Midi Estriol + Face Cream

The only catch is that HA isn't a single thing; it actually comes in a wide range of molecular weights (~50 - 2,000+ kDA) and size matters.

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

This is why the best HA serums blend the two sizes together so you get the best of both worlds.

The majority of cosmetic HA is produced by bacterial fermentation, typically using Streptococcus or Bacillus strains. Typical use levels in skincare sit around 0.1-2%.

A clinical study using a 0.2% low-molecular weight HA gel showed improvement in facial seborrheic dermatitis with excellent tolerance.

These are some other common types of Hyaluronic Acid:

This makes it great for hard-to-dissolve actives like vitamin C, benzoyl peroxide, and self-tanner DHA.

It also has mild humectant and penetration enhancer abilities so it can help some actives absorb a little deeper.

The penetration boost is backed by lab research: studies using human skin samples found it improved how well an active dissolves into the upper layer of skin rather than tearing down your skin barrier. Reviews of its mechanism also describe it interacting gently with the lipids and water in your outermost layer of skin.

Just know this penetration-enhancing effect is not universal. It helps a lot in some formulas and did very little in others (so the benefit really depends on the specific product).

Safety-wise, the evidence is reassuring. The Cosmetic Ingredient Review Expert Panel reviewed it and concluded it's safe for use in cosmetics and recognized it as non-irritating, non-sensitizing, and non-comedogenic in skincare.

Typical leave-on skincare usage lands around 1-10%. The EU has sets caps of 2.6% in non-spray products, 10% in rinse-offs, 7% in oxidative hair dye, and 5% in non-oxidative hair dye.