Posted by Katarina Fajfar
on March 18, 2025
We usually pay a lot of attention to protecting our face and body, but what about our hair, which is also exposed to the sun's rays? Are you familiar with the term photoaging of hair? Can you name 5 products for protecting hair from the sun?
In today's blog, we will describe why it is important to protect your hair and scalp, and the easiest way to do so.
Hair structure
Hair is composed of cortex, cuticle and medulla. The cortex accounts for 90% of the total weight of the hair. This layer gives the hair its flexibility, strength, elasticity and colour. Hair is mainly made of keratin (85%), lipids and other molecules such as melanin (pigment).
How does UV light damage hair?
The fact that more than half of the female population uses hair dyes is not surprising. Such hair is chemically damaged, and at the same time exposed to external factors such as UV radiation and cigarette smoke. What are the consequences?
UVB radiation affects all layers of the hair, but its intensity decreases as you go through the layers. If the hair is damaged (dyeing or bleaching), this radiation can reach the cortex itself, where it can cause structural changes. UVA radiation, on the other hand, penetrates deeper, all the way to the cortex.
Hair photoaging
The most important consequence of UV radiation is a decrease in the mechanical strength of hair fibers due to the breaking of the bonds between the fibers (disulfide bond) and the degradation of proteins. There is also the formation of reactive oxygen species (mainly due to UVA light). As a result, the hair becomes more porous and the hair fibers become less strong. Therefore, the hair breaks faster and is rougher, the ends are split and the hair looks lifeless and not shiny.
Pigments protect the hair
There are two types of melanin pigment, eumelanin and pheomelanin. Both protect us from the effects of UV radiation, but eumelanin is more stable and provides more protection. Gray hair is more susceptible to damage because it no longer has the pigments to protect it.
Which substances, in combination with UV filters, protect our hair?
- Plant extracts have an antioxidant role (ginkgo, camellia, grapevine, acai, artichoke, pomegranate, rice, etc.)
- Vitamins have an antioxidant effect and prevent or slow down photodamage (beta carotene, retinyl pamidate, tocopheryl acetate, etc.)
- Silicones form a film on the hair and help restore damaged areas of the hair.
- Amino acids help increase fiber resistance (hydrolyzed vegetable proteins)
UV filters
In principle, similar filters are used for hair protection products against UV light as for skin protection, but they do not form a film and do not remain on the hair. So, if the shampoo contains UV filters, they are washed off with the shampoo, but they remain on the hair a little longer if the UV filters are in a spray or in a conditioner that is left on the hair for a longer time, and thus the filters have a greater chance of adhering to the hair. However, today, filters that adhere to the hair and can consequently protect it for a longer time are mostly used (cinnamidopropyltrimonium chloride, dimethylpabamidopropyl lauridimonium tosylate).
What about dietary supplements?
Stress, poor diet, sun, cigarette smoke are just some of the factors that can have a very bad effect on our hair. In addition to hair breakage and split ends, excessive hair loss or even baldness can occur, and the hair is thinner. Many people therefore use nutritional supplements to make their hair stronger, healthier and less prone to falling out, but care must be taken, as excessive doses can have the opposite effect. The picture below shows the daily permissible doses of micronutrients that can have a positive effect on our hair.
But how does UV radiation affect our scalp?
Many changes on the scalp are associated with UV radiation. Some of these are actinic keratosis, lupus erythematosus, red scalp syndrome, as well as exacerbation of atopic or seborrheic dermatitis. Most often, the changes are described as itching, burning, sometimes inflammation, or constant burning on the scalp.
How to protect the scalp?
Sunscreens are widely available and provide good protection for the skin, but their use on the scalp is unpopular, unless we have completely bald areas. However, hats are still the best way to protect our scalp, although some people are not fans of hats.
Overall, very few studies have been done to prove adequate sun protection for the scalp, so there is still a lot of room for research and possibly new products on the market.
SPF for hair?
We cannot use SPF to protect our hair, but the term HPF is used, which stands for Hair Protection Factor. It is measured as the difference in the mechanical properties of hair that is protected compared to that which is not, i.e. flexibility, breakage, etc.
Leite MGA, Maia Campos PMBG. Photoprotective Effects of a Multifunctional Hair Care Formulation Containing Botanical Extracts, Vitamins, and UV Filters. Photochemistry and Photobiology. 2018
Tr ü eb RM. Effect of Ultraviolet Radiation, Smoking and Nutrition on Hair. Current Problems in Dermatology. 2015;47:107–120.
Dario MF, Baby AR, Velasco MVR. Effects of solar radiation on hair and photoprotection. Journal of Photochemistry and Photobiology B: Biology. 2015;153:240–246