Scars are patches of fibrous tissue replacing normal skin after injury and are sensitive to environmental factors. The idea that sunlight can help “heal” a scar by tanning it is a common misconception. Exposing a developing scar to ultraviolet (UV) radiation is detrimental to its long-term appearance. Sun exposure disrupts the delicate process of skin repair, leading to permanent discoloration and textural changes. Proper sun protection is necessary to minimize the visibility of a scar as it matures.
Why Scar Tissue is Vulnerable to UV Rays
Healing scar tissue lacks the natural defenses present in healthy skin, making it highly susceptible to damage from ultraviolet light. New scar tissue is often thinner than the surrounding dermis and epidermis, allowing UV-A and UV-B rays to penetrate more deeply. This reduced structural integrity offers less physical protection against solar radiation.
A major protective difference is the immature distribution of melanocytes, the cells that produce the protective pigment melanin. These cells are often less active or disrupted, leading to poor natural UV absorption in the scarred area. This lack of robust melanocyte activity means the scar cannot “tan” for protection and is at a higher risk of sunburn compared to adjacent skin.
UV exposure also triggers an inflammatory response in the healing tissue, which can destabilize internal repair mechanisms. UV radiation accelerates the breakdown of collagen, a fibrous protein that provides structure to the skin. This disruption impedes the orderly remodeling of collagen fibers, which determines the scar’s ultimate appearance.
How Sun Exposure Affects Scar Appearance Over Time
The cosmetic consequences of exposing a scar to sunlight involve changes in color and texture that make the mark more noticeable. The most common outcome is post-inflammatory hyperpigmentation (PIH), where the scar darkens (turning brown or purple) in response to UV stimulation. Inflammatory mediators, combined with UV exposure, cause the melanocytes in the area to overproduce pigment.
This darkening can become permanent or require extensive treatment to fade, especially if exposure occurs during the first year of healing. Conversely, sun exposure can sometimes cause hypopigmentation, making the scar appear lighter than the surrounding skin due to melanocyte destruction or inactivity. However, hyperpigmentation is more frequent.
Regarding texture, UV damage leads to a less uniform and more pronounced scar. The sun’s ability to break down forming collagen can stimulate a compensatory overproduction of new collagen, potentially contributing to a raised, thickened appearance known as a hypertrophic scar. Sun exposure prolongs the time it takes for the scar to soften, flatten, and mature into its final, less conspicuous state.
Protecting Scars from Sunlight
Protecting a developing scar from the sun is necessary to achieve the best possible long-term aesthetic outcome. The most effective method is complete physical blockage of the UV rays. This includes covering the scar with clothing, a bandage, or a silicone sheet, especially during peak sun hours (10 a.m. and 4 p.m.).
When complete coverage is not possible, a high-quality, broad-spectrum sunscreen should be applied diligently. The sunscreen must have a Sun Protection Factor (SPF) of 30 or higher to block both UVA and UVB rays. Mineral sunscreens containing zinc oxide or titanium dioxide are recommended because they physically block the rays and are less likely to irritate sensitive, healing skin.
Sunscreen must only be applied once the wound is fully closed. It should be reapplied every two hours, or immediately after swimming or heavy sweating. Consistent sun protection is most important during the scar’s initial maturation phase, which typically lasts for the first six to twelve months after the injury. Maintaining this protection minimizes the scar’s final color and texture.