Outside-in or Inside-out? Top tips for making childhood eczema better

In developed countries the incidence of eczema has been increasing for several decades.  At the same time, children are tending to take longer to grow out of having eczema, leading to an even greater prevalence.  While it can be difficult to treat in a General Practice setting, eczema treatment is ripe for Primary Care expertise to make a big difference to a group of children who have an unpleasant but treatable condition.

Recently, I heard an experienced paediatric dermatologist try to squeeze all his eczema wisdom into about an hour long session.   What I learned was that by understanding the way that eczema works, I can be better at treating eczema.

There are many proposed models for what causes and perpetuates eczema.  Two of these are the ‘inside out’ and the ‘outside in’ models.  If you are interested in these things, there is much debate about whether eczema is caused by allergy and perpetuated by damaged skin versus being caused by a defective skin barrier which then leads to allergens penetrating the epidermis.  If you don’t care and just want to treat the eczema effectively, the answer is simple: do something about all the factors involved regardless of which is chicken or egg.

Here's how to do that:

1. Restoring the skin barrier

Think of the epidermis as being a brick wall.  In eczema all the mortar is falling apart and there are gaps between the bricks.  That means that the wall is leaky and does not protect the house from the elements.  What is needed is to repair the mortar.  In eczema, repairing the skin barrier requires oil.  This can be achieved in several ways.  The first thing that is needed is to use emollients. 

Of course there are many emollients available.  Whatever the treatment is, it needs to be one that the family will use often enough.  This requires the provision of large amounts so that the parents will be liberal in using it.  They need to be told to apply it often enough to keep the skin feeling greasy all the time.  Some creams are greasier than others.  Bigger is not always better though.  Sometimes families find the greasiest creams to be too oily and so they apply them less often.  It is important to make sure that they are happy with the cream prescribed.

As well as replacing oils, we need to make sure that whatever is there is not being taken away.  Soaps, shampoos and detergents need to be avoided.   Instead, encourage the use of water alone or with bath oils.  Aqueous cream contains sodium lauryl sulfate which is a mild detergent.  Aqueous cream should not be used as an emollient but can be used as hand soap (1).

2. Treating the inflammation

Returning to the inside out/ outside in way of thinking about eczema, restoring the barrier is not going to be effective on its own when there is inflammation present.  Inflammation requires steroid creams.  How strong a cream and how long it should be given depends on the severity of the eczema and how well it responds.  In short, the steroid cream should be prescribed at a strength that treats the eczema and for as long as necessary to resolve the inflamed skin.  It is very important to attack the eczema from every other angle at the same time so that the steroid cream is given the best possible chance to work and be stopped.

3. Addressing the itch

Treating eczema does not stop at using emollients and steroids.  The next issue to consider is the itch-scratch cycle.  Inflamed skin is itchy and scratched skin makes eczema worse.  Antihistamines can make a big difference during an exacerbation of eczema, not just to help with symptoms but also to speed recovery.

4. Treating drivers of inflammation

Another consideration is the possibility of something driving the inflammation.  Bacterial infection may be manifested as exudative or golden crusted areas.   Herpes virus infection will usually be evident either by the characteristic vesicles or the ulcerated lesions left behind.  Treatment of bacterial infection with oral antibiotics is sometimes needed.   Topical treatment with fucidic acid cream is often the preferred option.  Topical antibiotics must not be continued long term as this simply promotes resistant bacteria colonising the skin. 

Besides infection, there may be allergens that are identifiable.  Avoiding (e.g. specific foods) or minimising (e.g. house dust mite) these precipitants is important, though often difficult.

Having this four pronged approach is much more likely to be effective than being overly simplistic such as by just prescribing a steroid cream for a flare up of eczema.  Good explanation of the treatment and being supportive are both essential to the success of any plan.

I am told by paediatric dermatologists that they often don't use special secondary care treatments when they see children with eczema.  What they do is to use the same treatment that are available in primary care but use these treatments differently.  That sounds like an opportunity for us to make these dermatologists a bit more redundant.

Edward Snelson
@sailordoctor


Disclaimer: Other models of eczema pathogenesis are also available

References

1. National Eczema society - "Why Aqueous Cream is Bad for Eczema" http://www.eczema.org/aqeous
2. Drug Safety update - aqueous cream may cause irritation https://www.gov.uk/drug-safety-update/aqueous-cream-may-cause-skin-irritation