Are there dangers associated with the topical use of caffeine?

Naturally present in plant constituents such as coffee seeds, tea leaves (theine), guarana berries (guaranine), yerba mate leaves (mateine), kola nuts or cocoa beans, the caffeine is a chemical compound that is gaining interest for cosmetic formulations. Antioxidant, stimulating, draining, lipolytic, soothing... it is incorporated into the formulation of many cosmetics to improve the appearance of the skin and the condition of the hair.

What also contributes to its success is its harmlessness. To date, caffeine is considered well tolerated by all skin types in skincare, even though rare cases of urticaria and allergy reactions have been recorded. Non-irritating, non-allergenic and non-sensitising, caffeine belongs to the category of products generally recognised as safe (GRAS). It is also not classified as a CMR substance according to Regulation (EC) 1272/2008.

Are there precautions to be taken?

• Bioavailability: For cosmetic use, the ability of caffeine to influence various processes occurring in the skin depends on its ability to penetrate through the skin barrier. A study revealed that after 24 hours, the highest concentration of applied caffeine was located in the epidermis and only a small amount of the alkaloid was detected in the dermis. However, the type of galenic preparation of the skincare product influences the diffusion profile of caffeine through the skin. An increase in the permeability of caffeine was observed in water-in-oil nano-emulsion formulations compared to aqueous solutions of caffeine. Moreover, for caffeine to reach the target tissues, it can be carried either by alcohol, which promotes penetration, or by permeation promoters (e.g. niacinamide, oils, glycols, etc...), which increase the solubility of caffeine and facilitate its permeation through the skin, or encapsulated in liposomes, microspheres that deliver the active ingredients to their target.

• Dosage: Contrary to what one might think, caffeine is not subject to a usage limit in the European cosmetic regulation. However, it is recommended to not exceed 5% of the final mixture for a skin application and to always use it diluted. Beyond this dosage, caffeine can irritate the skin and present risks of allergy symptoms appearing: redness, irritation, itching...

• Efficacy: For a notable lipolytic action , it is important to ensure that the skincare product contains between 2 and 5% caffeine in its formula. At a concentration below this, the product will be less effective.

• Tolerance: Before incorporating a new ceramide-based skincare product into your routine, we recommend you carry out a tolerance test. This is done by applying a small amount of the product to the inside of your elbow, behind your ear, or on the inner side of your wrist. If you do not notice any adverse reaction within the next 24 hours, you can use the product.