinc ointment for lichenified (thickened) eczema, as it is less irritant than coal tar preparations. 1
• Coal tar solution 1% in hydrocortisone ointment is generally preferred over crude coal tar when tar therapy is indicated. 1
• These preparations do not cause systemic side effects unless used extravagantly. 1

Antihistamines for Severe Pruritus

• Prescribe sedating antihistamines (diphenhydramine, clemastine) only at nighttime during severe pruritic episodes, as they work through sedation rather than direct anti-pruritic effects. 1
• Avoid daytime use of sedating antihistamines. 1
• Do not prescribe non-sedating antihistamines, as they have little to no value in treating nummular eczema. 1

Managing Secondary Infections

• Treat overt secondary bacterial infection with flucloxacillin for Staphylococcus aureus, phenoxymethylpenicillin for β-hemolytic streptococci, or erythromycin for penicillin allergy. 1
• Watch for increased crusting, weeping, or pustules as signs of bacterial superinfection. 4
• If you observe grouped vesicles, punched-out erosions, or sudden deterioration with fever, suspect eczema herpeticum and initiate oral acyclovir immediately, as this is a medical emergency. 1, 4

Advanced Treatment Strategies

Occlusive Dressing Technique

• For recalcitrant lesions, apply triamcinolone acetonide cream, cover with pliable nonporous film, and seal edges for 12-hour occlusion (typically overnight). 3
• Additional moisture can be provided by covering the lesion with a dampened clean cotton cloth before applying the nonporous film. 3
• Apply additional cream without occlusion during the day. 3
• Discontinue occlusive dressings immediately if infection develops and institute appropriate antimicrobial therapy. 3

Proactive (Weekend) Maintenance Therapy

• After achieving remission, apply topical corticosteroids twice weekly (weekend therapy) to previously affected areas to prevent relapse, which reduces flare-ups from 58% to 25%. 2
• This proactive approach is significantly more effective than reactive treatment (applying only when flares occur). 2

Special Populations and Safety Considerations

Children

• Use topical corticosteroids cautiously in children due to risk of pituitary-adrenal axis suppression. 1
• Systemic corticosteroids have a limited role and should only be considered after exhausting all other treatments. 1

Areas at Risk for Atrophy

• Avoid very potent corticosteroids on thin-skinned areas and implement "steroid holidays" when possible. 4
• The frequency of abnormal skin thinning is low overall (1% across trials) but increases with higher-potency agents. 2

When to Refer

Refer to dermatology if:

• Treatment failure after 4 weeks of moderate-potency topical corticosteroids. 4
• Extensive disease requiring systemic therapy or phototherapy. 1, 4
• Diagnostic uncertainty exists. 1

Emerging Therapies

• Dupilumab (IL-4/IL-13 receptor antagonist) shows significant improvement in EASI, pruritus VAS, and DLQI scores for nummular-like atopic dermatitis phenotype in adults, with conjunctivitis being the primary side effect. 5

Common Pitfalls to Avoid

• Do not use non-sedating antihistamines, as they are ineffective for nummular eczema. 1
• Avoid hot water baths and harsh soaps, which are common aggravating factors. 6, 7
• Do not overlook emotional stress and alcohol consumption as disease triggers. 6
• Patch testing should be considered for chronic, recalcitrant cases, as contact allergy (particularly nickel) is common. 6, 7