Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Centella Asiatica Extract (Centella) is derived from an herb native to Southeast Asia. It is famous for its anti-inflammatory and soothing properties.

Centella is rich in antioxidants and amino acids, such as Madecassic Acid and Asiaticoside.

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.

Glyceryl Stearate is a mix of glycerin and stearic acid.

It is used to stabilize the mixing of water and oil ingredients. By preventing these ingredients from separating, it can help elongate shelf life. It can also help thicken the product's texture.

Madecassic Acid is a major component of Centella Asiatica Extract. It has anti-inflammatory and antioxidant properties.

It is a triterpenoid, meaning it naturally acts as an antioxidant. Antioxidants protect your skin against damage from environmental factors such as pollution and UV.

Madecassoside comes from the super popular skin-soothing ingredient, Centella asiatica. It is one of four active compounds found in the extract of Centella Asiatica.

Madecassoside has antioxidant, anti-inflammatory, and hydrating properties. It contains fatty acids, amino acids, beta-carotene, and phytochemicals.

Potassium Cocoyl Glycinate is an amino acid-based surfactant and cleaning agent. This ingredient can be derived from animals or plants. It may also be synthetically created from fatty acids of the coconut and glycine.

Potassium Cocoyl Glycinate is a gentle surfactant. Surfactants help gather the dirt, oil, and other pollutants from your skin to be rinsed away. It is a mild cleanser and naturally produces foam.

Potassium hydroxide is commonly known as caustic potash. It is used to fix the pH of a product or as a cleaning agent in soap. In cleansers, it is used for the saponification of oils.

Sapnification is the process of creating fatty acid metal salts from triglycerides and a strong base. During this process, Potassium Hydroxide is used up and is not present in the final product.

Salicylic Acid (also known as beta hydroxy acid or BHA) is a well-known ingredient for treating skin that struggles with acne and clogged pores. It exfoliates both the skin's surface and deep within the pores to help clear out buildup, control oil, and reduce inflammation.

Unlike AHAs (alpha hydroxy acids), salicylic acid is oil-soluble. This allows it to penetrate into pores which makes it especially effective for treating blackheads and preventing future breakouts.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.