La Roche-Posay Effaclar Adapalene Gel 0.1% Topical Retinoid For Acne Versus Obagi Tretinoin 0.05% Gel

Carbomer is a polymer of acrylic acid. Its main role is to create a gel consistency.

A high amount of carbomer can cause pilling or balling up of products. Don't worry, most products contain 1% or less of carbomer.

Methylparaben is a preservative and is a paraben. It is used to prevent the growth of fungus, mold, and other harmful bacteria. Parabens are chemicals used as preservatives in both cosmetics and food.

Methylparaben can be synthetically created. It can also be found naturally in some fruits, such as blueberries.

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.