Symptoms of Carcinoid Syndrome
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The Symptoms of Carcinoid Syndrome

If you have been diagnosed with carcinoid syndrome, you probably have already experienced at least some of the symptoms. Because many of the early symptoms of carcinoid syndrome are difficult to diagnose, many people live with the symptoms for years before learning what the problem is. Identifying the symptoms of carcinoid syndrome early is a benefit in fighting the condition. This section may help you better understand the symptoms of carcinoid syndrome. Not every person with carcinoid syndrome will have all of these symptoms.

Carcinoid Syndrome Symptoms
Carcinoid Syndrome Symptoms
A graph shows the frequency of signs and symptoms of carcinoid syndrome occurring in a sample of 138 cases. Click on a symptom from the list below to learn more about it.

It is important to always keep your health care team informed if you experience any of these symptoms, so you can better manage your disease.


Over 90% of people with carcinoid syndrome experience flushing. Flushing resembles an intense blush, a deep red or purple hue that appears suddenly on the face or neck—although the flush may appear on the upper back or legs as well. The flush can be triggered by emotions, by eating, or by drinking alcohol or hot liquids. When it occurs, you may feel warm or unpleasant sensations in the affected areas, and be aware of having a rapid heartbeat. The flush is caused by dilation of the blood vessels in the affected area of skin. It can last from a few minutes to hours, and in some cases may even be constant. The stage of carcinoid syndrome you are in can determine how long flushing lasts. In more severe cases, facial skin sometimes thickens and discolors. Flushing in carcinoid syndrome is more likely to be "dry" flushing (flushing that is not accompanied by sweating) rather than "wet" flushing (flushing that is accompanied by sweating).

Flushing on the back
Flushing on the back. Photograph courtesy of L. Anthony, MD.

Facial flushing
Facial flushing. Note the thickening of the skin in this severe case. Photograph courtesy of A. Benson, MD.

Flushing on the legs
Flushing on the legs.

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About 78% of people with carcinoid syndrome experience diarrhea, which can occur with flushing or by itself. Stools are watery and the diarrhea can be mild or severe. Episodes can occur several times a day and can interfere with daily life. Patients with severe cases of diarrhea often have trouble leaving their homes for work, social functions, or activities that require being away from home and on the move for a long time. In addition, diarrhea can drain your body of water, causing dehydration and electrolyte loss. Without enough water and electrolytes, proper digestion cannot occur, and your body cannot get the nutrients it needs. This can worsen the weight loss, weakness, and fatigue that may have already have been caused by the loss of fluids and electrolytes. The diarrhea that results from carcinoid syndrome may also occur at night (nocturnal diarrhea).

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Heart valvular lesions

One of the more serious symptoms of carcinoid syndrome is heart valvular lesions, a condition in which excess serotonin causes injury to the valves of the heart. This leads to a unique set of problems with the way your heart functions, called carcinoid heart disease. Cardiac disease develops in 11% to 66% of carcinoid patients.

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Many people with carcinoid syndrome experience abdominal cramping, a painful condition in which normal bowel movements are prevented. These cramping episodes may occasionally develop into intestinal obstruction, a serious condition that requires medical attention.

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People with carcinoid syndrome sometimes develop telangiectasia, reddish spots or veins that appear most often on the face, chest or arms. These are caused by prolonged flushing.

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Peripheral edema

Peripheral edema, a swelling of the ankles, legs, hands and arms, or neck and face, may also occur in people with carcinoid syndrome. This symptom may be a sign of heart problems, and you should see your doctor if you notice it.

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Exposure of lung tissues to abnormally high levels of certain substances can cause the blood vessels to constrict, and narrow the airway passages, making it difficult to breathe. This wheezing can be mistaken for asthma.

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Cyanosis refers to characteristic bluish skin spots that can develop in people with carcinoid syndrome. The spots may appear after flushing, and are produced by a lack of oxygenated blood circulation in the affected areas.

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Although the causes are not known, people with carcinoid syndrome are more likely than the general population to develop arthritis.

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Pellagra is a disease of nutritional deficiency that causes symptoms such as skin rash because of the lack of niacin.

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Learn how carcinoid syndrome is diagnosed