Nummular Eczema

Overview

Nummular eczema is a type of eczema named for its distinctive round, coin-shaped patches ("nummular" means coin-like). The patches are itchy and scaly and may ooze or crust, and they most often appear on the legs, arms, hands, and torso.

The condition tends to be chronic, with patches that flare, fade, and sometimes return in the same spots. It is not contagious. Dry skin is a major contributor, so good skin care is central to management. While there is no permanent cure, most cases respond well to moisturizing, avoiding triggers, and prescription treatments during flares.

Symptoms

The main feature is one or more coin-shaped patches with the following characteristics:

• Round or oval patches, ranging from small to several centimeters across
• Itching, which can be intense, sometimes with burning or stinging
• Patches that may be reddish, pink, or brownish, and that may ooze fluid or form crusts early on
• Dry, scaly, or rough skin as patches mature
• Patches that often appear on the lower legs, forearms, backs of the hands, and trunk

Scratching can worsen the patches and lead to thickened skin or infection. Signs of infection include increasing redness, warmth, swelling, pus, or worsening pain.

Causes

The exact cause is not fully understood, but nummular eczema is strongly associated with very dry skin and a damaged skin barrier that allows irritation and moisture loss. Common contributors and triggers include:

• Dry skin, especially in winter or low-humidity environments
• Minor skin injuries such as scrapes, insect bites, or burns
• Irritants and harsh soaps, frequent hot showers, or wool and rough fabrics
• Contact allergies, including to metals like nickel
• Other skin conditions and certain medications

People with a history of eczema or sensitive skin may be more prone to it.

Risk Factors

• Very dry or sensitive skin
• Living in cold, dry climates or heated indoor air
• A history of eczema or other skin conditions
• Frequent skin injuries or irritation
• Contact with irritants or allergens
• More common in adults, with peaks in middle and older age

Diagnosis

A clinician can usually diagnose nummular eczema by examining the characteristic coin-shaped patches and reviewing symptoms, skin-care habits, and possible triggers. Additional tests are sometimes used to confirm the diagnosis or rule out look-alikes:

• Skin scraping: To rule out a fungal infection such as ringworm, which can look similar.
• Patch testing: To identify contact allergies that may be triggering flares.
• Biopsy: Occasionally done when the diagnosis is uncertain.

Treatment

Treatment focuses on repairing and protecting the skin, easing itching, and calming inflammation.

• Moisturizers: Frequent, generous use of thick, fragrance-free moisturizers, especially right after bathing, is the foundation of care.
• Topical steroids: Prescription corticosteroid creams or ointments to reduce inflammation and itching during flares.
• Gentle skin care: Lukewarm (not hot) showers, mild cleansers, and avoiding harsh soaps and rough fabrics.
• Treating itching and infection: Antihistamines may help with itch, and antibiotics may be needed if patches become infected.
• Other therapies: For stubborn or widespread cases, a dermatologist may recommend light therapy or other prescription treatments.

Prevention

• Moisturize daily, especially after bathing, to keep skin from drying out
• Use lukewarm water and gentle, fragrance-free cleansers
• Use a humidifier in dry indoor air
• Avoid harsh soaps, wool, and known irritants or allergens
• Protect the skin from injury and treat minor wounds promptly
• Avoid scratching, which can worsen patches and lead to infection

When to See a Doctor

See a doctor or dermatologist if you have itchy, coin-shaped patches that do not improve with moisturizing and over-the-counter care, that spread, or that keep returning. Earlier evaluation helps confirm the diagnosis and rule out conditions such as ringworm. Seek prompt care if patches show signs of infection, such as increasing redness, warmth, swelling, pus, or worsening pain, or if you develop a fever.

Related Topics

Frequently Asked Questions

References

1. American Academy of Dermatology Association. Nummular Eczema.
2. MedlinePlus, U.S. National Library of Medicine. Nummular eczema.
3. National Eczema Association. Nummular Eczema.
4. Mayo Clinic. Atopic dermatitis (eczema) — Symptoms and causes.