A L’Oréal patent published in early 2026 outlines a topical scalp treatment designed to inhibit cortisol, the hormone associated with the body’s stress response.
The formula combines wild indigo extract, niacinamide, and caffeine. Although early laboratory findings are promising, the treatment has not yet been shown to reduce shedding or improve hair growth in people.
The Cortisol and Hair Loss Connection
L’Oréal describes cortisol as a possible contributor to hair thinning and loss.
The theory is that elevated cortisol, both throughout the body and locally in the scalp, may promote inflammation around the hair follicles. Over time, this could affect follicle health and contribute to shedding.
The patent explores whether reducing cortisol activity directly on the scalp could help support healthier hair.
What Is in the Formula?
The patented formula combines:
- Tephrosia purpurea seed extract, also known as wild indigo
- Niacinamide, or vitamin B3
- Caffeine
L’Oréal reports that wild indigo extract has previously reduced cortisol production in skin cells. In the patented formula, niacinamide and caffeine appeared to strengthen its cortisol-inhibiting effects.
What Did the Laboratory Testing Show?
Testing was performed in cell cultures rather than human participants.
Different combinations of the three ingredients produced cortisol inhibition ranging from 21% to 52%. The patent also states that the ratio of wild indigo extract to caffeine must remain at or below four to one to maintain the effect.
The formula could potentially be developed as either a rinse-off or leave-on scalp product.
What Are Experts Saying?
Independent cosmetic scientists have described the findings as interesting but preliminary.
Reducing cortisol in laboratory-grown cells does not necessarily mean the formula will reduce shedding or stimulate visible hair growth. Long-term, placebo-controlled human studies would be needed to demonstrate those benefits.
Experts have also suggested testing the treatment directly on human hair follicles and in people experiencing significant stress.
Leave-On Products May Have an Advantage
A leave-on formula may be more effective than a rinse-off product because it would remain on the scalp longer, allowing more time for ingredient delivery.
A Cosmetic or Medical Treatment?
The patent approaches the boundary between cosmetic and medical claims.
The proposed cosmetic benefit, healthier-looking hair, is linked to a biological effect involving a hormone. This distinction may influence how any future product is formulated, marketed, and regulated.
Hair Loss Has Many Causes
Cortisol is only one possible contributor to hair loss. Other factors may include:
- Genetics
- Hormonal changes
- Nutritional deficiencies
- Medical conditions
- Medications
- Illness
- Psychological stress
- Scalp inflammation
A topical cortisol-targeting treatment would not address elevated cortisol throughout the body or every underlying cause of hair loss.
What Comes Next?
The patented ingredient combination reduced cortisol activity in early laboratory testing, but it has not yet been proven to reduce shedding or improve hair growth in human clinical trials.
Whether L’Oréal develops it into a consumer product will likely depend on additional research demonstrating that the laboratory findings translate into meaningful results for the scalp and hair.
References:
- Culliney K. “Decoding Beauty Breakthroughs: L’Oréal Patent Taps Indigo + Actives to Target Cortisol for Hair Loss.” Cosmetics & Toiletries.
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