My skin on arms face neck and legs are very red and flushed.. and my face feels very hot from within. what could be causing this?

Acute or chronic: If these symptoms just happened they may be a reaction to something you ate or a medication you took. Niacin can make people flush. If you are having other systemic symptoms such as difficulty breathing, you should seek medical attention immediately. If this is more of a chronic problem, it should be worked up by a dermatologist.