Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Propanediol is a good solvent, emollient and humectant. It helps to moisturize the skin and prevent moisture loss. In haircare products, it conditions hair and improves absorption of the product.
Betaine is used a lot in “organic” skincare products. It is a good moisturizer that not only hydrates the skin but also strengthens the cell membrane. This helps to lower the water loss over time. It also softens the skin and reduces irritation and redness. It’s often used at a 3-5% concentration depending on the product.
Sodium PCA is a nice moisturizer and skin softener. It contains amino acids and Sodium Hyaluronate. It’s part of the Natural Moisturizing Factor (NMF) that is responsible for keeping the outer layer of the skin hydrated. If you don’t have enough NMF you can face dryness even if you don’t have other skin problems.
Panthenol is a proud member of a league of the best-performing components. It's a stable form of Vitamin B5 and is also known as Pro-Vitamin B5. It’s a very good and effective component for hydration, healing, and soothing irritated skin. It works so soft and gentle that it’s even recommended for people with skin problems like eczema.
In haircare products it’s used for protecting the fiber. It’s researched very well and doesn’t have any negative side effects.