ROSACEA
Rosacea is a common but often misunderstood condition that is estimated to affect over 45 million people worldwide. It affects white-skinned people of mostly north-western European descent, and has been nicknamed the 'curse of the Celts' by some in Ireland and Scotland. It begins as erythema (flushing and redness) on the central face and across the cheeks, nose, or forehead but can also less commonly affect the neck and chest. As rosacea progresses, other symptoms can develop such as semi-permanent erythema, telangiectasia (dilation of superficial blood vessels on the face), red domed papules (small bumps) and pustules, red gritty eyes, burning and stinging sensations, and in some advanced cases, a red lobulated nose (rhinophyma). The disorder can be confused and co-exist with acne vulgaris and/or seborrheic dermatitis. Rosacea affects both sexes, but is almost three times more common in women, and has a peak age of onset between 30 and 60. The presence of rash on the scalp or ears suggests a different or co-existing diagnosis, as rosacea is primarily a facial diagnosis.

Causes
Rosacea has a hereditary component and those that are fair-skinned of European or Celtic ancestry have a higher genetic predisposition to developing it. Women are more commonly affected but when men develop rosacea it tends to be more severe. People of all ages can get rosacea but there is a higher instance in the 30-50 age group. The first signs of rosacea are said to be persisting redness due to exercise, changes in temperature, and cleansing.Triggers that cause episodes of flushing and blushing play a part in the development of rosacea. Exposure to temperature extremes can cause the face to become flushed as well as strenuous exercise, heat from sunlight, severe sunburn, stress, anxiety, cold wind, moving to a warm or hot environment from a cold one such as heated shops and offices during the winter. There are also some foods and drinks that can trigger flushing, these include alcohol, foods and beverages containing caffeine (especially, hot tea and coffee), foods high in histamines and spicy food.(1)





source (1) wikipedia