How to deal with the painful return of sunburn (and their consequences)

2023-08-07 06:47:36

« Under the sun, [s]expose a little more to the sun… “, as Jenifer’s song says… You have been dreaming about it for months. Be careful though: your skin could make you pay dearly if you bask too long. Tense, scarlet, stinging – these are the painful signs that you’ve caught a sunburn!

It is now widely accepted that overexposure to the sun, beyond small allergies and the frequent painful and unsightly sunburn, can have serious consequences on our health in the more or less long term.

To better understand these consequences, let’s dwell for a moment on the two protagonists of our problem: the skin and the UV rays of the sun.

The skin: a barrier put to the test…

It is often neglected and yet the skin is the largest organ of the human body and our best ally to protect us from external aggressions.

It is composed of three layers: the epidermis, the dermis and the hypodermis (from the outside to the inside of our body). The epidermis, made up of several layers of keratinocytes (skin cells), is its outer envelope. It is a fabric in permanent renewal which constitutes the first rampart against external aggressions, such as UV radiation.

The dermis, on the other hand, is a vascularized tissue that gives resistance and elasticity to the skin via collagen and elastin fibers, produced by cells called fibroblasts. In addition, immune cells are present in the vessels and provide a second line of defense after the epidermis.

Despite this well-organized defence, overexposure to the sun puts the skin to the test.

The effects of the Sun…

Sunlight contains different types of ultraviolet (UV) rays characterized by their wavelength – which determine their ability to penetrate the skin (UV radiation penetrates the skin more easily the higher the wavelength ): UV-A, UV-B and UV-C (from longest to shortest wavelength).

When these rays pass through the atmosphere, all UV-C and most UV-B are absorbed by the ozone layer. Only UV-A is not filtered out as efficiently: it represents 95% of the UV that reaches the earth’s surface.

UVA rays penetrate to the dermis. They have a long-term effect and play a major role in the early aging of the skin and increase the risk of skin cancer.

UVB rays reach the epidermis and have the effect, in the short term, of the appearance of sunburn and tanning. Nevertheless, the accumulation of their action plays a role in early skin aging and the appearance of cancers in the longer term.

The Sunburn!

Let’s go back to one of the earliest manifestations of overexposure to UV radiation: the famous sunburn.

This is due, in large part, to UVB rays which damage micro-RNAs (molecules resulting from the transcription of DNA which intervene in the regulation of gene expression), present in the cells of the epidermis, the keratinocytes. The body reacts by launching an inflammatory reaction which results, in particular, in an increase in blood flow towards the damaged area, hence the reddening of the skin (erythema).

This inflammatory process allows the body to get rid of degraded cells before they become cancerous. The damaged cells sacrifice themselves to save our skin (this is apoptosis, or programmed cell death), and the skin peels off! Thus, sunburn is a short-term protective reaction.

To peel means that one has been burned. Re-exposing weakened, healing skin is a bad idea – Fokke Baarssen / Shutterstock

There are several degrees of severity of sunburn:

The lightest is the tan which, in itself, already constitutes a defense reaction of the skin against UV aggression.
After this stage, it is the sunburn, a burn that reaches the epidermis and can be more or less serious. A first-degree burn results in the appearance of a bright red, painful erythema. It disappears after a few days and the skin may peel off as it heals.
When blisters appear, the damage is more severe and we speak of superficial second degree burns. Healing lasts about two weeks but leaves no visible sequelae.
The stage above corresponds to the deep second degree burn. In this more serious case, the superficial dermis is affected (in addition to the epidermis), blisters appear and blood vessels are destroyed. It takes several weeks to heal and this type of burn leaves traces.

Even if most sunburns correspond to first degree burns which disappear in a few days, the damage persists! Indeed, whatever their intensity, sunburn can have consequences for our skin and our health in the longer term…

Always protect yourself

Unfortunately, in the long term, exposure to UV rays can lead to photo-aging and the appearance of cancers.

The major effects of photoaging are at the level of the dermis. Indeed, UVA rays are responsible for the formation of free radicals (very reactive oxygen molecules) which attack the fibroblasts, thus degrading the production of collagen and elastin fibers which give resistance and elasticity to the skin. skin. This is called “oxidative stress”, the main cause of premature aging: the skin loses its elasticity and more or less deep wrinkles appear.

Worse still, in 2009, the IARC classified UVA and UVB rays as proven carcinogens for humans. Indeed, if damaged keratinocytes (with unrepaired DNA) are not eliminated by apoptosis, skin cancer can develop. Two types of cancer can be distinguished: cutaneous carcinomas, the most frequent, and melanomas, the most dangerous.

So one watchword: protect yourself! When it comes to the sun, prevention is better than cure: use sun protection products, avoid exposing yourself to the hottest hours (summer between noon and 4 p.m. in France)… And these recommendations are valid for everyone, even for people with dark skin, because not getting sunburn does not prevent skin cancer.