Phytocannabinoids on the skin: a transforming field

RDC 1,015/2026 brought an important change for dermatology: it began to contemplate the dermatological route for manufactured Cannabis products intended for medicinal use, within the conditions established by the Agência Nacional de Vigilância Sanitária (Anvisa). This change opens up new perspectives for the development of products applied to the skin. It is important to emphasize that the resolution deals with Cannabis products for medicinal purposes and does not represent an authorization for their indiscriminate use in cosmetics.

Outside Brazil, the topical use of phytocannabinoids is also part of this discussion. In the United States, for example, ingredients derived from Cannabis can be included in cosmetic formulations, provided they comply with applicable regulatory requirements. However, marketing them as cosmetics is not equivalent to approval as a treatment for dermatological diseases.

Compounding pharmacies are also part of this discussion, especially given the growing interest in individualized formulations based on phytocannabinoids. The ability to develop preparations with different concentrations, active ingredient combinations, and pharmaceutical vehicles represents a significant field for dermatology. However, the compounding of Cannabis-derived products must comply with specific sanitary requirements and applicable regulatory limits, and should not be confused with the authorization granted to manufactured products.

The interest in phytocannabinoids in dermatological practice

For those who treat people with skin diseases, this discussion has a face and a story. There is the itching that disrupts sleep, the pain that limits daily life, the bothersome blemishes, and the hair loss that affects one's identity. It was at the intersection between the questions of science and the needs of patients that my interest in phytocannabinoids was born. In this text, I address exclusively topical use applied to the skin and scalp.

In my clinical practice, I have observed favorable responses when combining topical phytocannabinoids with dermatological treatments. I mainly use cannabidiol, CBD, and cannabigerol, CBG, and, in selected situations, also tetrahydrocannabinol, THC.

These observations include patients with psoriasis, atopic dermatitis, vitiligo, rosacea, melasma, and various conditions related to hair loss, including alopecia areata. I also follow their use associated with the care of skin aging changes, including photoaging. My clinical impression is that they contribute to optimizing outcomes in some patients, within individualized and combined treatments.

A memorable case occurred at an outpatient teaching clinic in dermatology, where I work as a professor. An elderly patient with postherpetic neuralgia had limitations regarding the use of oral analgesics and was already taking multiple medications. This pain, which can persist after herpes zoster, compromised his well-being. In this context, topical CBD and THC were incorporated into the treatment, and I observed an excellent individual response in pain control. This experience reinforced my interest in investigating care options for patients with limited therapeutic choices.

The skin's endocannabinoid system

Scientific interest in these compounds has an important biological basis. The skin has its own functional endocannabinoid system. In addition to expressing cannabinoid receptors, especially CB1 and CB2, its cells are capable of synthesizing and metabolizing endocannabinoids, such as anandamide (AEA) and 2-arachidonoylglycerol (2-AG). This system is present in different cutaneous structures, including the epidermis, hair follicles, sebaceous glands, and nerve endings.

The cutaneous endocannabinoid system participates in regulating fundamental processes such as cell proliferation and differentiation, inflammatory response, barrier function, sebaceous activity, and hair follicle physiology. The skin, therefore, is not only a tissue that responds to cannabinoids, but also an organ that produces its own endocannabinoid mediators and possesses enzymatic mechanisms to regulate their activity. This complex signaling network contributes to maintaining skin homeostasis and provides a relevant biological rationale for investigating the dermatological potential of phytocannabinoids.

What clinical research says

Clinical research is also part of this journey. In psoriasis, a randomized, placebo-controlled study evaluating a topical CBD-based treatment was published.

On the scalp, an investigation with 50 individuals with psoriasis or seborrheic dermatitis evaluated a shampoo containing CBD and other ingredients, reporting improvement in inflammation-related parameters. The study had no comparator group and evaluated inflammatory scalp conditions, without establishing a specific outcome regarding hair loss.

Biological mechanisms, research, and clinical observations help build this field, but their results must be interpreted according to the product, indication, associated treatments, and design of each study. My observations have not yet been evaluated by me in a clinical study and do not allow attributing improvement exclusively to phytocannabinoids, nor generalizing the findings to all patients.

It is this perspective that I consider important to share with my students: observe carefully, record responses, and transform clinical experience into questions capable of guiding new research.

