What should I apply FIRST ? Emollient or Topical corticoteroid ?

Emollients and topical steroid creams are often prescribed by the doctors for inflammatory skin conditions especially eczema/dermatitis. Both products are useful for treating such skin conditions. They are like "peanut and butter" - perfect combination for a toasted bread. 

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 Often, emollients comes in different formulations - ointment, emulsion (water in oil; oil in water) , cream, lotion etc. They are meant to be applied liberally on your skin to moisturise, thus hydrate your skin all the time. In addition, emollients can always act as protective barrier that prevent skin contact with irritants. Hence, you need to apply them to the affected area(s) as frequent as possible. Do not have to worry about overdoing! What emollient do is to keep your skin hydrated. 

Topical steroid, on the other hand, is prescribed for "flare-up". When your skin becomes inflamed ( reddened, swollen, blistered, thickened), topical steroid is really good in treating this. In fact, the prescriber always use topical steroid, starting at the lowest potency, to treat your eczema or dermatitis. 

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Here comes the question, both are prescribed together - which one should I apply first ? 

Emollient ? or Topical Steroid ? 

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It has been a long debate among healthcare professionals whether which one should be applied first - to have it best effect on the treatment. 

Some argued that you should apply emollient first - to hydrate your dry skin first. Then, you can apply steroid. This improves the absorption of topical steroid into your skin,thereby, increasing the effectiveness of treatment. 

Some argues that you should apply topical steroid first. This is because if you apply emollient first, you would have dilute the concentration of steroid, thus, reducing the effectiveness of treatment. 

I looked up several websites and articles, and here is what I got:- 

For those who have some dry skin conditions ( in which their skin are very dry, even exfoliate and become flaky), apply emollient first is important. Here is the suggestion - apply emollient liberally on your skin (especially those affected area) 20-30 minutes before you apply topical steroids (1)(2). 

When the skin is hydrated, it becomes easier for you to spot the angry/red are(s) which then you can apply topical steroid on them to reduce the inflammation. One more reason is that - applying emollients can remove the flakes that could then increase the absorption of topical steroid. (1) . However, make sure that the skin is not too slippery when apply topical steroids. 

Applying topical steroid first before emollient is mainly based on the fact that topical steroid may be diluted by emollient. Some proposed "emollient sandwich" model whereby applying emollient after topical steroid can provide an occlusive effect , therefore enhance the effect of topical steroid in treating "flare-up". (3)

In fact, there are a lot factors that affect the absorption of topical steroids into the skin including formulations of emollients and topical steroids (composition, particle size, lipid-water partition coefficient, ionisation, local effects) , skin condition ( hydration level, level of subcutaneous skin damage, anatomical site), reservoir effect, application dose ( concentration , amount) etc.

A guidelines suggested the application of emollient first owing to the fact that topical steroid may be more effective and reduction of the risk of steroid spreading to the unaffected area (healthy skin) if emollient is applied straight after the use of topical steroid.

Still, there is no clear cut evidence as in which one should be applied first. 

Summary 

1. Emollient should be applied first (to hydrate the skin) , then apply topical corticosteroid on the red/angry affected area (15-30 minutes after) , if possible.  (my personal view based on evidence I read).

(Most of time, you only need to use topical steroid for few times (Once daily, twice daily or as directed) for short term, while you always use emollient as frequent as you like )

2. Make sure you use emollient liberally (a few times daily as long as your skin is hydrated)

3. Only use topical steroid for "flare-up" - inflamed, red, itchy skin. Use appropriate amount (fingertip unit) [a guide table is provided below].And,  DO NOT use THINLY or SPARINGLY.

Table 3: Approximate number of adult finger tip units (FTU) of corticosteroid needed per application for children with eczema15 *

	3–6 months old	1–2 years old	3–5 years old	6–10 years old
One entire arm and hand	1	1.5	2	2.5
One entire leg and foot	1.5	2	3	4.5
Torso (front)	1	2	3	3.5
Back and buttocks	1.5	3	3.5	5
Face and neck	1	1.5	1.5	2

* Note that these values are a guide and will be influenced by the size of the child

Guidelines obtained from bpac article - Topical corticosteroids for childhood eczema: clearing up the confusion

References 

http://patient.info/health/moisturisers-emollients-for-eczema

http://www.mims.co.uk/article/591931/apply-emollients-topical-steroids

http://www.academia.edu/7368921/Topical_steroid_or_emollient_which_to_apply_first_A_critical_review_of_the_science_and_debate

http://www.bpac.org.nz/BPJ/2009/September/docs/bpj23_corticosteroids_pages8-13.pdf

http://www.bpac.org.nz/2016/topical-corticosteroids.aspx