Definition of Sunburn

sunburnSunburn is Damage to the epidermis and sometimes the dermis, the top and middle layers of the skin, as a consequence of extended, unprotected sun exposure.

The sun emits several wavelengths of ultraviolet light.

Those that reach the earth’s surface are ultraviolet A (UVA) and ultraviolet B (UVB). Each affects the skin in different ways. UVA activates melanocytes, the cells that produce melanin (pigment) and may produce a thermal (heat) response that causes the skin to turn red. Though the skin may feel hot, this is not actually sunburn but rather a thermal (heat) response.

Sunburn is a delayed response to UVB exposure. UVB lightwaves do not activate the melanocytes but instead affect keratinocytes. When the epidermis (skin’s outer layer) contains deeply pigmented keratinocytes, such as in a person who has dark skin or a tan from previous sun exposure, the pigment (melanin) absorbs the UVB and the keratinocytes escape damage. When the skin is light, melanin distribution is also light and there is little absorption of UVB.

Sunburn Pain and Fluid

The keratinocytes bear the brunt of the exposure, and about 8 to 12 hours later show the consequences. The damaged cells release toxins and other substances that draw increased blood flow to the dermis.

The additional blood flow causes the skin to become red (erythema). These toxins irritate the nerve endings in the epidermis and dermis, causing pain. Fluid may accumulate between the cells (edema), causing swelling. With more severe damage, fluid-filled blisters form on the skin.

Discomfort peaks about 48 hours after exposure. At about this same time, the melanocytes have infused keratinocytes migrating from the dermis to the epidermis with melanin, giving them a darker pigment that will offer better protection than their predecessors had.

Treatment for Sunburn

The most effective treatment for sunburn is a combination of moisturizing lotion or gel such as aloe vera to soothe the irritated skin and a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen to relieve inflammation and pain. Most sunburn discomfort resolves in three to five days.

Badly sunburned skin that has blistered is likely to peel at this point and requires gentle cleansing to minimize the risk for bacterial infection until the new skin completely heals.

Researchers now believe one significant sunburn is sufficient to lay the groundwork for skin cancer decades later. Repeated mild to moderate sunburns appear to have similar effect. Sunscreens and protective clothing worn during sun exposure can protect against sunburn.


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