Hyaluronic acid (HA) is being used in cosmetic products as a moisture booster, preventer of moisture loss, humectant, and anti-inflammatory. It is an anionic polysaccharide that has great water binding activity that might work as an anti-wrinkle ingredient at low levels, like 0.1% to 2%.
If it doesn't penetrate through our skin, does it do it any good? Yes, it does. Studies are showing that the application of topical HA of various molecular weights can form films on the skin that will increase moisture, reduce moisture loss, speed up wound healing, reduce inflammation, and decrease the formation of age spots. It softens the skin and restores elasticity to skin, which can reduce the look of fine lines and wrinkles.
I'm using the low molecular weight or LMW hyaluronic acid from Lotioncrafter, and its recommended use is 0.01% to 2%. This post from Making Cosmetics notes that you don't want to go over 2% as it will clump because all the water is bound. And, in the research I've done, it doesn't seem like there's any point in using more than 2% as it doesn't offer more moisturizing or other benefit.
It's not an inexpensive ingredient - 10 grams will run you $15 to $25 depending on the weight - so you want to use as little as you need to get the maximum benefits. You can make up the gel from the recipe to which I've linked below, then use that gel in your products. For instance, if you wanted to use 0.1% in a product, you could add 0.1% HA into the product, or you could add 5 grams of the gel to the product. (10 grams has 0.2 grams HA, so 5 grams would have 0.1 grams HA.) Either way, you're getting 0.1% HA.
using this recipe and found it a simple recipe to make. I sprinkled in the HA, mixed well by hand, then I left it for three hours and came back to a lovely looking gel! As you can see, it is completely clear, and doesn't feel sticky on skin.
I've been testing it over the last few weeks. So far the results are pretty awesome! My mother and best friend are using it under their night time moisturizer and both feel that their skin looks plumper and smoother. I've started using it at night on its own as I don't use a moisturizer, and I feel that my skin feels moister than it did before using it.
You can use it alone in a gel format, with other ingredients in a gel format, or you could add it to things like lotions, moisturizers, or any other water containing product.
Here's a recipe from Makingcosmetics.com for a serum that includes it. Here's a recipe from Lotioncrafter that also includes Vitamin C, Vitamin E, panthenol, and more, and a simpler recipe that contains HA and panthenol! As I'm still in the process of playing with this ingredient, I don't have my own recipes to share, but I can tell you that the gel I list above from Lotioncrafter feels just awesome!
Handbook of Cosmetic Science & Technology, 3rd edition
This study (although they used human growth factor and don't indicate how much of what weight HA they used, so take it with a grain of salt)
This study, which is about reduction in facial seborrheic dermatitis
This study, which indicated it could be used for faster wound healing
Factsheet from Making Cosmetics (they had a better one that I saved on my computer)