Medical Oncologist
CION Cancer Clinics
Nausea, vomiting and bowel obstruction: what the symptoms mean | CION Cancer Clinics
Most nausea and vomiting comes from a stomach bug, food poisoning or acidity, not a blocked bowel. A blockage looks different: cramping pain in waves, a swollen tummy, no stool or wind passing, and vomiting that keeps coming. That combination needs an emergency department today. This page explains the common causes, where colon cancer fits and what the hospital will do next. At CION Cancer Clinics, our specialists help you judge which bowel symptoms need tests and plan screening that fits your risk.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed October 2026, next review due October 2027
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The short answer
Do nausea and vomiting mean the bowel is blocked?
Usually not. Most vomiting comes from a stomach infection, food poisoning, acidity, a migraine or a new medicine, and it settles within a day or two. What points to a blocked bowel is vomiting together with cramping tummy pain, a swollen belly and no stool or wind coming out.
What a blockage actually is
A bowel obstruction means food, fluid and gas cannot move along the gut. It can happen in the small bowel, the long coiled tube after the stomach, or in the colon, the last part of the gut. Blockages in the small bowel bring vomiting early. Blockages in the colon build more slowly, so swelling and constipation usually come first and vomiting comes later.
Where colon cancer fits
A tumour in the colon can slowly narrow it until stool struggles to get past. Some people have weeks of warning, such as new constipation, cramps after meals or thinner stools. Others first learn of the cancer when the bowel blocks completely and they arrive at hospital. Either way, the blockage is treated first and the cause is worked out after.
Vomiting on its own is rarely a bowel blockage. Vomiting with a swollen tummy and no wind passing is different.Most likely first
What can block the bowel, apart from cancer?
Several things can slow or block the gut. Most of them are not cancer, and some are not true blockages at all.
Scar tissue and hernias
Bands of scar tissue, called adhesions, can form after any operation on the tummy, including a caesarean or an appendix removal, and kink the small bowel. A hernia can trap a loop of bowel in a weak spot in the tummy wall or groin. These are among the commonest causes of a blocked small bowel.
A bowel that has stopped moving
After surgery, during a severe infection or with some medicines, the bowel can stop squeezing even though nothing is blocking it. It looks like a blockage and is treated with fluids and rest for the gut.
Also behaves like a blockage
- Hard stool packed in the lower bowel
- Constipation from strong painkillers
- Long spells in bed after illness
Twisting and narrowing
The colon can twist on itself, called a volvulus, more often in older adults. Repeated inflammation of small pouches in the colon wall, known as diverticular disease, can leave a scarred, narrow section. Crohn's disease can narrow the bowel in a similar way.
A tumour in the colon
Cancer is one cause of a blocked colon in older adults. It is more likely when there were earlier signs, such as low iron, weight loss, blood in the stool or a change in bowel habit lasting several weeks.
None of these can be told apart reliably at home. That is a job for a scan.Not sure whether this applies to you?
Ask an oncologist
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Go to an emergency department today if
you cannot pass stool or wind and your tummy is swelling, the vomiting will not stop, the vomit is green, dark brown or smells like stool, the pain is severe and constant, or you have a fever with a hard, tender tummy. Do not take a strong laxative or an enema at home to force things through, and avoid eating until you have been seen. CION centres are not emergency departments, so go to the nearest hospital.
Side by side
Is it a stomach bug or a blocked bowel?
More like a stomach bug
More like a blocked bowel
Loose stools, often with the vomiting
No stool and no wind passing at all
Tummy soft, with mild cramps
Tummy swollen, tight and sounding hollow
Others who ate the same food are unwell too
Past tummy surgery or bowel symptoms beforehand
Vomit looks like food or is clear
Vomit turns green, dark brown or smells of stool
Slowly getting better
Steadily getting worse
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What the hospital will do
What happens when you arrive with a suspected blockage?
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Assessment and a drip
The emergency team examines your tummy, takes blood tests and starts fluids through a drip, because vomiting dries the body out quickly. Pain relief and anti-sickness medicine are given.
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Resting the gut
A thin tube may be passed through the nose into the stomach to drain it. It is uncomfortable, but it eases the vomiting and the swelling. You will not eat or drink for a while.
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A CT scan of the tummy
The scan shows whether the bowel is truly blocked, where the blockage is and often what is causing it. It also shows whether the bowel wall is under strain, which decides how urgent the next step is.
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Relieving the blockage
Many small-bowel blockages from scar tissue settle with rest alone. A colon blocked by a tumour usually needs either a stent, a mesh tube placed through a scope to hold it open, or an operation. The pages on stenting before surgery and emergency surgery for a blocked colon explain each.
