Discoid eczema, also known as nummular eczema, is a chronic (long-term) skin condition that causes the skin to become itchy, reddened, dry and cracked. It can affect any part of the body, but is usually seen on the:
- lower legs
People with discoid eczema have circular or oval patches of eczema with well-defined edges. "Discoid" means disc-shaped and "nummular" means coin-shaped. Areas of discoid eczema can be a few millimetres to a few centimetres in size.
Other types of eczema include:
- atopic eczema (also called atopic dermatitis) - this often runs in families and is linked to other conditions, such as asthma and hay fever
- contact dermatitis - a type of eczema that occurs when the body comes into contact with a particular substance
- varicose eczema - a type of eczema that occurs on the legs, usually around varicose veins (swollen and enlarged veins)
How common is discoid eczema?
It is estimated that discoid eczema affects two people in every 1,000, which makes it one of the rarer types of eczema.
Discoid eczema tends to develop in adults and is rare in children. It is more common among men aged from 50 to 70 and women in their teens or twenties. When discoid eczema occurs in young women, they often have atopic eczema as well.
If discoid eczema is not treated it can last for months or even years. Even after treatment the condition can return, often with patches in the same places as before.
However, there are a number of different treatments available, such as emollients (moisturisers - treatments applied to the skin to reduce the loss of water from the skin) and topical corticosteroids. If you have discoid eczema, use emollients as often as possible to keep your skin moisturised. Corticosteroids can be applied to the patches when they flare up.
There are also some self-help measures you can follow, and additional medication if your eczema is infected or particularly severe. With the correct treatment, you can keep discoid eczema under good control. See Discoid eczema - Treatment for more information.
Discoid eczema causes distinctive circular or oval patches of eczema. They may be a few millimetres or several centimetres wide and are usually pink, red or brown.
Discoid eczema can be:
- dry - the patches are dry, cracked and scaly, but not itchy
- wet - the patches are bumpy and blistered (covered with small fluid-filled pockets) and ooze fluid. They may be very itchy and the fluid may dry and crust over.
Patches of discoid eczema may appear first as a dry patch, and then become wet and oozing. The patch may become drier and scalier, and sometimes clear in the middle.
Some people find the itching severe, and if it is bad at night this can affect your sleep. Other people may barely notice the itching. Discoid eczema may also cause a burning or stinging feeling.
You may just have one patch of discoid eczema, or you may have several patches. The skin between the patches will usually be unaffected, although it is often dry. The patches of discoid eczema can last for weeks or months if they are not treated.
Where the patches appear
Discoid eczema can appear anywhere on the body, but does not usually occur on the face or scalp. It most commonly occurs on the:
- lower legs
- trunk (the body, excluding the head, neck and limbs)
If you treat your discoid eczema and it then returns, the patches may be in the same place as before.
Other skin conditions
Discoid eczema may be confused with other skin conditions, particularly ringworm. This is a fungal skin infection that also causes a ring-like red rash. See the images in the slideshow above to compare it to other common skin conditions.
The cause of discoid eczema is unknown, although it is often accompanied by dry skin.
One theory is that having dry skin means your skin cannot provide an effective barrier against substances that come into contact with it. A previously harmless substance, such as soap, can then irritate (damage) your skin.
Contact dermatitis, a type of eczema caused by coming into contact with a particular allergen or irritant, may therefore have a role in causing discoid eczema.
Discoid eczema may also be linked to atopic eczema, which often occurs in people who are prone to eczema, asthma and hay fever ("atopic" means the tendency to develop eczema, asthma or hay fever). However, unlike atopic eczema, discoid eczema does not seem to run in families.
Other possible causes
Some medicines may also be associated with discoid eczema, as patches of eczema can appear in people taking:
- interferon and ribavirin - when they are used together to treat hepatitis C, an infection of the liver
- tumour necrosis factor (TNF) blockers- which are used to treat some types of arthritis, which causes pain and swelling in the joints
Dry environments or cold climates can make discoid eczema worse. Sunny or humid (damp) environments may make your symptoms better.
- An allergen is a substance that reacts with the body's immune system and causes an allergic reaction.
- An irritant is a substance that damages the skin physically.
As discoid eczema causes distinctive symptoms, your GP should be able to make a diagnosis by examining the affected areas of skin.
In some cases your GP may also ask questions or carry out some tests to rule out other causes. Possible tests include:
- patch testing to diagnose contact dermatitis (a skin condition caused by coming into contact with a particular substance) - this is when tiny amounts of different substances are applied to your skin to see if they cause a reaction
- a swab test to diagnose an infection - a swab is a small piece of absorbent material, such as gauze or cotton, attached to the end of a stick or wire. This is used to collect a sample of skin to test for bacteria that may cause an infection.