Formulation and absorption: what happens in the skin?

There is also a question that goes beyond the name of the ingredient: how much of it reaches the area where we intend to achieve an effect?

Penetrating the skin layers and traversing it into the bloodstream are different processes. In topical use, we seek a local action. In transdermal administration, the goal is passage through the skin to produce systemic exposure. This distinction helps explain why products applied to the skin can behave so differently.

In experimental research with human skin, increasing the concentration of CBD from 5% to 10% did not significantly increase the amount of CBD delivered to the skin under the evaluated conditions. Altering components of the vehicle, on the other hand, modified its delivery. The percentage of the ingredient alone, therefore, does not describe the performance of a product.

It also matters how the active ingredient is present: dissolved or associated with particles and delivery systems. The size of these particles is only one of the relevant characteristics. We need to understand how the compound is released, how much remains in the different layers of the skin, and how much manages to cross it. There is no single absorption percentage that describes all products.

The same caution applies to the word “nano.” It describes a technological characteristic, but it does not serve as a seal of superiority. What matters is the demonstrated performance of the product, the region it reaches, and its safety. Advanced delivery technologies for active ingredients, including nanotechnological systems, require specific pharmacotechnical and regulatory evaluation, not being automatically covered by simplified sanitary authorization pathways.

From clinical experience to research

What I see in the clinic fuels my scientific curiosity. When a patient improves, I want to understand what contributed to that response, under what conditions it occurred, and whether it could be replicated in others.

I see the advancement of topical phytocannabinoids as an opportunity to bridge patient care, research, and product development. Regulatory evolution makes room for this conversation, and patient follow-up helps identify the questions that deserve investigation.

This is the knowledge I want to help build: attentive to each patient's experience, consistent in its methods, and capable of expanding our care possibilities.

References

AGÊNCIA NACIONAL DE VIGILÂNCIA SANITÁRIA (ANVISA). Resolução da Diretoria Colegiada nº 1.015, de 2 de fevereiro de 2026. Brasília: Anvisa, 2026.

AGÊNCIA NACIONAL DE VIGILÂNCIA SANITÁRIA (ANVISA). Perguntas e respostas sobre a autorização sanitária de produtos de Cannabis, RDC nº 1.015/2026. Brasília: Anvisa, 2026.

U.S. FOOD AND DRUG ADMINISTRATION (FDA). FDA Regulation of Cannabis and Cannabis-Derived Products, Including Cannabidiol (CBD). Silver Spring: FDA.

STÄNDER, S.; SCHMELZ, M.; METZE, D.; LUGER, T.; RUKWIED, R. Distribution of cannabinoid receptor 1 (CB1) and 2 (CB2) on sensory nerve fibers and adnexal structures in human skin. Journal of Dermatological Science. 2005;38(3):177–188. DOI: 10.1016/j.jdermsci.2005.01.007.

BÍRÓ, T.; TÓTH, B. I.; HASKÓ, G.; PAUS, R.; PACHER, P. The endocannabinoid system of the skin in health and disease: novel perspectives and therapeutic opportunities. Trends in Pharmacological Sciences. 2009;30(8):411–420. DOI: 10.1016/j.tips.2009.05.004.

PUARATANAARUNKON, T. et al. Topical cannabidiol-based treatment for psoriasis: A dual-centre randomized placebo-controlled study. Journal of the European Academy of Dermatology and Venereology. 2022;36(9)–e720. DOI: 10.1111/jdv.18215.

VINCENZI, C.; TOSTI, A. Efficacy and Tolerability of a Shampoo Containing Broad-Spectrum Cannabidiol in the Treatment of Scalp Inflammation in Patients with Mild to Moderate Scalp Psoriasis or Seborrheic Dermatitis. Skin Appendage Disorders. 2020;6(6):355–361. DOI: 10.1159/000510896.

JUNAID, M. S. A.; TIJANI, A. O.; PURI, A.; BANGA, A. K. In vitro percutaneous absorption studies of cannabidiol using human skin: Exploring the effect of drug concentration, chemical enhancers, and essential oils. International Journal of Pharmaceutics. 2022;616:121540. DOI: 10.1016/j.ijpharm.2022.121540.