Bioavailability
Bioavailability — a measure of how much of an applied ingredient actually reaches its intended site in the skin in an active, usable form. In topical products it reflects the portion of an active that penetrates the barrier rather than staying on the surface or breaking down. It is influenced by the ingredient's chemistry, its concentration, the formula it sits in, and the condition of the skin.
Key points
- Bioavailability describes the fraction of an applied ingredient that becomes available to interact with skin cells or structures.
- Molecular size, solubility, and stability all affect how bioavailable a topical ingredient is.
- The surrounding formula, including solvents and delivery systems, can raise or lower an active's bioavailability.
- A high concentration on the label does not guarantee high bioavailability if little of the ingredient is actually absorbed.
Frequently asked
Why does bioavailability matter in skincare?
It helps explain why two products with the same listed ingredient can perform differently, since only the absorbed, active portion can produce an effect.
Can formulation improve an ingredient's bioavailability?
Yes, choices like solvents, pH, encapsulation, and delivery systems can influence how much of an active penetrates and stays stable in the skin.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
