Nummular Eczema: Causes, 7 Types Dermatologists See, How to Tell It From Ringworm, Creams, Pills and Why It Keeps Coming Back
Nummular eczema (also called nummular dermatitis) is an inflammatory skin condition in which well-defined, round or oval patches about the size of a coin, 1–10 centimetres across, appear on the skin. They itch intensely and tend to come and go over a long period. These patches are not a fungal infection and do not spread from person to person. They are most common on the shins, arms, backs of the hands and trunk.
Most people see a doctor because they thought it was ringworm, then spent several weeks applying antifungal cream or mixed creams on their own with no improvement. Some find the patches getting thicker and spreading. This article divides nummular eczema into the 7 types dermatologists see most often, explains how to tell it from ringworm and psoriasis, and lists the medicines doctors actually use, their strengths, how long they take to work, and why the rash tends to return.
What does nummular eczema look like?
Nummular eczema has typical features that help a doctor tell it apart from other conditions just by looking.
Shape: round or oval with a clear edge and the same colour throughout, without the clearing in the centre seen in ringworm.
Size: mostly 1–4 centimetres, though some patches grow to 10 centimetres.
Number: usually several patches, spread over both sides of the body, from 1–2 patches up to dozens.
Surface: at first small red bumps or tiny blisters that merge, sometimes weeping fluid. Later the patch becomes dry, scaly and thickened from scratching.
Symptoms: intense itching, sometimes burning, worse at night and after a hot shower.
Common locations: shins and lower legs, tops of the feet, arms, backs of the hands and trunk. It is uncommon on the face and scalp.
What causes nummular eczema?
The exact mechanism is not known, but dermatologists see several clear contributing factors, and each patient often has more than one.
Dry skin (xerosis): the most common factor, which is why flare-ups happen in cool weather, in dry air, and in people who sit in air-conditioned rooms all day.
Hot showers and harsh soap: these strip the natural oils from the skin and damage its protective barrier.
Skin injury: scrapes, insect bites and chemical burns. Some people's patches start exactly where they once had a wound.
Bacteria on the skin: Staphylococcus aureus is often found on nummular patches and makes them inflamed and weepy.
Contact allergy: for example to nickel, chromate, fragrance, and creams containing neomycin. In some studies about 1 in 3 patients had a positive contact allergy test.
Poor circulation in the legs: in older adults with varicose veins or swollen legs, patches on the shins heal slowly.
Certain medicines: nummular eczema has been reported after isotretinoin, interferon and TNF inhibitors.
Allergic disease: in children and teenagers, nummular eczema often occurs together with atopic dermatitis.
Nummular eczema can occur at any age, but it is most common in two groups: men aged 50–70 and women from their teens to early working years.
Is nummular eczema contagious?
No. Nummular eczema is inflammation of the skin itself, not an infection that spreads to others. Sharing towels or a bed does not cause the rash in people at home. The only exception is a rash with a bacterial infection that has formed honey-coloured yellow crusts. During that time, keep towels separate until the infection has been treated.
Quick 5-point check: is your rash nummular eczema?
The rash is round or oval with a clear edge and an even red colour, not clearing in the centre.
There are several patches, on both sides, for example both the left and right shins.
It itches intensely, especially at night or after bathing.
The skin around the patches is dry, or it appears in cool, dry weather.
You have used antifungal cream for 2–4 weeks and the rash has not cleared.
If 3 or more apply, nummular eczema is likely, but a doctor still needs to confirm it, because ringworm, psoriasis and some skin conditions that need a biopsy can look similar.
Type 1: acute, with blisters and weeping
Appearance: small red bumps 1–2 millimetres across and clear blisters grouped in a circle. The skin is wet and weeping, then dries into a crust.
Cause: intense early inflammation, usually following very dry skin, a scrape or an insect bite.
Severity/urgency: moderate. The itching can prevent sleep, and scratching risks a secondary bacterial infection.
When to see a doctor: weeping for more than 2–3 days, a rapidly spreading rash, or yellow crusts appearing. See a doctor within 1 week.
At this stage doctors usually advise a wet compress with saline or clean water for 10–15 minutes, 2–3 times a day, before applying a steroid cream so that the skin dries faster.
