# Can hair follicles smell? The sandalwood molecule and hair growth

In a manner of speaking, yes. Human scalp hair follicles carry an olfactory receptor, OR2AT4, and a synthetic sandalwood molecule called Sandalore activates it. In follicles kept alive in the lab, that prolonged the growth phase by reducing cell death and raising IGF-1 (Nature Communications, 2018). A 2021 trial in 60 women used a 1% leave-on solution; our conditioner rinses out.

Canonical: https://existentialcosmetics.com/guides/sandalwood-molecule-hair-growth

## What did the 2018 study find?

Olfactory receptors are not confined to the nose. In 2018, Chéret and colleagues reported in Nature Communications that the epithelium of the human hair follicle, particularly the outer root sheath, expresses OR2AT4. Stimulating that receptor with Sandalore, a synthetic sandalwood odorant that is a selective agonist for it, prolonged hair growth in organ-cultured human scalp follicles by decreasing apoptosis and increasing IGF-1. Two controls make it convincing rather than merely correlated: silencing the receptor, and blocking it with the antagonist Phenirat, both inhibited growth.

## Has it been tested on people?

Once, and cleverly. In 2021, Jimenez and colleagues ran a randomized, double-blind, placebo-controlled trial in 60 women aged 18 to 65 with telogen effluvium, the kind of diffuse shedding that follows stress or illness. Thirty women used a 1% Sandalore solution and thirty used a placebo for 24 weeks. The placebo was real sandalwood oil that smelled identical but does not activate OR2AT4, which means the trial separated the receptor from the scent. Sandalore reduced shedding and increased hair volume and the percentage of follicles in the growth phase, the latter two significantly more than placebo when calculated against baseline. Most of the anti-shedding effect appeared by week 8 and held to week 24.

## Is Sandalore real sandalwood?

No, and that is the point. It is a lab-made aroma molecule, consistent from batch to batch, which is why it could be used in the study at all. Real sandalwood oil smells the same and did nothing to the receptor in the trial. A sandalwood scent is not itself evidence of anything; the specific molecule is what activates OR2AT4.

## What does this mean for a conditioner?

Nothing, and we would rather say so plainly. The trial used a 1% leave-on solution in women with a shedding condition. Human Condition is a rinse-out conditioner for people who wash their hair, and it makes no claim about shedding or growth. Sandalore is in it as the sandalwood note of its scent, because it smells wonderful and is gentle. The research is here because it is the kind of thing we think you should get to read.

- Studied: 1% leave-on, 24 weeks, telogen effluvium.
- In our bottle: a sandalwood note in a rinse-out conditioner, no hair claim of any kind.
- True either way: your follicles have a smell receptor. Biology is excessive.

## What we made with it

Human Condition, which comes after the five face products, is a cleansing conditioner built for the scalp first: it is skin, and it deserves the gentle wash your face gets. Real conditioning from behentrimonium methosulfate and cetearyl alcohol, body from panthenol and hydrolyzed protein. Its scent, Pep Talk, uses Sandalore as its sandalwood note, and that is the reason it is in the bottle: it smells wonderful and it is the same every time. The research above is why the molecule is interesting to read about, not a claim about the conditioner.

## Related questions

**Is Sandalore a hair loss treatment?**

No. One 24-week trial in 60 women with telogen effluvium used a 1% leave-on solution and reported less shedding. That is one trial, one condition and a different product format. Nothing in a rinse-out conditioner should be read as a treatment, and if you are losing hair, see a dermatologist.

**Why put Sandalore in a conditioner at all?**

Because it smells wonderful and it is gentle. It is the sandalwood note in Pep Talk, chosen for the scent. The research on this page is background reading, not the reason it is in the bottle.

**Do other scents do the same thing?**

Not that anyone has shown. OR2AT4 is a specific receptor and Sandalore is a selective agonist for it. Real sandalwood oil, which smells the same, did not activate it in the trial and served as the placebo.

## Sources

1. Chéret J, Bertolini M, Ponce L, et al. Olfactory receptor OR2AT4 regulates human hair growth. Nat Commun 2018;9:3624. (PMID 30228264) https://pubmed.ncbi.nlm.nih.gov/30228264/
2. Jimenez F, López E, Bertolini M, et al. Topical odorant application of the specific olfactory receptor OR2AT4 agonist, Sandalore, improves telogen effluvium-associated parameters. J Cosmet Dermatol 2021. (PMID 32645251) https://pubmed.ncbi.nlm.nih.gov/32645251/