Homemade sunscreen: an ecological alternative without health risks?

Following the growing interest in natural products and homemade preparations, more people are turning to homemade sunscreens. Concern over controversial ingredients found in conventional sun care leads them to avoid certain chemical filters, such as the benzyl salicylate, the homosalate or the octocrylene, suspected of harming human health and the environment. Ecological concerns drive this trend: making one’s own sunscreen aligns with environmental responsibility as it avoids filters harmful to marine ecosystems and reduces packaging. Many Do It Yourself (DIY) blogs and social media posts help publicise these recipes by noting their natural origin, low cost and simplicity of preparation.

Most DIY sunscreen recipes rely on plant oils to which photoprotective properties are attributed. However, although some plant oils do absorb UVA and UVB radiation, this is not sufficient to provide adequate protection, as shown in the table below, indicating the SPFs of several plant oils measured in a in vitro study in 2016. Sunscreen is considered to provide low protection at SPF 4 or more, medium protection at SPF 15, and high to very high protection above SPF 30.

The overall SPF of a homemade sunscreen is not obtained by adding the SPFs of its ingredients.

It is tempting to assume that adding olive oil, coconut oil and castor oil to a product will yield an SPF above 20. However, this is incorrect. Sunscreen protection depends not only on ingredient quality but also on concentration, the ratio of actives and stability over time. These factors are essential to ensure uniform and effective protection across the skin surface. Moreover, some homemade sunscreen recipes use mineral filters, notably zinc oxide, a raw material that is easy to source. Zinc oxide is an effective UV filter when used at a precise concentration and requires correct dispersion in the formulation, a factor that professional formulators can guarantee.

Finally, users of conventional sunscreens can be confident that these criteria are met because the products are subjected to rigorous control before being placed on the market through laboratory tests and in vivo which assess the product’s actual ability to protect against UV radiation, its water resistance, photostability, and performance under various conditions. These tests are not carried out on homemade sunscreens: their SPF is thus unpredictable and lower than expected. Therefore, despite their appeal and environmental advantages, homemade sunscreens cannot provide adequate UV protection.

Making your own sunscreen is strongly discouraged by dermatologists and public health authorities. Sun protection must not be taken lightly: according to Santé publique France, more than 85% of skin cancers are directly linked to excessive UV exposure. Using an effective sunscreen is not simply a trend; it is primarily a way to preserve your skin’s health.

• CHAUHAN A. & al. UV-blocking potential of oils and juices. International Journal of Cosmetic Science (2016).

• MERTEN J. W. & al. Pinterest homemade sunscreens: a recipe for sunburn. Health Communication (2019).

• KANELLIS V. G. & al. Sharing recipes and creating potentially dangerous homemade sunscreens. Australasian Journal of Dermatology (2020).

• LIDAN X. & al. Natural components in sunscreens: Topical formulations with sun protection factor (SPF). Biomedicine & Pharmacotherapy (2021).

• ALMEIDA I. F. & al. UV filters: challenges and prospects. Pharmaceuticals (2022).