Carcinoid syndrome can be difficult to determine because it mimics the symptoms of other conditions. Flushing is the most common symptom of carcinoid syndrome, and often the symptom that presents first. However, there are many other conditions that can cause flushing. It might also be caused by side effects of medications you may be taking.
https://www.carcinoidsyndrome.org/understanding-carcinoid-syndrome/carcinoid-syndrome-101/

