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Eczema nummulare
Coin-sized, round, sharply bordered patches that itch strongly — very often taken for ringworm. They need greasing, a strong enough ointment and patience.
Also known as: discoid eczema · coin-shaped eczema · microbial eczema
Open in the tool — with search and all the links →This compilation is for information and replaces neither medical diagnosis nor treatment. If you have symptoms, see a doctor.
Round to oval, sharply bordered patches of one to five centimetres, like coins laid on the skin — hence the name. At the start they are often moist and studded with tiny blisters, later dry, scaling and crusted, and they usually itch markedly. They sit most often on the lower legs, backs of the hands and forearms, less often on the trunk, and they often appear in numbers. Two mix-ups shape the course: because they are round and redder at the edge than in the middle, they are very often taken for ringworm and treated for months with antifungal cream — which does nothing. And because they are sharply bordered they get confused with psoriasis, which however scales more silvery and has different favourite places. The background is a disturbed skin barrier on dry skin, often set off by a small injury, an insect bite, a varicose vein backlog in the leg or a bacterial colonisation of the surface. That explains why this eczema mostly starts in winter and why it is more stubborn than others: the patches often persist for weeks to months and heal slowly from the middle outwards. It is not catching, and it does go away — the treatment simply needs more patience and considerably more greasing than most people expect.
A swab or a scale sample takes minutes. On ringworm, cortisone makes the redness disappear while the fungus keeps spreading — that is the most common avoidable detour with round patches.
These patches usually need a stronger ointment than an ordinary eczema, and over several weeks. Starting too weakly and stopping too early is the main reason it comes back.
Between the patches the skin is dry as well, and that is where the next ones arise. Cream the whole affected part of the body daily, not just the spots.
Honey-yellow crusts, weeping and an edge that spreads fast: then a bacterial colonisation is involved, and that is treated separately. This picture is especially common with nummular patches.
Swollen legs, brownish discolouration and visible veins change the treatment: without compression the eczema there heals badly, with compression often by itself.
With several, stubborn or repeatedly returning patches a look at the blood sugar is worthwhile — an unrecognised diabetes explains both: the dryness and the poor healing.
Hot water eases the itching for minutes and worsens it for hours. Lukewarm, short, no soap on the patches, then cream at once.
Then the picture belongs checked once more — with a swab, if needed with a small tissue sample. A single round patch that stays for months, grows and does not itch is something else.
A scratch eczema from mites is often treated as eczema — and spreads under cortisone. Night itching, burrows between the fingers and several people in the household tell them apart.
This eczema usually needs a stronger cortisone ointment than others and for longer — with too weak a strength and too short an application it does not clear, and that is the most common reason for a chronic course. It is applied to damp skin after showering. Dryness is almost always involved; without a rich base it returns. With weeping areas, secondary bacterial colonisation is considered.
The coin-shaped patches measure one to five centimetres and last weeks to months without adequate treatment. Men over fifty are most often affected, usually in winter, on the lower legs and forearms. The itch is stronger than the appearance suggests. Treatment is a stronger cortisone ointment over two to four weeks and then tapering — too weak and too short is the most common reason it does not clear.
One to five centimetres, usually several at once, with a clear border to healthy skin. The shape is so even that it stands out — and that is exactly what leads to the mix-up with ringworm.
At the start there are tiny blisters and weeping; after days it dries to a scaling, crusted surface. This sequence tells it apart from psoriasis, which scales dry and silvery from the start.
Ringworm has an emphasised, slightly raised rim and a clearly paler middle — it grows outwards as a ring. In nummular eczema the whole area is involved. If in doubt a swab decides, and it is taken before the cortisone cream.
An insect bite, a graze, an irritated spot under a plaster — and weeks later a round patch sits there, sometimes with others beside it. This history helps with the classification.
Patches on the lower legs with swollen legs, brownish discolouration and visible veins belong to a context of their own: stasis eczema. Then compression is part of the treatment.
Weeks to months are the rule, not the exception, and the patches heal slowly from the middle outwards. Anyone giving up after ten days does not see the success — that is the most common reason for the impression that nothing helps.
Normal with the eczema itself. If it rises together with warmth, pain and fever, the skin has become infected as well — which is more common with this picture than with other eczemas.
An unrecognised diabetes causes dry skin, more skin infections and poorer healing — and nummular patches occur more often with it. A value worth checking here.
An underactive thyroid dries the skin out and so prepares the ground. It does not explain the eczema on its own but makes it more stubborn.
An empty store lowers the itch threshold. With an eczema that is kept going mainly by the scratching, that is a point to work on.
With patches that heal badly and keep breaking open, a lack is among the few easily correctable reasons.
For the renewal of the outer skin and for the healing of the scratched places. With patches that keep breaking open a lack belongs checked.
Without vitamin C no stable collagen forms, and the scratched place closes less well. With a one-sided diet, smoking and alcohol the intake is often tighter than assumed.
Building blocks of the fats between the skin cells — from inside an addition to greasing from outside, not a replacement for it.
An empty store lowers the itch threshold and so keeps going the circle of itching and scratching that maintains these patches.
With eczema and a low starting value an improvement was measured — 20–50 µg (800–2000 IU) a day over 8–12 weeks. Nummular eczema itself is not separately studied.
1–2 g EPA+DHA a day over 8 weeks. With this form drying out is the strongest trigger — short lukewarm showers and creaming straight afterwards works more reliably than anything swallowed.
Clearly effective with proven deficiency, useless without. Take only with a documented deficiency — excess is harmful.
This form affects mostly men over fifty and women after menopause — both with skin that is becoming drier. The common denominator is the barrier, not the sex.
Nummular eczema nearly always sits on dry skin and appears more in winter. Two portions of oily sea fish a week supply omega-3; greasy care from outside works faster.
Eases itching briefly. Nummular eczema nearly always sits on dry skin — greasy ointments work considerably more here.