The science library
Six essential categories explained through skin biology, cosmetic chemistry, clinical guidance, and the limits of what a label can prove.
Our reference frame
“Cosmeceutical” is useful editorial shorthand for skincare positioned between cosmetic care and drug-like benefit, but it is not a legal product category in the United States. A product’s intended use and claims determine whether it is regulated as a cosmetic, a drug, or both. Read the FDA distinction.
Our foundational text is Cosmeceuticals and Cosmetic Ingredients by Leslie S. Baumann, MD (McGraw-Hill Education, first edition, 2015). We use its category and ingredient framework, then check clinical, public-health, and regulatory claims against current authoritative sources.
The book is a starting point—not a substitute for newer evidence or individual medical care. Every category page separates mechanism from finished-formula evidence, explains what to inspect on a label, and names the limits of the available evidence.
Core categories
Start with the skin problem, examine the mechanism, compare the complete formula, and add complexity only when the expected benefit justifies it.
Cleansers
A facial cleanser should remove the material you want gone—such as sunscreen, makeup, excess oil, sweat, and particles—while limiting unnecessary disruption of the stratum corneum.
Examine the scienceMoisturizers
Moisturizers are complete delivery systems, not single hero ingredients. Humectants increase water in the outer skin, occlusives slow evaporation, and emollients smooth spaces between shedding cells.
Examine the scienceSunscreens
Sunscreen reduces ultraviolet exposure on uncovered skin. Broad-spectrum performance, adequate coverage, reapplication, and a formula you can use consistently matter together.
Examine the scienceAcne care
Acne is not a cleanliness failure. Follicular plugging, sebum, inflammation, and Cutibacterium acnes interact, so different topical ingredients address different parts of the process.
Examine the scienceRetinoids
Retinol, retinaldehyde, adapalene, tretinoin, and other retinoids belong to the vitamin A family, but they are not interchangeable. Molecule, conversion, stability, vehicle, evidence, and regulatory status all matter.
Examine the scienceAntioxidant serums
Antioxidant chemistry is biologically relevant, and some topical vitamin C formulas have clinical evidence. The meaningful unit is still the finished formula: identity, stability, delivery, packaging, and use determine what reaches skin.
Examine the scienceHow to read the library
