In few persons there is initially dilation of tiny blood vessels under the facial skin, which turn into adult acne. It is this adult acne which is called acne rosacea. These persons are having the tendency of depicting additionally rose or pinkish facial skin coloration, in contrast to patients suffering from acne, whose facial skin is not very red in its color.
 
The rosacea is found in both the genders of all ages, with high frequency of occurrence in women as compared to men, but in the case of men there is increased severity in comparison to women. In persons with dark complexion the frequency of rosacea occurrence is very less in comparison to persons having fair complexion. The children are very rarely affected with rosacea.
 
The precise cause of rosacea occurrence is an unknown mystery. Although genetic factors do play the role in rosacea occurrence, there can be other causes also besides the genetic cause. The Sun exposure, presence mites in the hair follicles and gastrointestinal diseases can be the possible causative factors of rosacea.