Type 2: chronic, with thick, dry, scaly patches
Appearance: raised, thick patches that are dark red or brown with dry scaly skin. Some become so thick that the skin lines are very visible (lichenification).
Cause: a rash that has lasted several weeks along with repeated scratching, making the skin thicken to protect itself.
Severity/urgency: not acutely dangerous, but it responds poorly to low-strength creams and usually needs a stronger medicine for longer.
When to see a doctor: after 2 weeks of treatment the patches are no thinner, or a single patch has not cleared at all after 2–3 months.
Type 3: on the shins and legs in older adults
Appearance: several patches on both shins, with dry, cracked skin around them that looks scaly. Some people also have leg swelling or varicose veins.
Cause: age-related dry skin, with skin oils decreasing after age 50, together with poor venous circulation in the legs.
Severity/urgency: it heals more slowly than elsewhere because the skin on the legs is thin and blood flow is lower.
When to see a doctor: swelling of one leg only, redness with heat and pain, an open sore, or fever. See a doctor immediately to rule out cellulitis.
This group often overlaps with rashes on the legs from poor circulation and cracked dry skin. Treatment therefore includes raising the legs, wearing compression stockings as advised by the doctor, and diligent use of moisturiser.
Type 4: on the backs of the hands and fingers
Appearance: patches 1–3 centimetres across on the backs of the hands, backs of the fingers or knuckles. The skin is dry and cracked, sometimes with small blisters.
Cause: frequent hand washing, contact with dish soap, detergent or hand sanitiser, or nickel allergy from rings and tools.
Severity/urgency: it affects daily life considerably, because hands are constantly in water and the rash keeps flaring.
When to see a doctor: the rash lasts more than 3 months, or you suspect an allergy to something at work. A skin patch test for allergy is advised.
A hand rash with deep, clear blisters on the sides of the fingers and palms is a different condition. Read about it in pompholyx (blisters on the palms and soles).
Type 5: in children and teenagers with allergic disease
Appearance: patches on the arms, legs or trunk together with an allergic eczema rash in the skin folds, dry skin all over, and often a history of allergic rhinitis or asthma.
Cause: skin that already has atopic dermatitis, so some patches take the coin shape instead of the usual pattern.
Severity/urgency: not dangerous, but it can resist low-strength creams more than ordinary allergic eczema.
When to see a doctor: the child scratches so much that they cannot sleep, the rash weeps or has yellow crusts, or there are widespread blisters with fever.
Skin care in children follows the same principles as childhood atopic eczema, with the doctor choosing the strength of medicine according to age and the location of the rash.
Type 6: with a secondary bacterial infection
Appearance: patches with dry honey-coloured yellow crusts, small pustules, more painful than itchy, and spreading unusually fast.
Cause: Staphylococcus aureus multiplying on skin that is inflamed and scratched.
Severity/urgency: the infection needs treatment too. If only a steroid is applied, the rash will not improve or will get worse.
When to see a doctor: within 1–3 days when you see yellow crusts or pus, and immediately if there is fever, swollen lymph nodes, or redness and heat spreading beyond the patch.
Type 7: from medicines or substances that touch the skin
Appearance: several patches that appear within a few weeks to a few months after starting a new medicine, or a rash only where a substance touches the skin, such as under a belt buckle or a watch.
Cause: isotretinoin, which makes the skin very dry, interferon, TNF inhibitors, or a contact allergy to substances such as nickel, fragrance and creams containing neomycin.
Severity/urgency: usually mild, but if the trigger is not stopped or changed, the rash keeps returning.
When to see a doctor: whenever you suspect the rash is linked to a medicine. Never stop a prescribed medicine on your own; consult the prescribing doctor first. For a suspected contact allergy, read contact dermatitis.
How is nummular eczema different from ringworm?
This is the most important question, because the treatments for the two conditions are completely different, and using the wrong one can make either rash worse.
Ringworm (tinea corporis): the edge of the ring is raised, red and scaly, and the centre is paler than the edge. The ring enlarges slowly, and there is usually one patch or only a few. It is contagious. A skin scraping under the microscope shows fungal threads.
Nummular eczema: an even red colour throughout, with no clearing in the centre, usually several patches on both sides. It is not contagious. A skin scraping shows no fungus.
Why you must not apply steroid cream to ringworm: steroids suppress the skin's local immunity, so the fungus spreads wider and the appearance changes until it is hard to diagnose (tinea incognito). Details are in ringworm: causes and how to tell it from eczema.
