Carcinoid syndrome occurs when a carcinoid tumour, a rare cancerous tumour secretes certain chemicals into the bloodstream, causing an array of symptoms. The carcinoid tumours mostly appear in the lungs or gastrointestinal tract including your stomach, small intestine, colon, appendix, and rectum.
Carcinoid syndrome is caused when a carcinoid tumour releases hormonal chemical substances such as serotonin, bradykinins, tachykinins and prostaglandins into the bloodstream. Just a small percentage of carcinoid tumours secrete these chemicals, and the liver normally counteracts these chemicals before they have a chance to move throughout the body and cause symptoms.
However, when the tumour has advanced to the liver, the chemicals are released that aren’t neutralized before reaching the bloodstream. People with carcinoid syndrome usually have an advanced carcinoid tumour.
Symptoms Of Carcinoid Syndrome 
Skin turns pink, red, or purple colour
Shortness of breath or wheezing
Facial skin lesions
A sudden drop in blood pressure
Complications Of Carcinoid Syndrome 
Carcinoid heart disease – People with carcinoid syndrome can also develop carcinoid heart disease. It is caused due to the thickening of the heart valves, making it difficult for them to function properly resulting in the leakage of the heart valves. The symptoms of carcinoid heart disease are fatigue and shortness of breath.
Carcinoid crisis – It causes a severe episode of flushing, confusion, low blood pressure, and difficulty in breathing.
Bowel obstruction – It occurs when the cancer spreads to the lymph nodes next to the small intestine, causing narrowing of the intestine and leading to bowel obstruction.