Treatment of Nummular Eczema
Apply moderate-to-potent topical corticosteroids once or twice daily to the coin-shaped lesions as first-line therapy, combined with aggressive emollient use, as nummular eczema lesions are typically thick and lichenified, requiring higher potency preparations than mild eczema. 1
First-Line Topical Corticosteroid Strategy
Use moderate-to-potent topical corticosteroids (such as mometasone furoate 0.1% or clobetasol propionate 0.05%) applied once or twice daily directly to the nummular plaques, as these thick, lichenified lesions require higher potency preparations to penetrate effectively 1, 2, 3
Potent topical corticosteroids are significantly more effective than mild-potency preparations, with 70% versus 39% achieving treatment success (OR 3.71,95% CI 2.04 to 6.72) 2
Once-daily application of potent topical corticosteroids is equally effective as twice-daily application (OR 0.97,95% CI 0.68 to 1.38), so once daily may be sufficient for most patients 2
Use the least potent preparation that controls the disease, and implement "steroid holidays" (short breaks) when possible to minimize side effects 4, 1
Very potent and potent corticosteroids should be used with caution for limited periods only 4, 1
Essential Emollient Therapy
Apply emollients liberally at least 2-4 times daily, immediately after bathing (within 3 minutes of patting skin dry), as two-thirds of nummular eczema patients have co-existing skin dryness 1, 5
Use ointments or thick creams rather than lotions, as the thick, lichenified plaques characteristic of nummular eczema require maximum occlusion and penetration 1
Urea-containing emollients (10-20%) are particularly effective for the hyperkeratotic, scaly plaques typical of nummular eczema 1
Continue aggressive emollient use even when lesions appear controlled, as this is the cornerstone of maintenance therapy 1, 6
Use soap-free cleansers exclusively and avoid hot water, as soaps and detergents remove natural skin lipids and worsen the underlying dry skin 4, 1, 7
Limit bathing to 10-15 minutes with lukewarm water only to prevent excessive drying 1
Adjunctive Tar Preparations for Lichenified Lesions
Consider ichthammol 1% in zinc ointment or coal tar solution 1% for thick, lichenified nummular plaques, as these can be particularly useful for healing chronic lesions 4, 1
Ichthammol paste bandages can be especially effective for lichenified eczema typical of nummular lesions 4, 1
Managing Pruritus
Prescribe sedating antihistamines (such as diphenhydramine or hydroxyzine) exclusively at nighttime for severe itching, as their benefit comes from sedation rather than direct anti-pruritic effects 4, 1, 6
Non-sedating antihistamines have no value in eczema and should not be used 4, 1, 6
Large doses of antihistamines may be required in children 4
Identifying and Treating Secondary Infection
Watch for increased crusting, weeping, or pustules, which indicate secondary bacterial infection with Staphylococcus aureus - this is common in nummular eczema 4, 1, 6
Add oral flucloxacillin as first-line antibiotic while continuing topical corticosteroids 4, 1, 6
Use erythromycin when there is resistance to flucloxacillin or in patients with penicillin allergy 4
Do not delay or withhold topical corticosteroids when infection is present - they remain the primary treatment when appropriate systemic antibiotics are given concurrently 1, 6
Proactive Maintenance Therapy to Prevent Relapse
After achieving clearance, apply topical corticosteroids twice weekly (weekend therapy) to previously affected sites to prevent relapse, as nummular eczema has a chronic and relapsing course 1, 2, 5, 7
Weekend (proactive) therapy results in a large decrease in likelihood of relapse from 58% to 25% (RR 0.43,95% CI 0.32 to 0.57) 2
Addressing Aggravating Factors
Counsel patients to avoid emotional stress and alcohol consumption, as these aggravate nummular eczema 5
Keep nails short to minimize excoriation from scratching 4
Avoid irritant clothing such as wool next to the skin; cotton clothing is more comfortable and recommended 4
Consider patch testing in patients with chronic, recalcitrant nummular eczema, as contact allergy is common (nickel is the most common allergen identified) 5, 7
Second-Line Phototherapy
For treatment-resistant cases, consider narrow band ultraviolet B (312 nm) phototherapy, which has shown effectiveness in chronic atopic eczema 4, 1
Narrow band UVB was shown to be superior to low-dose broadband UVA or visible light placebo in adults with moderate to severe atopic eczema 4
Advanced Systemic Therapy for Severe, Refractory Disease
For severe, refractory nummular eczema phenotype of atopic dermatitis, dupilumab (a monoclonal antibody against IL-4 and IL-13 receptors) has shown significant improvement in EASI scores, pruritus VAS, and DLQI scores after 16 weeks of treatment 8
Systemic corticosteroids have a limited but definite role only for tiding occasional patients through acute severe flares after exhausting all other options - they should never be used for maintenance treatment 4, 1, 6
Common Pitfalls to Avoid
Do not undertreat due to steroid phobia - explain the different potencies and the benefits/risks clearly to patients, as lack of adherence often traces back to patients' fears of steroids 4
Do not use topical corticosteroids continuously without breaks - implement "steroid holidays" when possible 4, 1
Short-term use (median 3 weeks) of topical corticosteroids shows no evidence for increased skin thinning, though longer-term use (6-60 months) does show increased risk 2, 3