Sunlight and Rosacea

Rosacea is a chronic skin condition that primarily affects the face of adults. Rosacea can appear in many different ways on the skin. One common presentation of rosacea is that of a red rash that affects the central face (around the cheeks and closer to the nose). The type of rosacea with redness predominating tends to feature small, fixed, dilated blood vessels (known as telangiectasias).

The other types of rosacea have a predominance of other specific features such as pus-filled bumps (pustules), red bumps, thickened skin (commonly referred to the as phymatous rosacea around the nose), and/or redness in the eyes. These different types and features of rosacea commonly overlap within the same person.

The exact cause of rosacea is unknown but research suggests that there is an overall dysfunction of the immune system. Many patients with rosacea realize quickly that the rash can be triggered or worsened by certain factors. These triggers can include certain foods, heat, alcohol, and sunlight.^[1] Sunlight (and its avoidance) plays an important role in the treatment of rosacea. The use of sun reflecting agents, such as zinc or titanium, is a fundamental part of any treatment regimen for rosacea and it is paramount in treatment success. The reason sun protection is important may be related to research demonstrating that sunlight can worsen rosacea. Ultraviolet radiation (UVR) results in the production of reactive oxygen species (ROS) in the skin.^[2] These highly reactive molecules initiate and propagate inflammation that goes on to trigger the immune system, and ultimately results in an increase in specific rosacea-related molecules in the skin. In addition, UVR increases certain chemical signals in the skin that are known to support blood vessel growth^[3] and therefore may be responsible for the creation of telangiectasias in rosacea. Sunlight also weakens skin support structures (collagen and elastin networks) potentially leading to worsening of rosacea by hindering lymphatic drainage.^[4] 

It is important to note that even the most experienced dermatologist may have difficulty distinguishing the redness of rosacea from sun-induced redness. The difference can be subtle and some have suggested that sun-induced redness is simply a stage of rosacea.^[4] Others point out that the redness of rosacea will typically involve the center of the face and appear rosy pink, while the color from sun-induced redness looks redder and affects the areas of the brows on the lateral face.^[4] Regardless, people with rosacea should consider having a discussion with their healthcare providers about strategies to avoid UVR exposure.