What is the difference between a rosacea and a lupus rash?

Big difference. Rosacea tends to be a reactive process in response to various stimulants that may eventually produce long term skin changes such as rhinophyma that are commonly treated with avoidance and antibiotics whereas lupus is associated with a "butterfly" rash that is a manifestation of an underlying autoimmune disease that are commonly treated with steroids.

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What is the difference between roseca and lupus rash?

see below. A nasal redness, enlargement and roughening, often attributed to alcohol ingestion is quite different from lupus rashes. They typically affect the malar (cheek) region and nasal bridge, with or without scarring (depending on regular lupus or discoid lupus. Read more...