Why antifungal cream does not help nummular eczema: because the rash is not caused by fungus. Mixed creams that combine a steroid, an antifungal and an antibiotic in one tube make the rash fade temporarily and then return, and increase the chance of an allergy to the ingredients.
The most reliable method is for a doctor to scrape the scale and examine it under the microscope for fungus (KOH examination), which can be done in the consulting room with a result in a few minutes.
How is nummular eczema different from other round rashes?
Psoriasis: thick silvery-white scale, typically on the elbows, knees and scalp, and the nails may be pitted. Read more in psoriasis: causes.
Granuloma annulare: a smooth bumpy edge, no scale, rarely itchy, and common on the backs of the hands and feet. Read more in granuloma annulare.
Pityriasis rosea: it starts with one large patch for 1–2 weeks, then smaller oval patches appear on the trunk, lined up along the ribs. It clears on its own in 6–8 weeks.
Impetigo: yellow crusts from the very beginning. It is common in children and is contagious.
Contact dermatitis: the rash sits where a substance touched the skin, and its edge follows the shape of the object.
Superficial skin cancer (Bowen's disease) and cutaneous lymphoma (mycosis fungoides): uncommon, but they must be considered when a single patch has not cleared at all after 2–3 months of correct treatment. The doctor will take a biopsy.
How do doctors diagnose nummular eczema?
Most cases are diagnosed from the appearance of the rash and the history, but the doctor may order extra tests in the following situations.
Skin scraping under the microscope for fungus (KOH): whenever the rash is scaly and cannot yet be told apart from ringworm.
Bacterial culture: when there is pus, yellow crusts, or the rash does not respond to a first course of antibiotics.
Skin patch test for allergy: when the rash recurs several times, affects the hands, or a contact allergy is suspected. Test substances are taped to the back for 48 hours, then read again on day 3–4.
Skin biopsy: when the rash has not improved after 2–3 months of correct treatment, or its appearance does not fit nummular eczema.
Which creams are used for nummular eczema?
Nummular eczema often needs a higher-strength steroid cream than ordinary allergic eczema, because the patches are thick with a clear edge, and the low-strength creams sold over the counter are usually not enough. Choosing the medicine is the doctor's decision. Examples of commonly used approaches are below.
Medium- to high-strength steroid creams (the main treatment)
Mometasone furoate 0.1%: applied thinly once a day for 2–4 weeks. Often used for patches on the arms, legs and trunk.
Betamethasone valerate 0.1%: once or twice a day for 2–4 weeks.
Clobetasol propionate 0.05%: very high strength, for thick patches on the legs or backs of the hands. Use for no more than 2 weeks per course and no more than 50 grams per week. Do not use on the face, skin folds or groin.
Forms and how to apply
Use a cream for wet, weeping patches. For dry, thick patches use an ointment, which absorbs into the skin better.
Dose is measured in fingertip units: a line of medicine squeezed along the last joint of the index finger is 1 unit, enough to cover an area of about 2 palms.
For very thick patches, the doctor may have you apply the medicine and cover it with plastic or a damp cloth (occlusion or wet wrap) for a short period so the medicine penetrates deeper.
Once the patches are flat and no longer itchy, the doctor will gradually reduce the frequency, for example every other day for 1–2 weeks, before stopping. Do not stop suddenly just because the rash has only just faded.
Non-steroid creams
Tacrolimus 0.1% ointment: used once the rash has improved, or applied twice daily on 2 days a week on spots that often flare, to reduce relapses. It may sting or burn for the first 3–7 days.
Antibacterial creams (only when there is a secondary infection)
Mupirocin 2% or fusidic acid 2%: 2–3 times a day for 5–7 days, only on patches with yellow crusts. Do not use continuously for long, because bacteria can become resistant.
To choose the right group of itch creams, read more in how to choose the right anti-itch cream.
Which pills are used for nummular eczema?
Most rashes are controlled with creams and skin care. Oral medicines are used in specific situations.
Sedating antihistamines at bedtime: for example chlorpheniramine 4 milligrams or hydroxyzine 10–25 milligrams, which help you sleep and reduce night-time scratching. Antihistamines do not make the rash itself clear directly. See details in anti-itch and antihistamine pills: which to choose.