- examining the flakes of skin to diagnose a fungal skin infection, such as ringworm, which also causes a ring-like red rash
Your GP may refer you to a dermatologist (a doctor who specialises in treating skin conditions) if they are unsure of the diagnosis or if you need patch testing.
Although there is no simple cure for discoid eczema, during an eczema flare-up a variety of treatments can ease the symptoms.
Medication used to treat discoid eczema includes:
- emollients (to use all the time)
- topical corticosteroids (for flare-ups)
- oral corticosteroids (for severe flare-ups)
- antibiotics (for infected eczema)
- antihistamines (for severe itching)
There are many different preparations for each type of treatment. It is often a matter of practicality and personal preference to find the best preparation for you, and this may take time.
A range of emollient products and some topical corticosteroid preparations can be bought from pharmacies without a prescription. Some of them are cheaper to buy this way than with a prescription.
Ask your pharmacist for advice on the different products and how to use them. After asking you a few questions about your condition and any medicines you take or use, your pharmacist may decide it would be better for your GP to review your condition and its treatment.
If your eczema does not improve after one week of using an over-the-counter preparation, see your GP.
Emollients are substances that help to soften and smooth your skin to keep it supple and moist. They are one of the most important forms of treatment for all types of eczema. See the Health A-Z topic about Emollients for more information.
As discoid eczema can cause your skin to become dry and cracked, it is important to keep it moisturised to prevent it from becoming further irritated. Emollients prevent water being lost from the outer layer of the skin, and add water to the skin. They act as a protective barrier to keep the moisture in and the irritants out.
Choice of emollient
There are a variety of emollients available. Your GP will be able to recommend a suitable product if you have discoid eczema.
You may need to try a few different emollients to find one that works for you. You may also be prescribed a mix of emollients, for example:
- an ointment for very dry skin
- a cream or lotion for less dry skin
- an emollient to use on your face and hands
- a different emollient to use on your body
- an emollient to use instead of soap
- an emollient to add to bath water or use in the shower
The difference between lotions, creams and ointments is the amount of oil they contain. Ointments contain the most oil so can be quite greasy, but they are the most effective at keeping moisture in the skin. Lotions contain the least oil so are not greasy but can be less effective. Creams are in the middle.
If you have been using a particular emollient for some time, it may eventually become less effective, or it may start to irritate your skin. If this is the case, speak to your GP as another product can be prescribed instead.
How to use emollients
Use your emollient all the time, even if you are not experiencing symptoms. You may wish to consider keeping separate supplies of emollients at work or school.
To apply the emollient:
- Use a large amount.
- Smooth the emollient into the skin in the same direction that the hair grows.
- Do not rub the emollient in.
- For very dry skin, apply emollient every two to three hours.
- After a bath or shower, gently dry the skin and then immediately apply emollient, while the skin is still moist.
- Do not share emollients with other people.
The most common side effect of using emollients is a rash. If you have discoid eczema, your skin may be very sensitive and can become irritable with certain ingredients in an emollient. If your skin is irritated by the emollient, speak to your GP, who will be able to prescribe an alternative product.
Some emollients contain paraffin and can be a fire hazard. As certain emollient products are highly flammable, do not use them near a naked flame.
Emollients that are added to your bath can make your bath very slippery, so take care getting in and out of the bath. As long as you are aware of these hazards, you should be able to use emollients safely.
If you have patches of discoid eczema, your GP may prescribe a topical corticosteroid (one that is applied directly to your skin). Corticosteroids work by quickly reducing inflammation.
Corticosteroids are any type of medication that contains steroids, a type of hormone. Hormones are groups of powerful chemicals that have a wide range of effects on the body. See the Health A-Z topic about Topical corticosteroids.
You may be concerned about using medication that contains steroids. However, corticosteroids are not the same as anabolic steroids, which are sometimes used (illegally) by bodybuilders and athletes. When used correctly, corticosteroids are a very safe and highly effective treatment for eczema.
Choice of topical corticosteroid
There are different strengths of topical corticosteroids that can be prescribed depending on the severity of your eczema. Discoid eczema usually needs a stronger type of corticosteroid than those used for other types of eczema.
You may be prescribed:
- a cream to be used on visible areas, such as the face and hands
- an ointment to be used at night or for more severe flare-ups
If you need to use corticosteroids frequently, visit your GP regularly so they can check that the treatment is working.
How to use topical corticosteroids
When using corticosteroids, apply the treatment accurately to the affected areas. Always follow the directions on the patient information leaflet that comes with the corticosteroid, which will provide details about how much you should apply.
Do not apply the corticosteroid more than twice a day. Most people will only have to apply it once a day. To apply the topical corticosteroid, take the following steps:
- Apply your emollient first and wait several minutes before applying the topical corticosteroid, until the emollient has soaked into your skin.
