Eczema is the term used to describe skin conditions that cause the skin to become itchy, red, inflamed and cracked.
There are seven different types of eczema, including atopic dermatitis, contact dermatitis, dyshidrotic eczema, nummular eczema, seborrheic dermatitis, and stasis dermatitis. However, ‘eczema’ and ‘dermatitis’ are often used interchangeably.
Dr Roger Henderson looks at what eczema is, what it looks like, the different causes of eczema, and how to get rid of it.
What is eczema?
Eczema is an inflammation of the skin that causes the skin to become itchy, red, dry and cracked.
Atopic eczema (atopic dermatitis) is the most common form of eczema and is a long-term (chronic) skin condition in most people, although it can improve over time, particularly for children – about two thirds will grow out of it as they get older.
Atopic eczema affects about 10 to 20 per cent of schoolchildren and 3 to 5 per cent of adults in the UK, and it’s getting more common. An increase has been seen over the past 30 years, for reasons that are far from clear.
Eczema and allergens
It seems likely though that increasing exposure to allergens (protein substances to which people can become allergic), such as house dust mite and other environmental factors, have been the main causes of this increase.
Eczema and cleanliness
It is also thought that increasing ‘cleanliness’ or overuse of antibacterial/antiseptic products can cause a switch in the immune system that leads to more allergies.
Eczema and irritant chemicals
Although some older industrial practices have reduced the level of exposure of workers to irritant chemicals, there are still plenty of examples of poor practice, or of inadequate care, being taken at the individual level in handling materials known to potentially cause irritant contact eczema.
Eczema is associated to a varying degree with a number of symptoms including the following:
Eczema and itching
Itching is the main symptom, and without it, a rash is not due to eczema (unless the itch has been improved by treatment).
Itch is also a common feature of many other skin conditions – as well as being a symptom of a range of diverse medical conditions not primarily to do with the skin. So, although it’s an ‘essential’ symptom when diagnosing eczema, it’s not a symptom that is specific to eczema alone.
We still do not fully understand what causes itch, but nerve fibres specialised in transmitting the itch sensation appear to exist within the skin. Like other nerves, these are ultimately connected to the spinal cord and so to the brain. It used to be thought that the sensation of pain travelled along the same nerve fibres as for itch, but this now seems to be unlikely.
Interestingly, the two sensations can act against each other. Relief from severe itching may sometimes be had from inflicting pain instead, as might be seen in someone who prefers the discomfort of a very hot bath to that of constant itching. The act of scratching may itself cause nerve signals to travel down the pain fibres, blocking the sensation of itch from being experienced.
Eczema and redness
Increased redness of the skin usually means increased blood flow. An extensive network of tiny blood vessels (capillaries) is present in the deeper layers of the skin that project loops of smaller vessels into the more superficial layers.
The very top layer of skin is composed of dead skin cells and has no blood supply, so a superficial cut to this level will not bleed. When skin is inflamed the local network of blood vessels widens, increasing the flow of blood and making it red.
The process of inflammation in eczema is complex and can be triggered by a range of factors, but an important additional one to take into account when eczema flares up is the presence of bacterial infection.
When bacterial infection gets into the deeper layers of the skin, there’s usually a marked increase in redness and heat from the tissues. Recognising that this may be due to infection is important in bringing the eczema under control. In babies, it is often the face that is most commonly affected.
Eczema and thickening
The skin of areas of eczema that have been inflamed for a while are usually much thicker than unaffected skin. Mainly this occurs as a protective response of the skin to the repeated trauma of scratching or rubbing.
Eczema often affects the skin in areas around joints such as the elbow, behind the knees and in front of the ankles (the ‘flexures’), where the skin also needs to be particularly flexible.
Commonly, one will see splits in the skin here (fissures) because the thickened skin is unable to bend as it would normally.
The microscopic study of skin structure in eczema shows there is less adhesion between the skin cells, particularly in the upper layers of the skin.
This contributes to scaling and makes it easier for skin bacteria to get into the deeper layers, between the gaps. It also makes it possible for tissue fluids to ooze between the cells and, if sufficient, to gather into collections or blisters.
Small blisters may be seen in active eczema but occasionally large ones may occur, either due to the particular nature of the eczema or because of added skin infection, when the blisters may be filled not only with clear fluid but also pus.
The fluid that oozes from inflamed skin is rich in protein. When this dries out in contact with air the protein is left behind as a crusty deposit. Often this occurs in conjunction with infection, when the infected crusts typically have a golden colour.
A similar crusting is seen in the infectious skin condition called impetigo, which is commonly seen in children of primary school age because it's easily passed on by touching.
In impetigo, treating the infection eliminates the problem. But it's of course only part of what's required in eczema. Often doctors refer to infected eczema as being 'impetiginised'.
Grades of eczema
A useful extra way to classify eczema is based on the degree of activity and for how long the eczema has been active:
‘Acute’ in medical language means of rapid onset. Often conditions that come on over a short period of time are also quite vigorous in their activity, although strictly speaking ‘acute’ should not be taken to be another word for ‘severe’.
Acute eczema would therefore be an area that recently flared up and would be red, probably also have blisters and possibly some oozing or crusts.
‘Chronic' properly means long-standing. Once the initial phase of activity has died down, a bit of skin that has been eczematous for a while is dry, scaly, thickened and cracked.
At any stage of eczema, it can become infected. This won’t always be obviously different from acute eczema, unless there are pus-filled blisters. With experience, one can usually discern the golden crust of infection and pick up the other clues that suggest infection.