Oral antibiotics: for example cephalexin 500 milligrams four times a day or dicloxacillin for 7–10 days, when several patches are infected or there is fever.
Oral steroids: used very rarely and for the shortest time, because after stopping the medicine the rash often returns stronger than before (rebound).
Immunosuppressants for severe or widespread rash: for example methotrexate 7.5–15 milligrams once a week or cyclosporine 3–5 milligrams per kilogram per day, which require periodic blood tests of liver, kidney and blood counts. For those who also have atopic dermatitis, the doctor may consider dupilumab injections.
Besides medicines, a hospital with phototherapy equipment may use narrowband ultraviolet B light 2–3 times a week for widespread rashes that resist creams.
How many days does nummular eczema take to clear?
Itching: usually eases within 3–7 days of starting a cream strong enough.
Patches flattening: mostly 2–4 weeks. Patches on the shins in older adults may take 4–8 weeks.
Dark marks after the rash fades: people with darker skin often keep brown marks for 3–6 months, which gradually fade by themselves.
Recurrence: common. Many patients have a rash that comes and goes over months to years, especially in cool weather, and it often appears in the same places.
Why does nummular eczema keep coming back?
Stopping the medicine too soon, when the rash has faded but the inflammation under the skin has not settled.
Using a strength that is too low, so the patches only partly clear and then thicken again.
Still taking hot showers, using harsh bar soap, and not moisturising after the rash clears.
Still being exposed to something you are allergic to without realising it, such as a nickel belt buckle or fragrance in lotion.
A secondary bacterial infection that has not been treated.
Dry leg skin from poor circulation that has not been addressed.
How to care for your skin to reduce flare-ups
Bathe in warm, not hot, water for no more than 5–10 minutes, once or twice a day.
Replace bar soap with a gentle, fragrance-free cleanser and use it only on areas with sweat or dirt.
Apply moisturiser within 3 minutes after bathing, while the skin is still damp, at least twice a day. Adults use about 250–500 grams a week if the skin is dry all over. Read how to choose ingredients in how to choose a cream for dry skin.
Apply the steroid first, wait 15–30 minutes, then apply moisturiser over it on the days you are still using the medicine.
Keep nails short and press or use a cold compress instead of scratching.
Wear soft cotton clothing and avoid wool and synthetic fabrics that irritate the skin.
Do not set the air conditioner too cold, and place a bowl of water or a humidifier in the bedroom in cool weather.
If your legs swell, raise them to heart level for 15–30 minutes while resting, several times a day.
Dry skin is the main cause of this rash. Read detailed care advice in dry cracked skin (xerosis): causes and care.
What foods should you avoid with nummular eczema?
No food has been proven to cause nummular eczema in people in general. Avoiding many foods without a confirming test does not make the rash clear faster and may cause nutritional deficiency. Points worth knowing are below.
People who drink a lot of alcohol get nummular eczema more often and have flare-ups more easily. Reducing alcohol is therefore beneficial.
Some people with severe nickel allergy may flare from foods high in nickel, but this should be confirmed by a doctor with a patch test before changing your diet.
Drinking enough water helps overall skin health but does not replace moisturiser.
Warning signs that need a doctor immediately
Fever, redness and heat spreading beyond the patch, or red lines running up the arm or leg.
Pus, thick yellow crusts, or pain greater than itch.
Clear blisters spreading rapidly around the rash with fever, in someone with atopic dermatitis, which may be a secondary herpes infection (eczema herpeticum).
A rash spreading over the whole body within a few days.
A single patch that has not cleared at all after 2–3 months of correct treatment, has broken skin, or bleeds easily.
Common myths about nummular eczema
"A round rash is always ringworm": not true. Many conditions cause round rashes, and nummular eczema is one of the conditions most often misdiagnosed as ringworm.
"Steroid cream thins the skin, never use it": a steroid chosen at the right strength for the location and used in the amount and for the time the doctor sets is safe and necessary for this condition. Side effects usually come from buying strong medicine and using it on your own continuously for months.
"Nummular eczema is contagious": it is not contagious.
"It is from bad blood, so I need a detox medicine": there is no medical evidence for this.
"Once the rash is gone I do not need to apply anything": the skin is still prone to flare-ups, so keep applying moisturiser every day.
