When it comes to rosacea diagnosis as such there is no actual proven test. It is generally diagnosed by the specialist by examining the skin of the patient and asks them various questions related to their symptoms. The GP can distinguish rosacea from other skin diseases with the occurrence of increased size of the blood vessels.  If you have developed a rash on the ears or scalp then it probably indicates some other diagnosis.

Most of the symptoms are seen on the face of the patient when affected by rosacea.  If the physician feels that there are certain hidden medical problems then they might suggest you to go for blood test. If the disorder is diagnosed at an early stage, the treatment can be started soon. This will prevent further damage caused by rosacea. If the GP is unable to diagnose the actual problem then he will suggest you to go to a dermatologist. In most of the cases there is eye involvement which needs to be examined. Sometimes they develop in the eye and there are mo lesions of the skin in the initial stage. In order to distinguish it from other diseases, you might require going for a skin biopsy.