The science of azelaic acid in haircare
Hair thinning is one of the most searched beauty concerns worldwide, and the science points to the scalp. This article explains the biology behind hair loss and why azelaic acid is such an interesting active for haircare formulations.
The hair growth cycle
Every hair follicle cycles through three stages: anagen (the growth phase, where 80–90% of our hairs are at any moment), catagen (a short transition phase) and telogen (the resting phase, after which the hair sheds). Healthy hair depends on follicles spending as long as possible in the anagen phase.
The role of DHT
In the most common form of hair thinning, androgenic hair loss, the hormone dihydrotestosterone (DHT) plays the central role. DHT is produced from testosterone by the enzyme 5-α-reductase. In sensitive follicles, DHT causes progressive miniaturization: strong terminal hairs are gradually replaced by fine, barely visible vellus hairs.
Where azelaic acid comes in
Azelaic acid has been shown to inhibit 5-α-reductase activity at low concentrations, which makes it a scientifically interesting active for cosmetic haircare aimed at the appearance of fuller, healthier-looking hair. Its effect can be complemented by supporting ingredients such as zinc salts and vitamin B6, which are associated with a synergistic effect on the same pathway.
Unlike pharmaceutical options, azelaic acid is permitted in cosmetics and combines its haircare relevance with a mild profile, an attractive proposition for leave-on scalp and hair formulations. Typical use levels in hair and scalp applications are 3–10%, depending on format and positioning.
Formulation approaches
- Leave-on scalp serums and tonics (solubility supported by propanediol or butylene glycol)
- Rinse-off treatments with azelaic acid as supporting active
- Advanced delivery systems such as organogels for prolonged contact
Interested in developing haircare with azelaic acid? Read more about Azepur99® or request technical documentation.