Summary
Nummular eczema is an inflamed rash of round, well-defined patches 1–10 centimetres across, with intense itching. It is not fungal and not contagious.
It differs from ringworm in being an even red throughout with no clear centre, usually with several patches on both sides, and a skin scraping shows no fungus.
Dry skin, hot water, harsh soap, skin injury, bacteria and contact allergy are the main triggers.
The main treatment is a medium- to high-strength steroid cream for 2–4 weeks together with moisturiser at least twice a day.
The rash often returns, especially in cool weather. Moisturising continuously and reducing the medicine gradually help reduce flare-ups.
What to do: if a round rash has not cleared after 2–4 weeks of antifungal cream, see a dermatologist for a skin scraping test before changing medicines yourself.
Frequently asked questions about nummular eczema
Is nummular eczema contagious? Will people in my home get it?
No. Nummular eczema is inflammation of the skin itself, not a germ that spreads to others. Sharing a bathroom, blankets or a bed does not cause the rash in people at home. If several people at home have a similar rash at the same time, think of other conditions such as ringworm or scabies, which are contagious. The exception is a rash with a secondary bacterial infection that has formed yellow crusts. During that time, keep towels separate until the infection has been treated, which usually takes about 5–7 days.
A round, itchy, scaly rash: is it ringworm?
It may or may not be. Ringworm usually has a raised scaly edge with a centre paler than the edge, whereas nummular eczema is an even red throughout, usually with several patches on both sides. But judging by eye alone can be wrong. The reliable method is for a doctor to scrape the scale and look for fungus under the microscope, with a result in a few minutes. Do not apply steroid cream on your own before you know the result, because if it is ringworm the fungus will spread wider, and do not keep applying antifungal cream if 2–4 weeks have passed with no improvement.
What cream should I use for nummular eczema?
The main medicine doctors use is a medium- to high-strength steroid cream, such as mometasone furoate 0.1% once a day or betamethasone valerate 0.1% for 2–4 weeks. Thick patches on the legs or backs of the hands may use clobetasol 0.05% for a short period of no more than 2 weeks. Once the rash has improved, the doctor may switch to tacrolimus 0.1% to reduce flare-ups. If there are yellow crusts, an antibacterial cream is added for 5–7 days. The choice of medicine and strength depends on the location, thickness of the rash and age, so it should be prescribed by a doctor.
Does nummular eczema go away on its own?
Some small, thin patches may clear on their own when the air is more humid and the skin is well cared for, but most do not clear quickly by themselves, and the longer it is left, the more the patches thicken from scratching and the harder they are to treat. Treatment with a cream strong enough, plus moisturiser, reduces itching within 3–7 days and flattens the patches in 2–4 weeks. Nummular eczema is a chronic condition that can return, so keep caring for the skin even after the rash is gone, and return to the doctor when the rash starts again so it can be controlled quickly.
Why does nummular eczema clear with treatment and then return in the same place?
Common reasons are stopping the medicine too soon when the rash has only just faded and the inflammation under the skin has not settled, using a strength that is too low, still taking hot showers and using harsh soap, or not moisturising after the rash clears. Some people are still exposed to something they are allergic to, such as nickel or fragrance, or have a bacterial infection that has not been treated. If it returns often, the doctor may reduce the medicine gradually, have you apply a preventive medicine 2 days a week on the same spots, and consider a skin patch test to find the allergen.
What should I avoid eating with nummular eczema? Do I need to avoid seafood?
There is no need to avoid seafood or any particular food, because no food has been proven to cause nummular eczema in people in general. Avoiding many foods without a confirming test does not make the rash clear faster. What has evidence of helping is reducing alcoholic drinks, because heavy drinkers flare more easily. Some people with severe nickel allergy may benefit from reducing foods high in nickel, but the allergy should first be confirmed by a doctor with a test. A more important factor than diet is caring for the skin so it does not become dry.
For similar rashes that can be confused with it, read red itchy rash all over the body: causes and itching at night: causes. For other skin condition articles, see all skin condition articles.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed November 1, 2026
The information in this article is general knowledge, not a diagnosis or an individual prescription. Nummular eczema looks similar to several other rashes and must be examined by a doctor. The choice of medicine, dose and length of treatment is the doctor's decision. Results vary from person to person.
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