The real story on moisturizers

May 6, 2019 / Håvard Liltved Dalen

Here’s what hydrates dry skin:

Water.

Here’s what a moisturizer needs to contain:

Water, unless you’ve already had a soak.

An ‘occlusive’, to hold the water in. The best is white petrolatum, in use since 1872, patented as Vaseline. (Its only downside is that it’s greasy.) Other common occlusives are lanolin, mineral oil, the silicones, paraffin, cetyl alcohol, lecithin, and stearic acid.

A ‘humectant’, to pull water up from the deeper skin, and, if it’s humid out, from the air. Well known humectants include glycerin, panthenol, and honey.

Here’s what you’re actually moisturising:

‘Corneocytes’, the dead cells on the very outside of your skin, and the intercellular ‘lipid’ molecules that hold them together. About 20% of this ‘stratum corneum’ layer should consist of absorbed water, or else your skin gets cracked and flaky.

Here’s what’s nice to have in a moisturizer, even though it doesn’t moisturize anything:

An ‘emollient’. It doesn’t add water, but it makes your skin feel smooth. ‘Rubbing alcohol’ is one of these, called what it is for that reason.

Menthol. It helps with the itch that you get with dry skin.

Lactic acid. This can soften thick skin, because it acts on the lipids that hold outer skin cells together.

Lovely perfume.

Here’s what you really don’t need in a moisturizer:

Oil. Your sebaceous glands supply that. Dry skin is about water loss, anyway, not oil. The only benefit you can derive from oil is as another occlusive.

Sciency language on the label.

A big price tag.

Here’s what moisturizers don’t do:

‘Nourish your skin’. Vitamins C and E are antioxidant nutrients, but they aren’t present in big enough quantities to matter, and anyway, they lose their bioactivity when they’re exposed to light and air.

‘Reduce fine wrinkles’. Vitamin A, in the form it’s usually found in creams, hasn’t been shown to do that. Vitamin A in the form of retinoic acid might, but this is a prescription drug, and you should talk to your doctor about using it.

Be ‘hypoallergenic’. This means unlikely to cause an allergic reaction. No manufacturer would knowingly make anything else.

Be ‘non-comedogenic’. This means unlikely to encourage pimples. No manufacturer would knowingly make anything else.

Here are the moisturizers that work:

All of them.

This is the moisturizer you should buy:

The one you like.

Our dermatologists are ready to answer all of your skin questions.