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Finding the cause and planning ahead
If a tumour is suspected, a biopsy and further scans follow once you are stable. The tumour board reviews them, and any planned operation is carried out at an accredited partner hospital. The page on being diagnosed in an emergency covers what comes next.
Being straight with you
What this page cannot tell you
It cannot tell you whether your symptoms are a blockage, or what is causing one. That needs an examination, blood tests and usually a CT scan, and none of those can be done over the phone. If you are unsure, it is safer to be seen and sent home than to wait at home.
Who this page does not apply to
It is written for adults with new symptoms. If you already have advanced colon cancer and are getting cramps or vomiting, your situation is different, and the page on managing obstruction in advanced disease is written for you. It does not cover babies or children, vomiting in pregnancy, or a blockage soon after an operation, which your surgical team should handle.
Where CION fits
CION does not run an emergency department, and a sudden blockage must be handled at the nearest hospital. Once you are stable, CION's medical and surgical oncologists can review the scans and biopsy, explain them in plain words and help plan what comes next with you and your family.
If a family member is in hospital with a blocked bowel and the word tumour has come up, call the helpline. Someone will explain the next steps.Questions we are asked
Common questions about vomiting and bowel obstruction
Can colon cancer cause vomiting?
Yes, but usually only once a tumour has narrowed the colon enough to block it, and usually after other signs such as constipation, bloating or cramps. Vomiting without those signs is far more often a stomach infection, acidity or a side effect of a medicine.
Can you still pass stool if the bowel is partly blocked?
Yes. With a partial blockage, some stool and wind still get through, and liquid stool can leak past a narrowing and look like diarrhoea. So passing something does not rule a blockage out. Cramps, swelling and vomiting together still need a doctor.
How quickly does a blocked bowel become dangerous?
It can become serious quickly, sometimes within the same day. A blocked bowel can stretch, lose its blood supply or tear, which causes infection inside the tummy. That is why the advice is to go to hospital today rather than wait to see whether it passes.
Should I take a laxative if I think the bowel is blocked?
No. If you cannot pass wind or stool and your tummy is swelling, a strong laxative or an enema can increase the pain and does not treat the cause. Ordinary constipation without those signs is different, and a pharmacist or doctor can advise on it.
Does a blocked bowel always need surgery?
No. Many blockages caused by scar tissue settle with a drip, a nose tube and rest for the gut. A colon blocked by a tumour more often needs a stent or an operation, and the hospital team decides which is safer once they have seen the scan.
Will an emergency operation mean a stoma?
Sometimes. In an emergency the bowel can be swollen and unprepared, so the surgeon may bring one end out onto the tummy for a while to let things heal. This opening is called a stoma. Many are reversed later, and your surgeon will say which is likely.
My elderly father has not passed stool for days. Is that a blockage?
Not necessarily. Hard stool packed in the lower bowel is common in older or bed-bound people and in those on strong painkillers. It can still cause swelling and vomiting, so if he is in pain, not passing wind or vomiting, take him to hospital today.
Does a blockage mean the cancer has spread?
Not by itself. A blockage shows that a tumour has narrowed the colon. It does not show how far the cancer has gone. Staging scans and the biopsy answer that once the emergency is over, and the tumour board uses them to plan treatment.
Your Specialists
Meet CION's colon cancer specialists. Bring your colonoscopy, scan or biopsy report.
Our surgical and medical oncologists plan colon cancer care together: which operation, whether chemotherapy is needed, and the follow-up that comes after.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
Medical Oncologist
Medical Oncologist
Surgical Oncologist
Dr. Muralidhar Muddusetty
MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
Surgical Oncologist
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Sources
- NHS — Diarrhoea and vomiting
- NHS — Symptoms of bowel cancer
- Cancer Research UK — Symptoms of bowel cancer
- American Cancer Society — Colon Cancer Surgery
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
When bowel symptoms are an emergencyThe full list of signs that mean going to hospital todayStenting a blocked colon before surgeryHow a stent can buy time for a planned operationEmergency surgery for a blocked colonWhat the operation involves if a stent is not possibleBeing diagnosed in an emergency admissionWhat happens after the blockage is relieved
Talk to us
Has a doctor said the bowel is blocked by a growth?
If a scan or a surgeon has mentioned a tumour, we can go through the reports and explain the next steps in plain words. Once the emergency is over, CION's oncologists can help plan what comes next. One helpline serves every CION centre.