The five facts to know about rosacea.

Rosacea is a stigmatising dermatosis due to the intense redness it causes. It can be difficult to cope with and may lead those who suffer from it to isolate themselves. Moreover, it is often mistakenly believed by their peers to be a contagious disease. It is important to know that rosacea cannot be transmitted horizontally, that is, from an affected person to a non-affected person.

However, studies suggest a link between genetics and the development of rosacea. Indeed, about 30% of people with rosacea have family history of this condition. The genes involved have not yet been identified, but it is assumed that there is a prevalence of certain receptors involved in inflammatory mechanisms in affected individuals. Thus, the only possible transmission of rosacea is vertical, that is, from a parent to their child.

Contrary to popular belief, children can also be affected by rosacea. Indeed, although this disease is predominantly observed in women aged 40 to 50, children are also susceptible. The skin manifestations are then the same as in adults, with redness and sensations of warmth, especially on the cheeks. In some cases, small pimples may also appear.

Several studies have demonstrated that heat can exacerbate the symptoms of rosacea and promote flare-ups. Indeed, a rise in temperature contributes to the dilation of blood vessels and the characteristic inflammations of this form of rosacea. Heat also intensifies the irritations and hot flushes associated with the condition. Indeed, the TRVP1 receptors in the epidermis, involved in nociceptive mechanisms and the pathogenesis of rosacea, activate in response to a thermal stimulus. That's why it is recommended for individuals suffering from rosacea to avoid exposure to excessive heat.

Without treatment , rosacea can worsen over time with flare-ups of spots (papulopustular rosacea). This form of rosacea typically results from the colonisation of the sebaceous glands by the parasite Demodex, which triggers the secretion of TNF-α and interleukin-1 (IL-1), mediators of inflammation. In some cases, a thickening of the skin on the nose is also observed, leading to a rhinophyma (hypertrophic rosacea), a very severe form mainly due to the aesthetic discomfort it causes. Finally, rosacea can also become complicated and affect the eyes, causing them to become dry and red.

It is crucial to consult a dermatologist in the case of rosacea to obtain suitable treatment and prevent the condition from progressing to more severe forms.

Contrary to appearances, rosacea is not purely a physical concern but can also induce anxiety. Some individuals struggle greatly with their rosacea, with their self-confidence being undermined by this condition. All areas of their life can be affected: family, work, relationships. That's why a tailored approach is so crucial, to minimise as much as possible the impact of rosacea on patients' quality of life. Furthermore, psychological support may also be relevant for those who feel the need for it.

• LÉAUTÉ-LABRÈZE C. & CHAMAILLARD M. Rosacea in children. Annals of Dermatology and Venereology (2007).

• STEINHOFF M. & al. Recent advances in understanding and managing rosacea. F1000 Research (2018).

• ALI F. & et al. Rosacea. British Journal of Hospital Medicine.(2021).

• TAN J. & al. Rosacea: new concepts in classification and treatment. American Journal of Clinical Dermatology (2021).