Misconceptions about rosacea.

True and false. Numerous studies have revealed a predominance of women among patients suffering from rosacea. This is thought to be due to the production of oestrogen in women, known to be vasodilators and thus causing telangiectasias, one of the main symptoms of rosacea.

However, it is crucial to consider potential biases, such as the location of patient recruitment (hospital, etc.) for instance. Furthermore, a study has shown that men were predominant among patients suffering from papulopustular rosacea, a severe form, identified in a population of employees. These studies, therefore, challenge the traditional data on the sex-ratio in rosacea.

False. Rosacea can also occur in the eyes: this is ocular rosacea. Characterised by tearing, redness, burning sensations and itching, ocular rosacea is an inflammatory disease that causes the dilation of small blood vessels in the white area of the eye (sclera), making them visible, and causing dry eyes. It can also lead to vision problems in some cases.

Furthermore, rosacea can affect the quality of life of patients. They are often affected by social anxiety, associated psychiatric disorders, and low self-esteem. A Chinese study examined the quality of life of 201 patients with rosacea and 196 healthy controls using the Dermatology Life Quality Index and the Hospital Anxiety and Depression Scale. In the rosacea group, the scores for dermatology life quality index, anxiety, and depression were significantly higher.

True. The onset of rosacea appears to be more common in individuals with fair skin and eyes, who are sensitive to the sun and photoaging (skin phototypes I and II). Estimates of the prevalence of rosacea in fair-skinned populations vary from 2 to 22%.

The protective effects of melanin, which is less present in individuals with light skin and eyes, against ultraviolet rays (an exacerbating factor of rosacea) or the genetic differences in susceptibility to rosacea contribute to the lower diagnosis rate in individuals with darker skin. However, the exact causes are still somewhat unclear.

True and false. It is unclear whether alcohol consumption plays a genuine role in the onset or progression of the rosacea. A 2017 study showed that the consumption of white wine or liquor was correlated with an increased risk of developing rosacea. Moreover, the consumption of other alcohols, such as beer and red wine, did not seem to have an impact on the likelihood of developing rosacea. Experts agree that alcohol is not in itself the cause of rosacea, but it can be a risk factor, and this also depends on the type of drink consumed. This topic requires further study.

True. Rosacea is a chronic disease incurable. However, there are treatments available to control the symptoms, the first of which involves avoiding triggers of rosacea flare-ups. There are also oral or topically applied antibiotics, or laser treatments to reduce associated telangiectasias.

False. The rosacea is not a contagious disease, and no possibility of transmission through skin contact or inhalation of airborne bacteria has been demonstrated. This widespread belief is associated with people's perception of those suffering from rosacea, who are stigmatised and feel ostracised.

False. This belief stems from the fact that hot drinks are considered triggers for rosacea flare-ups. However, in reality, caffeine may actually have benefits for rosacea. A study conducted by Wen-Qing LI showed that caffeine consumption from coffee was associated with a decrease in the risk of rosacea in a dose-dependent manner. The absolute risk of rosacea decreased by 132 per 100,000 person-years for the highest compared to the lowest caffeine consumption, and by 131 per 100,000 person-years for the consumption of caffeinated coffee of four servings per day or more compared to less than one serving per month.

One explanation is its effect on vascular contractility. Vasodilation has been documented in the pathogenesis of rosacea and caffeine is known to induce vasoconstriction through its effect on the renin-angiotensin-aldosterone system. An increased intake of caffeine may reduce vasodilation and, consequently, lead to a decrease in rosacea symptoms. Furthermore, it has been demonstrated that caffeine contains antioxidant agents and has immunosuppressive effects, which could result in a reduction of inflammation in rosacea. Finally, hormonal factors have been implicated in the development of rosacea and caffeine can modulate hormone levels, including adrenaline, noradrenaline, and cortisol levels.

False. The onset of rosacea has nothing to do with poor hygiene. No evidence on this subject has been demonstrated. Furthermore, it is important to remember that excessive cleansing and scrubbing of the skin using harsh products can in fact exacerbate the symptoms.

True. Indeed, excessive practice of sport presents a risk of exacerbating symptoms in patients suffering from rosacea. In response to physical exertion, the autonomic nervous system secretes adrenaline. The blood vessels dilate, warm blood rushes to the face and the skin reddens. It has been demonstrated that repeated episodes of vasodilation cause a loss of vascular tone and a permanent dilation of the vessels, which can worsen rosacea.