Symptoms of small bowel neuroendocrine tumours

Not everyone with a small bowel NET has symptoms. They can sometimes grow slowly without many signs and symptoms.

When you do have symptoms, they can be caused by the tumour itself or by hormones made by the tumour. Symptoms are often similar to irritable bowel syndrome such as tummy (abdominal) pain and diarrhoea.

These symptoms could be due to a small bowel NET but can also be caused by other medical conditions. It’s important to get them checked out by your doctor.

Symptoms caused by the tumour itself

Symptoms might include:

Tummy (abdominal) pain

This is usually crampy and comes on quickly and often.

Weight loss

You might lose weight even if you haven't changed your diet.

Changes to your poo

You might notice some changes to your bowel movements (poo). You might have tarry, black poo. Doctors call this melena.

Your poo might be looser than normal (diarrhoea).

Feeling tired (fatigue)

You might feel very tired a lot of the time.

High temperature (fever)

You might have a high temperature or feel feverish.

Feeling or being sick

You might feel sick (nausea). You might be sick (vomit) with or without feeling sick before.

Bleeding in the digestive system

Rarely small bowel NETs can cause bleeding. Bleeding into the digestive system (stomach, bowel or back passage), can cause:

  • black bowel motions
  • vomiting blood
  • a swollen tummy (abdomen)
  • difficulty swallowing

Symptoms caused by hormones

Some small bowel NETs make hormones that go into the bloodstream. Doctors call these functioning tumours. These hormones can cause symptoms that don’t seem related to the tumour. Doctors call this collection of symptoms carcinoid syndrome. It is more likely to happen if the small bowel NET has spread to other parts of the body, especially the liver. 

The symptoms might include:

Flushing of the skin

The skin of your face, neck and chest may look red (flushed).


Diarrhoea means having more than 3 watery poos (stools) in a 24 hour period. You might also have diarrhoea at night and problems controlling your bowels (incontinence).


Wheezing is a whistling sound when you breathe.

Fast heartbeat

You may feel that your heart is beating very quickly. This can make you feel dizzy, breathless and tired.

When to see your doctor

You should see your doctor if you have any of these symptoms.

What happens next?

We have information on seeing your GP and the tests you might have.

Last reviewed: 
09 Jun 2021
Next review due: 
09 Jun 2024
  • Management of Small Bowel Neuroendocrine Tumors - Clinical Review 
    Aaron T. Scott and James R. Howe
    American Society of Clinical Oncology, 2018. Volume 14, Issue 8

  • Gastroenteropancreatic neuroendocrine neoplasms: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    M. Pavel and others
    Annals of Oncology 2020, Vol 31, Issue 5 

  • Suspected cancer: recognition and referral 
    National Institute for Health and Care Excellence (NICE), June 2015

  • ENETS consensus guidelines update for neuroendocrine neoplasms of the jejunum and ileum
    B Niederle and others
    Neuroenocrinology, 2016
    Volume 103

  • Neuroendocrine tumours of the small intestine
    J Strosberg
    Best Practice & Research Clinical Gastroenterology, 2012
    Volume 26

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