'Flushing' is typically referring to redness of the face, or other parts of the body, that is physiologic due to many reasons. This is typically distinguished from blushing which is thought to be a less robust response associated with certain emotions such as embarrassment. There are numerous different things that can cause flushing. For example; inflammation, physical exertion, emotions, caffeine, alcohol, histamines, mastocytosis, and rosacea are just some of the potential causes. As you can see, some of the causes are things that you ingest, some may be normal responses (like emotions), and some may be parts of a medical condition (like mastocytosis, or rosacea). Even taking too high a dose of a vitamin such as niacin can cause facial flushing. Without being able to examine you, or look at your medical history and a list of what medications you take, it is hard to tell you with any certainty exactly what is going on in your particular case. Of course dermatologic conditions can cause redness of the skin, so perhaps the best place to start with trying to figure out why you have facial flushing is with a dermatologist
. I wish you all the best.