Carcinoid Syndrome and Crisis

Carcinoid syndrome is a set of symptoms that may occur in patients who have carcinoid tumours (neuroendocrine tumours, or NET, often in the gastrointestinal [GI] tract or lungs). Not all people with carcinoid tumours have carcinoid syndrome. Carcinoid syndrome occurs when carcinoid tumours overproduce substances such as serotonin that normally circulate throughout your body. When excess serotonin reaches tissues in the GI tract, the lungs, or the skin, it causes some of the symptoms of carcinoid syndrome. The two main symptoms of carcinoid syndrome are flushing (temporary reddening of the skin), and diarrhea1.


Carcinoid crisis causes a severe episode of flushing, low blood pressure, confusion and breathing difficulty. It can occur in people with carcinoid tumours when they are exposed to certain triggers, including anaesthetic used during surgery. Carcinoid crisis can be fatal. Your doctor may give you medications before surgery to reduce the risk of carcinoid crisis2.

2 Mayo Clinic