Oleic Acid

Oleic acid is a fatty acid, meaning that it is an acid with a long, oil-soluble tail. Oleic acid is an omega-9 monounsaturated fatty acid, which sounds like a mouthful, so let’s break it down.

‘Omega-9 monounsaturated’ just means that the long, oil-soluble tail contains one double bond (called unsaturated because it is missing some hydrogen atoms). The position of this double bond is calculated from the end of the oil-soluble tail, marked omega, and, in oleic acid, the double bonds start at the carbon atom number 9 from the omega end.

Oleic acid in skincare products helps to maintain skin structure. It is necessary for the barrier function of the skin, prevents transepidermal water loss, and is moisturizing (occlusive) and emollient.

Oleic acid feels a bit oilier and heavier on the skin than its polyunsaturated counterparts – linoleic and linolenic acid – which is why it is more suitable for dry skin (because it is more occlusive).

It is also used as an emulsifier, helping to mix oil and water in skincare products. Especially when turned into a simple salt, it is commonly added to soaps and other detergents (sodium oleate and potassium oleate are often used for their detergent properties). Pure oleic acid smells a bit like lard, so its scent is usually covered by other fragrant ingredients.

Oleic acid is one of the most common fatty acids found in nature and you can certainly find it in most vegetable oils (e.g., olive oil). Aside from skincare, monounsaturated fatty acids are also important for cardiovascular health and are preferred to fully saturated fats.

If you pay attention to your diet and stick to unsaturated fats, then you may be able to fix your blood lipid levels and lower your risk of cardiovascular issues later in life. Your skin will surely thank you as well.

Oleic acid is listed among common comedogenic ingredients by acne.org.