What are the dangers of sunburn on the skin?

The sun emits heat, light, as well as UV rays. Among these UV rays, we distinguish three different types: UVA, UVB, and UVC. It is the UVB rays that cause sunburn because, due to their short wavelength, they have a low penetration into the dermis.

At the skin level, a sunburn is characterised by redness, pain with itching (pruritus) and the appearance of blisters (phlyctenes). These symptoms are the result of a inflammatory process which causes a dilation of the blood vessels and a reddening of the skin.

It is important to note that sunburn can occur without direct exposure to the sun. Indeed, UVB rays are present regardless of the weather and they are reflected by water, sand, and snow.

A sunburn can lead to various dangerous consequences for your skin, as well as for your health:

In the short term, sunburns cause varying degrees of burns depending on the type of sunburn. There are three types of sunburns:

1. First-degree sunburn : This type of sunburn is characterised by the presence of bright red and painful lesions on the surface of the epidermis and the absence of blisters. Subsequently, a more or less significant peeling is observed. The healing duration is 2 to 7 days without leaving any spots or scars provided the skin is well cared for.

2. Superficial second-degree sunburn : The symptoms are identical to those of a first-degree burn, with the presence of blisters filled with a clear fluid (phlyctenes) at the level of the epidermis. General manifestations such as headaches, fever, and discomfort can be observed. These symptoms may indicate heatstroke or dehydration. In this case, the healing process will be longer and will take 1 to 2 weeks with a risk of spots and scars that may be slow to fade.

3. Deep second-degree sunburn : This is the most severe case. The blisters have a pale appearance due to the destruction of blood vessels. Unlike the other two types of sunburn, here the pain is minimal as the nerve fibres have been burnt. Healing will take 1 month with a risk of persistent scarring.

In the medium term, just like UVA, repeated sunburn caused by UVB results in a premature ageing of the skin, characterised by the early onset of wrinkles, pigmentation spots, and skin that is loose and dried out. This ageing is explained by an abnormal accumulation of elastic fibres (solar elastosis) and a decrease in collagen fibres in the dermis, due to the genotoxic effects of UVB rays. Indeed, the action of these rays on DNA induces the expression of molecules that disrupt the network of collagen fibres.

In the long run, UVA and UVB rays, being genotoxic, disrupt DNA, causing theemergence of cancerous cells (melanomas).

The risk of sunburn varies according to different factors:

• Age : Children burn 4 times faster than an adult because their skin is thinner. Therefore, infants under 12 months should not be exposed to UV rays.

• Light phototypes : Indeed, the lighter your phototype, the higher the risk of sunburn. Phototypes I to III are the most vulnerable.

• The use of photosensitising molecules : Whether in medications (such as isotretinoin) or in cosmetics (like AHAs and BHAs), the sensitivity of your skin to UV rays will be increased with a heightened risk of sunburn.

• The lack of sun protection : Sun protection is paramount as it provides you with protection against the harmful effects of the sun. Our sun cream for the face allows for broad-spectrum UVA/UVB protection and prevents photoaging.

• Avoid exposing yourself to the sun between 10 am and 4 pm, a period during which UV rays are at their most intense.

• Apply two layers of sunscreen 30 minutes before exposure and renew the application every 2 hours. Choose a broad-spectrum sunscreen that will protect you from both UVA and UVB rays.

• Adopt protective clothing : covering clothes, cap, sunglasses.

If you are already suffering from sunburn, there are soothing actions you can take.

• BERTHELEMY S. Conseil à un patient se plaignant d'un coup de soleil. Actualités Pharmaceutiques (2013).

• YUENG H. & al. Sunburn frequency and risk and protective factors : a cross-sectional survey. Dermatology Online Journal (2021).