Rosacea: An Introduction

What Causes Rosacea?

The cause of rosacea is poorly understood, although numerous theories have been offered.

Hypotheses have included:

  • gastrointestinal
  • psychological
  • infectious
  • climatic and
  • immunological causes

although scientific evidence has not substantiated any of these as primary.

Controlled studies have not demonstrated consistent preponderance of gastrointestinal symptoms in rosacea patients.

Similarly, neither a distinct psychological abnormality nor one pharmacological mechanism has been isolated in rosacea patients.

Perhaps the most commonly touted of the etiologic theories is based on the presence of Demodex folliculorum in patients with rosacea.

Demodex folliculorum has been considered a causative agent of rosacea in the past.

The organism feeds on sebum, and in some cases treatment of demodex infestation has noted improvement in the rosacea.

However, in a review of 79 biopsies, Marks noted demodex folliculorum in only 19% of the specimens.

A bacterial cause for the disease has been hypothesized, but no consistent findings of one bacteria have been demonstrated.

Climate, specifically exposure to extremes of sun (also see rosacea sunscreens) and cold, may have an effect on the course of the disease, but the role of climate in what appears to be a connective tissue disorder is not clear.

Finally, an auto immune process has been suggested, and tissue fixed immunoglobulins have been reported in patients with chronic inflammation of rosacea, but no other evidence has been found.

Recent experimental evidence has suggested this disease may represent a type of hypersensitivity reaction such as photosensitivity.

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