Reading labels for eczema and atopic skin

Here is a thing most people never notice. The ingredients in an ordinary moisturiser and the active ingredients in a regulated skin protectant drug are largely the same list.

The same ingredients, two regulatory worlds

The skin protectant monograph names its permitted actives with concentration ranges, and they are not exotic:

Petrolatum, 30 to 100 percent. Glycerin, 20 to 45 percent. Dimethicone, 1 to 30 percent. Lanolin, 12.5 to 50 percent. Zinc oxide, 1 to 25 percent. Allantoin, 0.5 to 2 percent.

And Colloidal oatmeal, at “0.007 percent minimum”, which is the lowest threshold in the list by a long way and worth knowing when a product leans on oatmeal in its marketing.

A jar claiming to protect skin is a drug and states its active and its strength. A jar with identical contents claiming to moisturise is a cosmetic and states nothing. Same shelf, same ingredients, and one of them tells you how much.

That is the drug and cosmetic line, set out in full in the guide on which claims are regulated, and eczema is the category where it is most useful to know about.

Occlusive, humectant, emollient

Three jobs, and a good product for dry skin usually does all three.

Occlusives stop water leaving. Petrolatum is the reference standard and nothing outperforms it. It is not absorbed, it does not do anything biologically, and that inertness is the point.

Humectants draw and hold water. Glycerin is the workhorse, hyaluronic acid is the expensive one, and both need something over the top in very dry conditions or they can pull moisture out of the skin rather than into it.

Emollients fill and smooth. Ceramides belong here and have the additional argument that they are components of the barrier itself.

Reading a jar for which of these it does tells you more than any ingredient count.

The suspects worth narrowing

Atopic skin has a compromised barrier, so it lets more in, which is why contact allergy is more common and why identifying triggers matters more here than for most people.

Fragrance is the first suspect and the hardest to pin down, because one word can stand for dozens of substances. The European baseline patch test series includes fragrance mix I and its named constituents, and the guideline records that limonene and linalool hydroperoxides “have recently been found to be more common in the younger age groups”. That is covered in the fragrance allergy cluster.

Lanolin is on the monograph list and also has a genuine contact allergy record. Both things are true and a page that gives only one of them is not being straight with you.

Preservatives are necessary and occasionally the problem. Phenoxyethanol is a rare sensitiser and is the usual choice; the formaldehyde releasers and isothiazolinones are the ones with worse records.

Unfragranced is not fragrance-free. A product can be unscented and contain a masking fragrance to cover a raw material smell.

What to do when something flares

Change one thing and wait. Skin is slow, and a routine overhauled in a week produces no information about what caused anything.

Keep the product that caused it. The ingredient list of a product that reliably causes trouble is the single most useful document you can bring to a dermatologist, and it is what patch testing is designed around.

Patch testing is the actual answer to “what am I reacting to”, and it is arranged through a doctor. No app and no ingredient list can do it, which is worth saying plainly on a page about ingredient lists.