The term eczema refers to a set of clinical characteristics. Classification of the underlying diseases has been haphazard and unsystematic, with many synonyms used to describe the same condition. A type of eczema may be described by location (e.g., hand eczema), by specific appearance (eczema craquelure or discoid), or by possible cause (varicose eczema).
- Atopic dermatitis(aka infantile e., flexural e., atopic dermatitis) is an allergic disease believed to have a hereditary component and often runs in families whose members also have asthma. Itchy rash is particularly noticeable on head and scalp, neck, inside of elbows, behind knees, and buttocks.
- Contact dermatitisis of two types: allergic (resulting from a delayed reaction to some allergen, such as poison ivy or nickel), and irritant (resulting from direct reaction to a detergent, such as sodium lauryl sulfate, for example). Some substances act both as allergen and irritant (wet cement, for example). Other substances cause a problem after sunlight exposure, bringing on phototoxic dermatitis. About three quarters of cases of contact eczema are of the irritant type, which is the most common occupational skin disease. Contact eczema is curable, provided the offending substance can be avoided and its traces removed from one’s environment.
- Xerotic eczema(aka asteatotic e., e.craquele or craquelatum, winter itch, pruritus hiemalis) is dry skin that becomes so serious it turns into eczema. It worsens in dry winter weather, and limbs and trunk are most often affected. The itchy, tender skin resembles a dry, cracked, river bed. This disorder is very common among the older population
- Seborrhoeic dermatitis or Seborrheic dermatitis (“cradle cap” in infants) is a condition sometimes classified as a form of eczema that is closely related to dandruff. It causes dry or greasy peeling of the scalp, eyebrows, and face, and sometimes trunk. The condition is harmless except in severe cases of cradle cap. In newborns it causes a thick, yellow crusty scalp rash called cradle cap, which seems related to lack of biotin and is often curable.
- Dyshidrosis(aka dyshidrotic e., pompholyx, vesicular palmoplantar dermatitis, housewife’s eczema) only occurs on palms, soles, and sides of fingers and toes. Tiny opaque bumps called vesicles, thickening, and cracks are accompanied by itching, which gets worse at night. A common type of hand eczema, it worsens in warm weather.
- Discoid eczema(aka nummular e., exudative e., microbial e.) is characterized by round spots of oozing or dry rash, with clear boundaries, often on lower legs. It is usually worse in winter. Cause is unknown, and the condition tends to come and go.
- Venous eczema(aka gravitational e., stasis dermatitis, varicose e.) occurs in people with impaired circulation, varicose veins and edema, and is particularly common in the ankle area of people over 50. There is redness, scaling, darkening of the skin and itching. The disorder predisposes to leg ulcers.
- Neurodermatitis(aka lichen simplex chronicus, localized scratch dermatitis) is an itchy area of thickened, pigmented eczema patch that results from habitual rubbing and scratching. Usually there is only one spot. Often curable through behavior modification and anti-inflammatory medication. Prurigo nodularis is a related disorder showing multiple lumps.
- Autoeczematization(aka id reaction, auto sensitization) is an eczematous reaction to an infection with parasites, fungi, bacteria or viruses. It is completely curable with the clearance of the original infection that caused it. The appearance varies depending on the cause. It always occurs some distance away from the original infection.
- There are also eczemas overlaid by viral infections ( herpeticum, e. vaccinatum), and eczemas resulting from underlying disease (e.g. lymphoma). Eczemas originating from ingestion of medications, foods, and chemicals, have not yet been clearly systematized. Other rare eczematous disorders exist in addition to those listed here.
The cause of eczema is unknown but is presumed to be a combination of genetic and environmental factors.
The hygiene hypothesis postulates that the cause of asthma, eczema, and other allergic diseases is an unusually clean environment. It is supported by epidemiologic studies for asthma. The hypothesis states that exposure to bacteria and other immune system modulators are important during development, and missing out on this exposure increases risk for asthma and allergy.
While it has been suggested that eczema may sometimes be an allergic reaction to the excrement from house dust mites, with up to 5% of people showing antibodies to the mites, the overall role this plays awaits further corroboration.
The failure of the body to metabolize linoleic acid into y-linoleic acid (GLA) was thought to be a possible cause of eczema, however the largest and best reported studies into the efficacy of GLA supplements in the treatment of eczema failed to show any benefit.
Diagnosis of eczema is based mostly on history and physical examination. However, in uncertain cases, skin biopsy may be useful.
There is no known cure for eczema; therefore, treatments aim to control the symptoms by reducing inflammation and relieving itching.
Corticosteroids are highly effective in controlling or suppressing symptoms in most cases. For mild-moderate eczema a weak steroid may be used (e.g. hydrocortisone), while in more severe cases a higher-potency steroid (e.g. clobetasol propionate) may be used. In severe cases, oral or injectable corticosteroids may be used. While these usually bring about rapid improvements, they have greater side effects.
