What is stearic acid for?

Have you ever read the ingredient deck on a bottle of lotion and wondered “What is stearic acid and why is it in this lotion?” You may even be wondering if you should be putting something with called "acid" on your skin at all. You’re not alone, in fact, we get questions about ingredients every day, and stearic acid is one that always comes up.

Stearic Acid is a fatty acid with a long hydrocarbon chain. Fatty acids, such as stearic acid, are found in marine and freshwater organisms, bacteria, and vegetable oils and animal fats. While it is technically an acid because it has a pH of about 6, it is not at all the same as a strong, tissue dissolving acid like apple cider vinegar with a pH of 2 or hydrochloric acid with a pH of 0.  To put this into perspective, water sits at a pH of about 7, so stearic acid is slightly more acidic than water. Perfect for your skin, as your skin needs a formula to be at about 4.8-6 to work. Any higher than the 7 of water and it will be too alkaline. Any lower and it is too acidic and both ends of the spectrum can cause epidermal damage. 

Stearic Acid is used to stabilize formulations and it gives products a smooth, satiny feel making it a great ingredient choice for creams and lotions. But since it is also a fatty acid, it also helps to rebuild the skin’s barrier in a similar way as ceramides too. 

The Cosmetic Ingredient Review Expert Panel reports that topical application of stearic acid to the skin produced no toxicity. Further studies using formulations containing stearic acid at concentrations up to 13% indicate that it is neither an irritant, sensitizer nor photosensitizing agent. Good news! It won’t irritate your skin or cause it to become sensitized.

xo, Jacci & Laura

Jacci Russ

Our founder Jacci, combines her background in Marine Biology and Organic Cosmetic Science for high performance, yet clean skincare using ocean-based ingredients. She has traveled the world in search of strange spa treatments and perfect pizza. Dreamer and Doer. Adventuress, animal activist, recovering cheese addict. Read more about Jacci.