- Apply a small amount of the topical corticosteroid to the affected area - see the box above for a guide on the amount to use.
- Use the topical corticosteroid until the inflammation has cleared up, unless otherwise advised by your GP.
Speak to your GP if you have been using a topical corticosteroid and your symptoms have not improved.
Topical corticosteroids may cause a mild burning or stinging feeling at first. In very rare cases, they may also cause:
- thinning of the skin - particularly in the crease of the elbow or knee joint
- telangiectasia (visible blood vessels) - particularly on the cheeks
- acne (spots)
- increased hair growth
Generally, using a stronger or larger amount of topical corticosteroid may increase your risk of side effects. For this reason, use the weakest and smallest amount possible to control your symptoms.
If you have a severe flare-up, your GP may prescribe oral corticosteroids. These contain steroids, as topical corticosteroids do, but are swallowed. See the Health A-Z topic about Corticosteroids for more information.
If oral corticosteroids are taken often or for a long time they can cause side effects, such as:
- affecting the growth rate of children
- high blood pressure (hypertension)
- osteoporosis (brittle bones)
For this reason, your GP is unlikely to prescribe oral corticosteroids more than once a year without referring you to a specialist (see referral, below).
If your eczema has become infected, you will usually be prescribed an antibiotic.
If you have an extensive area of infected eczema, your GP may prescribe an antibiotic to take orally (by mouth). The antibiotic most commonly prescribed is flucloxacillin, usually taken for one week. If you are allergic to penicillin, you may be prescribed clarithomycin instead.
If you have a small amount of infected eczema, you will normally be prescribed a topical antibiotic, such as fusidic acid or mupirocin. This means that the medicine is applied directly to the affected area of skin, in the form of an ointment or cream.
Topical antibiotics should normally be used for a week, or up to 10 days if necessary.
You can help prevent your eczema becoming infected by keeping your hands clean and you nails short. Try not to scratch as this can make infection more likely.
If you suspect that your eczema is infected, for example because there are weeping blisters in the patches of eczema, see your GP as soon as possible. The infection can spread quickly, and the use of corticosteroid creams can mask or further spread the infection.
Antihistamines are a type of medicine that work by stopping the effects of a substance in the blood called histamine. Your body often releases histamine when it comes into contact with an allergen. Histamine can cause a wide range of symptoms, including sneezing, watery eyes and itching.
Antihistamines may be prescribed during flare-ups of discoid eczema to cope with the symptom of itching, particularly if it is interfering with your sleep. However, they will not treat the damaged skin.
Antihistamines can have a sedating effect (make you drowsy), or can be non-sedating. If you are taking sedating antihistamines, avoid driving the next day if you still feel drowsy. The sedative effect is likely to be stronger if you drink alcohol.
See the Health A-Z topic about Antihistamines.
In some severe cases of discoid eczema, your GP may refer you for assessment and treatment by a dermatologist (a skin specialist). For example, your GP may refer you if the prescribed treatments are not successfully controlling your eczema.
Some of the treatments that a dermatologist may be able to offer you are explained below. These types of treatments are not suitable for everyone, and can only be carried out by experienced skin-care specialists.
Possible treatments include:
- phototherapy - where your eczema is exposed to ultraviolet (UV) light
- bandaging - where medicated dressings or wet wraps are applied to your skin
- immunosuppressant medication - a medicine that suppresses your immune system (the body's natural defence system)
- Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
Some people choose to use complementary therapies to treat eczema, such as herbal remedies. Although they may find these therapies helpful, there is often a lack of evidence to show that these remedies are effective in treating conditions such as eczema.
If you are thinking about using a complementary therapy, speak to your GP first to ensure that the therapy is safe for you to use. Make sure you continue to use any other treatments that your GP has prescribed.
- Avoid soaps and detergents, including liquid soaps, bubble bath and shower gels, if these irritate your skin. Use an emollient instead of soap.
- Minor cuts often trigger discoid eczema, so protect your skin, for example by wearing gloves.
- Lukewarm or cool baths or showers may reduce your itching. Remember to apply your treatments after your bath or shower.
- Keep your fingernails short to reduce skin damage from scratching.
- Make sure you use and apply your treatments as instructed by your GP or pharmacist. Treatment failure can be due to incorrect use.
How much topical corticosteroid to use
- Topical corticosteroids are measured in a standard unit called the fingertip unit (FTU).
- One FTU is the amount of topical steroid squeezed along an adult's fingertip.
- One FTU is enough to treat an area of skin twice the size of an adult's hand.
- You can see a Patient UK guide to how many fingertip units to use to treat different areas of the body here (PDF, 9.734mb – opens in a new window).