Can the sun improve the signs of keratosis pilaris?

It is true that individuals affected by keratosis pilaris generally notice an improvement in their symptoms during the summer. Several factors can explain this phenomenon, among which is the tanning induced by the sun. Indeed, upon penetrating the epidermis, UV rays trigger several biological reactions including the binding of the melanotropic hormone (MSH) to the melanocortin 1 receptor (MCR1), located on the membranes of melanocytes. This binding triggers a cascade of reactions, resulting in the synthesis of melanin, the brown pigment responsible for skin colouration. To a certain extent, this can camouflage imperfections and help to make the rough bumps of keratosis pilaris less visible.

Furthermore, in defence against UV rays, the epidermis also tends to thicken. This thickening of the stratum corneum is a result of a rapid differentiation of keratinocytes under the influence of UV, leading to an intensification of the keratinisation of the epidermis. This is an adaptive response, a thicker skin having a better capacity to dissipate ultraviolet rays, which reduces damage to deeper cellular components. This thickening has the effect of masking small bumps associated with keratosis pilaris.

Even though the sun may temporarily help to reduce the signs of keratosis pilaris, it is important to remember that UV rays have a detrimental effect on the skin in the long term.

In a manner akin to acne, the effects of the sun on keratosis pilaris only last for a season. As summer draws to a close and the sun shines less brightly in the sky, the epidermis thins out to regain its initial thickness. The follicular plugs associated with keratosis pilaris then become clearly visible again and the skin resumes its rough texture.

Furthermore, UV rays are responsible for significant cellular damage and cause redness, even sunburns of varying degrees of pain. If we add to this an increased risk of skin cancer, deeper wrinkles and other harmful effects, it becomes clear that it is better to avoid excessive sun exposure and to always apply sun protection in sufficient quantity. There are other solutions, safer ones, to alleviate the symptoms of keratosis pilaris.