Skin Care Products and Cosmetic Ingredients
What this domain covers
This domain tests ingredient function, product selection by skin type, label reading and safe use.
Ingredient families
- Cleansers: surfactants lift oil; foaming gels suit oily skin, cream cleansers suit dry skin, micellar water suits quick make-up removal.
- Humectants: glycerin, hyaluronic acid and urea draw water into the stratum corneum.
- Emollients and occlusives: oils, shea butter and petrolatum soften and seal.
- Exfoliants: AHAs such as glycolic and lactic acid work at the surface and increase sun sensitivity; BHA (salicylic acid) is oil-soluble and suits blackhead-prone skin; enzyme powders are gentler.
- Actives: niacinamide for oil control and barrier support, vitamin C as an antioxidant, retinol for ageing and acne (avoid in pregnancy), azelaic acid for pigmentation.
- Sunscreens: SPF against UVB, PA grade against UVA; mineral filters are zinc oxide and titanium dioxide.
Label literacy
INCI names are listed in descending order of concentration, and anything at 1% or less may appear in any order. Check the PAO symbol and the expiry date before use.
Worked example
A 22-year-old with oily, acne-prone skin asks for a night cream. Choose a light gel with niacinamide and no added fragrance rather than a rich shea-based cream. Reasoning: occlusive butters can trap sebum and worsen comedones, so the base matters more than a nourishing claim.
Traps
- Assuming natural or herbal products are hypoallergenic.
- Layering retinol with strong acids in the same routine.
- Believing SPF in a foundation is sufficient protection.