Topical immunosuppressants like pimecrolimus and tacrolimus effectively suppress the immune system in the affected area, and appear to yield better results in some populations.
When eczema is severe and does not respond to other forms of treatment, systemic immunosuppressants are sometimes used. These dampen the immune system and can result in improvements to the person’s eczema. However, immunosuppressants can cause side effects. Some require regular blood tests and be closely monitored. The most commonly used immunosuppressants for eczema are ciclosporin, azathioprine and methotrexate.
Anti-itch drugs, often antihistamines may reduce the itch during a flare up of eczema, and the reduced scratching in turn reduces damage and irritation to the skin (the “itch cycle”). However, in some cases, significant benefit may be due to the sedative side effects of these drugs, rather than their specific antihistamine effect.
Capsaicin applied to the skin acts as a counter irritant (see gate control theory of nerve signal transmission).
Hydrocortisone applied to the skin aids in temporary itch relief.
Temporary yet significant and fast-acting relief can be found by cooling the skin via water (swimming, cool water bath or wet washcloth), air (direct output of an air conditioning vent), or careful use of an ice pack (wrapped in soft smooth cloth, e.g., pillow case, to protect skin from damage).
Eczema can be exacerbated by dryness of the skin. Moisturizing is one of the most important self-care treatments for eczema. Keeping the affected area moistened can promote skin healing and relief of symptoms. Soaps and detergents should not be used on affected skin because they can strip natural skin oils and lead to excessive dryness.
Moistening agents are called emollients. In general, it is best to match thicker ointments to the driest, flakiest skin. Light emollients may not have any effect on severely dry skin. Moisturizing gloves (gloves which keep emollients in contact with skin on the hands) can be worn while sleeping. Generally, twice-daily applications of emollients work best. Ointments, with less water content, stay on the skin longer and need fewer applications, but they can be greasy and inconvenient. Steroids may also be mixed in with ointments.
For unbroken skin, direct application of waterproof tape with or without an emollient or prescription ointment can improve moisture levels and skin integrity which allows the skin to heal. This treatment regimen can also help prevent the skin from cracking, as well as put a stop to the itch cycle. The end result is reduced lichenification (the roughening of skin from repeated scratching). Taping works best on skin awayfrom joints.
There is a disagreement whether baths are desirable or a necessary evil. For example, the Mayo Clinic advises against daily baths to avoid skin drying. On the other hand, the American Academy of Dermatology claims “it is a common misconception that bathing dries the skin and should be kept to a bare minimum” and recommends bathing to hydrate skin. They even suggest up to 3 short baths a day for people with severe eczema. According to them, a moisturizer should be applied within 3 minutes to trap the moisture from bath in the skin.
Ceramides, which are the major lipid constituent of the stratum corneum, have been used in the treatment of eczema. They are often one of the ingredients of modern moisturizers.
The terms “hypoallergenic” and “doctor tested” are not regulated and no research has been done showing that products labeled “hypoallergenic” are in fact less problematic than any others.
Various measures may reduce the amount of mite antigens, in particular swapping carpets for hard surfaces. However, it is not clear whether such measures actually help with eczema. A controlled study suggested that a number of environmental factors such as air exchange rates, relative humidity and room temperature (but not the level of house dust mites) might have an effect on the condition.
Patients can also wear clothing designed specifically to manage the itching, scratching and peeling associated with eczema.
Light therapy (or deep penetrating light therapy) using ultraviolet light can help control eczema. UVA is mostly used, but UVB and Narrow Band UVB are also used. Overexposure to ultraviolet light carries its own risks, particularly potential skin cancer from exposure.
When light therapy alone is found to be ineffective, the treatment is performed with the application (or ingestion) of a substance called psoralen. This PUVA (Psoralen + UVA) combination therapy is termed photo-chemotherapy. Psoralens make the skin more sensitive to UV light, thus allowing lower doses of UVA to be used. However, the increased sensitivity to UV light also puts the patient at greater risk for skin cancer.
There has not yet been adequate evaluation of the effects of altering the diet to reduce eczema. There is some evidence that infants with eczema and an established egg allergy may have a reduction in symptoms if eggs are eliminated from their diets. Benefits have not been shown for other elimination diets, but more research is needed to show whether dietary changes may help. Establishing there is, in fact, a food allergy before dietary change could avoid unnecessary major lifestyle changes. Those with eczema may be especially prone to misdiagnosis offood allergies.
Dietary supplements are commonly used by people with eczema. Probiotics are live microorganisms taken orally, such as the Lactobacillus bacteria found in yogurt. They are not effective for treating eczema in older populations, but some research points to some strains of beneficial microorganisms having the ability to prevent the triad of allergies, eczema and asthma, although in rare cases some species of probiotic bacteria have a very small risk of infection in those with poor immune system response. Exposure to probiotics in infancy may shape the immune system to resist eczema. Certain strains of probiotics are more effectual than others, and the timing of administration is also important.