To identify the causes of a facial rash, examine the rash to determine the exact location, shape and arrangement, then take note of the rash duration, explains eMedicineHealth. Sudden allergic reactions to chemicals found in makeup and fragrances also help identify potential causes, explains the American Academy of Dermatology.
After identifying the rash type, those inflicted should consider the potential causes, such as allergies, skin conditions or diseases, notes eMedicineHealth. For example, facial rashes, such as eyelid dermatitis, cause eyelid redness and itching on both upper and lower eyelids, states the AAD. Typically, the cause of eyelid dermatitis is an allergic reaction.
Rash shape also helps to identify the type of facial rash. Rash shapes include flat, raised, annular, clear blisters and scales, according to eMedicineHealth. For example, ringworm produces annular shapes, or circular with a defined center, while psoriasis produces scales and thick red areas on the face, elbows and knees.
The duration of a facial rash helps narrow down potential causes. Allergic reactions to health and beauty products, metals or other objects cause a rash that disappears until future contact with the allergens, states the AAD.
Other factors such as itching, redness and pain provide hints to the causes of a facial rash, explains eMedicineHealth. Hives, scabies and bug bites, for instance, cause skin to itch, while skin conditions such as psoriasis and eczema typically do not cause itching.