One can combine the types (atopic, seborrhoeic, discoid, etc) with the grade (acute, chronic, infected) and end up with a reasonable classification system of eczema. This, however, looks a lot simpler on the page than it is in reality!
Types of eczema
Eczema is divided into a small number of subgroups based largely on the factors that may be most important in causing eczema in any one individual. But it’s important to recognise that the symptoms and appearance of the skin in all these types can be exactly the same.
Also, the classification system is far from perfect as it is often difficult or impossible to accurately say what causes eczema to occur in any one person. The lines of treatment of the different types of eczema are also similar.
Atopic is the ‘allergic’ type often seen in people who also have hay fever or asthma and is the most common type of eczema with a typical set of skin symptoms. Around 20 per cent of schoolchildren are believed to have some level of atopic eczema but many of these no longer have it by their late teens.
Although around one in thirty adults have atopic eczema, it is uncommon for it to first appear after the age of 21. Having parents with eczema makes it more likely that it will occur (80 per cent risk if both parents have it, 60 per cent if only one parent has it) and in general it is becoming more common.
Allergic contact is due to skin contact to a substance to which the individual is sensitive. The same substance does not cause eczema in a person who is not sensitive to it.
Irritant contact is due to skin contact with irritating chemicals, powders, cleaning agents, etc. Contact with such a substance is likely to cause eczema in any person, although a degree of individual variation still exists.
Discoid generally appears as discrete islands of eczema on a background of normal skin.
In infants, seborrhoeic eczema appears in the nappy area and the scalp. In adults, also appears on the scalp and eyebrows, and in the skin creases between the nose and sides of the mouth. It can be caused by an increased sensitivity to yeast living on the skin.
Other types of eczema
Other types of eczema in a miscellaneous group include:
Eczema of the legs caused by varicose veins (varicose/gravitational eczema).
Pompholyx: an intensely itchy form located on the hands and composed of small or (sometimes) large blisters.
While there is no specific cure for eczema, there are a few things you can do to manage the condition and avoid flare-ups. Eczema treatment is generally effective in most people – although severe eczema can be difficult to get rid of – and consists of three key areas: irritant avoidance, moisturising the skin and using steroid creams if required.
It is unusual to be able to identify and eliminate a single agent causing the skin reaction, and many people with eczema have to settle for improving the condition rather than getting rid of it altogether, with flare-ups often occurring for no obvious reason.
However, basic tips to reduce skin irritation include:
Avoiding scratching the skin whenever possible (although this can be very tricky!).
Try not to scratch with your nails. Keep them cut short and rub the skin rather than scratch it if you feel you have to.
Avoid biological detergents and always rinse clothes well after washing them.
Try to avoid fluctuations in skin temperature.
Use a simple soap substitute rather than perfumed soaps and bubble baths (these dry out the skin) and gently pat the skin dry with a soft towel after showering or bathing rather than rubbing it hard.
Avoid harsh clothing next to the skin such as wool.
Dry skin is a key trigger for atopic eczema so keeping it well moisturised is essential in helping to prevent flare-ups. Emollients is the general term given to moisturising creams, lotions, ointments and additives for the bath or shower that can all help keep the skin supple and moist and so reduce the chance of an eczema flare.
Using an emollient regularly several times a day is vital in helping prevent eczema problems and there are a great many options now available.
Key points to remember are:
Use them liberally, and every day even when the skin appears normal. You cannot overuse them.
Ointments often last longer than creams and can be more moisturising but can be greasy and messier to use.
Rub them into the skin in the direction of hair growth rather than against it.
Consider using pump dispensers rather than pots of ointments or creams to help prevent infection.
Add an emollient to the bath or an emollient shower gel to help prevent the skin from drying out as baths and showers dry the skin.
Steroid creams and ointments
If simple moisturisers do not stop flare-ups then a topical steroid (cream or ointment) may be required. These work by reducing skin inflammation and vary from very mild to strong with the strongest ones having the greatest effect but also the biggest risk of side effects if used long-term regularly. As a general point, steroid creams should be used if the skin is moist, and ointments if it is dry.
For most people, one to two weeks of topical steroid treatment is enough to treat an eczema flare, although a longer course is sometimes needed, with the weakest strength needed to do the job being preferred. If there is no improvement after a week or so, then a stronger strength may be required.
Usually applied once or twice a day these are put onto the affected area of skin, unlike emollients which are applied all over the body.
It is important not to apply too much steroid to the skin and so it should be applied in what is called a fingertip unit – this is the amount of cream or ointment that fits on a fingertip from the end of the finger to the first finger crease. One fingertip unit is enough to treat a skin area twice the size of the flat of your hand with the fingers together. After putting a topical steroid onto the skin always wash your hands (but not if it is the hands that need treating) and use emollients as normal too. Use your emollient first, wait about 10 minutes then put the steroid onto the skin when it is still moist.
Occasionally, eczema can become infected and a course of antibiotics may be required. If this occurs then the best practice here is to dispose of the creams and ointments you have and obtain a fresh supply. This reduces the risk of contaminated creams continuing to infect the skin.
Although irritant avoidance, emollients and topical steroids are usually all that are required to treat eczema there can be occasions when further treatment is required, sometimes under the care of a skin specialist (a dermatologist). Examples of such treatments include:
Tar shampoos for severe scalp eczema
Skin soaks if the eczema is wet and weeping
Topical immunomodulators such as tacrolimus ointment and pimecrolimus cream. These became available almost 20 years ago and are licensed for use in people over the age of 2 where other treatments have failed, although these should not be used on infected skin.
Last updated: 16-09-2020
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