CBD for hair: what 4 studies actually say
Most research on CBD and the scalp was done in the lab: CBD lowers sebum production in cultured cells and, at high concentration, slows the growth of isolated hair follicles. The only published human data is a series of 35 cases with no control group. A CBD cosmetic therefore cannot claim to stop hair loss or regrow hair, because the law requires evidence these studies do not provide.
Key takeaways
- The human hair follicle has its own endocannabinoid system, where activating the CB1 receptor slows growth.
- CBD lowers lipid production in human sebaceous cells, which explains the interest for oily scalps.
- Only one human regrowth study exists, on 35 people, without placebo or blinding.
- Hemp seed oil, a frequent ingredient in these products, holds more than 70% polyunsaturated fatty acids and almost no CBD.
- Every cosmetic claim needs substantiation, and a product presented as curing a disease is legally a medicine.
Four studies, four levels of evidence
The endocannabinoid system groups receptors (CB1, CB2) and the molecules the body makes to activate them, such as anandamide. It is found in the skin and in the follicle, the small pocket each hair grows from. Four papers are cited whenever CBD and hair come up, and their weight varies a great deal.
| Study | What was tested | Result |
|---|---|---|
| Telek et al., 2007 | Human follicles in culture, THC and anandamide | Growth slows, through the CB1 receptor |
| Oláh et al., 2014 | Human sebocytes in culture, CBD | Less lipid produced, less proliferation |
| Szabó et al., 2020 | Human follicles in culture, CBD at several concentrations | Anti-inflammatory at low dose, growth slowed at high dose |
| Smith and Satino, 2021 | 35 adults with androgenetic alopecia, no control group | More hairs counted after 6 months |
In the lab: sebum and follicles
Three of the four come from the University of Debrecen, in Hungary. In 2007, Telek and colleagues worked on human follicles removed and kept alive in culture. Anandamide and THC slowed the lengthening of the hair shaft and pushed the follicle early into its regression phase, called catagen. The effect vanished once the CB1 receptor was blocked, so the follicle makes its own signals to slow its growth.
In 2014, the same team published in the Journal of Clinical Investigation a study on sebocytes, the cells of the sebaceous glands. Acting through the TRPV4 channel, CBD reduced both lipid production and the multiplication of these cells, and it showed an anti-inflammatory action. The authors were studying acne, and the scalp was outside their scope. These results are covered in our article on CBD and sebum.
In 2020, Szabó and colleagues applied CBD to follicles in culture. Below one micromolar it had an anti-inflammatory effect, and at micromolar concentrations it slowed growth. More CBD therefore does not give more hair, and none of these lab concentrations converts directly into a shampoo dose.
In humans: a series of 35 cases
Clinical data comes down to one case series published in 2021 in the journal Cannabis. In their own practice, its two authors followed 28 men and 7 women with androgenetic alopecia, the hormonal and genetic form of hair loss. Each applied a hemp flower extract once a day for six months, which delivered about 3 to 4 mg of CBD. In the men, the average hair count in the monitored area rose from 18.3 to 33.2.
No conclusion can be drawn from it. Every participant received the extract and knew it, with no placebo group and no blinding. The sample is small, and no other team has repeated the work. The authors also report that a third of the patients lost slightly more hair in the first month.
Hemp oil and CBD: two different ingredients
The main ingredient of many "hemp" hair products is hemp seed oil, listed as Cannabis Sativa Seed Oil in the INCI ingredient list. Pressed from the seeds, it holds almost no cannabinoids. Its cosmetic interest lies in its lipids: a comparative analysis published in 2022 found over 70% polyunsaturated fatty acids, with a large share of omega-3. Cosmetics use these lipids mostly to nourish the hair fibre and reduce dryness.
CBD comes from the flowers and leaves, and is listed as Cannabidiol or under the name of a plant extract. When the INCI list mentions seed oil alone, the product delivers no meaningful amount of CBD. How to read these names is shown in our article on CBD massage oil.
What a CBD cosmetic can promise
Regulation (EC) No 1223/2009 defines a cosmetic by its functions: cleaning, perfuming, changing the appearance, protecting and keeping in good condition. Its Article 20 forbids attributing to a cosmetic characteristics or functions it lacks. Regulation (EU) No 655/2013 adds six common criteria, one of them evidential support: every claim must rest on adequate and verifiable evidence.
In practice, this means two things:
- promising regrowth or an end to hair loss on the strength of CBD is unsupported, because the only human study had no control group;
- a product presented as curing alopecia enters the scope of medicines. Article L5111-1 of the French Public Health Code defines a medicine as any substance "presented as having curative or preventive properties with regard to human diseases".
A CBD product may claim what its formula demonstrates, such as cleaning, nourishing the fibre or comfort. Our guide to authorised claims for CBD cosmetics goes through the six criteria, and the guide on fragrance allergens helps you read the rest of the label.
See a dermatologist if hair loss is sudden, comes in patches or lasts several months: its hormonal, nutritional or autoimmune causes can be diagnosed. If you face a hair drug test, our article on what hair reveals in drug testing explains what these tests look for.
Frequently asked questions
No controlled study has shown it. A series of 35 cases found more hairs after six months of application, with no placebo group for comparison. In the lab, CBD at high concentration actually slows follicle growth.
It reduces lipid production in cultured sebaceous cells, but no trial has measured this effect on a human scalp. A product may claim an effect on oiliness only after demonstrating it for its own formula.
Almost none. Hemp seed oil is rich in fatty acids and poor in cannabinoids. CBD comes from the flowers and leaves, and the ingredient list names it separately.
Nothing in the data supports it. A cosmetic promising that CBD will stop hair loss makes a claim without sufficient evidence, and a product claiming to cure alopecia comes under medicines law.
Written by the Phytogrammes team
Each journal article draws on cited primary sources: ANSM, EFSA, EUR-Lex and peer-reviewed publications. Product profiles are distinguished from documented laboratory results. Our approach.
Article published on . CBD is not a medicine.