Seeing blood in your stool can be worrying. It may appear as bright red blood on toilet paper, red blood in the toilet bowl, blood mixed through the stool, dark red blood, or black, tar-like stool. Sometimes it happens once and settles. Other times it keeps coming back or appears with other symptoms such as pain, diarrhoea, constipation, tiredness or weight loss.
Blood in the stool does not automatically mean bowel cancer. There are many possible causes, including haemorrhoids, anal fissures, constipation, infections, inflammation, diverticular disease, bowel polyps and other bowel conditions. However, rectal bleeding should not be ignored, especially if it is persistent, recurrent, unexplained, or associated with a change in bowel habits.
This article explains what blood in stool may mean, when to speak with your GP, when to seek urgent care, and when further investigation such as a colonoscopy may be recommended.
Article index
- What does blood in stool mean?
- Bright red blood vs dark or black stool
- Common causes of blood in stool
- Can haemorrhoids cause blood in stool?
- Anal fissures and bleeding
- Can blood in stool be a sign of bowel cancer?
- When should you see your GP?
- When to seek urgent medical care
- What to tell your doctor
- What tests may be recommended?
- When colonoscopy may be recommended
- Blood in stool vs a positive bowel screening test
- How Direct Endoscopy can help
- Final thoughts
What does blood in stool mean?
Blood in stool means there is bleeding somewhere in or around the digestive tract. The bleeding may come from the anus, rectum, colon, or sometimes from higher up in the digestive system. The appearance of the blood can sometimes help your doctor understand where it may be coming from, but it is not always possible to know the cause without assessment.
Some people notice a small streak of bright red blood on toilet paper. Others may see blood in the toilet bowl, on the surface of the stool, or mixed through the stool. Some people do not see visible blood at all, but a bowel screening test detects hidden blood in the stool.
Healthdirect advises seeing a doctor if you are worried about rectal bleeding. It also explains that dark red blood may suggest bleeding from the colon, or large intestine. You can read more from Healthdirect.
The most important point is that blood in stool is a symptom, not a diagnosis. It needs to be considered alongside your age, symptoms, medical history, family history, medications and whether the bleeding is new or recurring.
Bright red blood vs dark or black stool
Bright red blood is often associated with bleeding close to the anus or rectum. Common causes include haemorrhoids or anal fissures, especially if the blood appears on toilet paper or on the outside of the stool. However, bright red blood can also occur with other bowel conditions, so it should not automatically be dismissed.
Dark red blood or blood mixed through the stool may suggest bleeding from higher in the colon. Black, tar-like stool can sometimes suggest bleeding from higher up in the digestive tract, such as the stomach or small bowel, although some medicines and supplements can also change stool colour.
It is useful to notice:
- whether the blood is bright red, dark red or black
- whether it is on toilet paper, on the stool, mixed through the stool or in the toilet bowl
- whether bleeding happens once, keeps returning or is getting worse
- whether there is pain when passing stool
- whether bowel habits have changed
- whether you have fatigue, weight loss, abdominal pain or iron deficiency anaemia
If you are unsure what you are seeing, speak with your GP. It is better to ask early than to ignore a symptom that keeps returning.
Common causes of blood in stool
Blood in stool can have many causes. Some are minor and settle with simple treatment. Others need further investigation. Your GP will consider your symptoms and medical history before deciding what is most likely and what tests may be needed.
Possible causes include:
- haemorrhoids
- anal fissures
- constipation or straining
- gastrointestinal infection
- inflammatory bowel disease, such as ulcerative colitis or Crohn’s disease
- diverticular disease
- bowel polyps
- bowel cancer
- bleeding related to some medicines, including blood thinners
- upper digestive tract bleeding, especially if stool is black and tar-like
Because the possible causes vary, the safest approach is not to self-diagnose. For example, haemorrhoids are common, but bowel cancer can also cause bleeding. A doctor can help decide whether examination, blood tests, stool tests, referral or colonoscopy is appropriate.
Can haemorrhoids cause blood in stool?
Yes. Haemorrhoids, also called piles, are swollen blood vessels around the anus or lower rectum. They can cause bright red bleeding, itching, discomfort, a lump near the anus, or pain when passing stool.
Haemorrhoids are common, especially with constipation, straining, pregnancy, prolonged sitting or heavy lifting. In many cases, they are not serious and may improve with changes such as increasing fibre, drinking enough fluids, avoiding straining and using treatments recommended by a pharmacist or GP.
However, you should not assume bleeding is from haemorrhoids unless it has been properly assessed, particularly if bleeding is new, persistent, recurring, mixed through the stool, or occurs with other symptoms. Even if you have had haemorrhoids before, new bleeding still deserves attention if it feels different or does not settle.
Anal fissures and bleeding
An anal fissure is a small tear in the skin around the anus. It can happen after passing a hard stool, straining, diarrhoea or irritation. Fissures often cause sharp pain during or after a bowel movement, along with a small amount of bright red blood.
Many fissures improve with soft stools, avoiding constipation and following advice from your GP or pharmacist. However, ongoing pain, repeated bleeding or a fissure that does not heal should be reviewed by a doctor.
As with haemorrhoids, fissures can explain bleeding in some cases, but they should not be used as a reason to ignore persistent or unusual symptoms.
Can blood in stool be a sign of bowel cancer?
Blood in stool can be a symptom of bowel cancer, although many people with blood in stool do not have cancer. Bowel cancer symptoms can include blood in the stool, changes in bowel habits, abdominal pain, unexplained weight loss, vomiting and unexplained tiredness. Cancer Australia provides more information about bowel cancer symptoms on its bowel cancer symptoms page.
Bowel cancer can also develop without obvious symptoms, especially in the early stages. This is why screening is important for eligible people and why persistent symptoms should be checked.
Blood in stool becomes more concerning when it is persistent, mixed through the stool, associated with a change in bowel habits, linked with unexplained weight loss or fatigue, or occurs with iron deficiency anaemia. Family history of bowel cancer or previous bowel polyps may also affect how urgently your GP investigates the symptom.
The purpose of seeing your GP is not to assume the worst. It is to work out what is causing the bleeding and whether further investigation is needed.
When should you see your GP?
You should see your GP if you notice blood in your stool, especially if it is new, persistent, recurring, unexplained or different from anything you have experienced before.
Book a GP appointment if you have:
- bright red blood that keeps coming back
- dark red blood or blood mixed through the stool
- bleeding with a persistent change in bowel habits
- bleeding with abdominal pain, bloating or cramping
- bleeding with unexplained tiredness or weakness
- bleeding with unexplained weight loss
- known iron deficiency anaemia
- a family history of bowel cancer or bowel polyps
- a positive bowel screening test
- previous bowel polyps or inflammatory bowel disease
Cancer Council Australia advises that people should speak with their GP if they have symptoms such as blood in the stool, changes in bowel habits, stomach pain, unexplained fatigue or weight loss. You can read more from Cancer Council Australia.
When to seek urgent medical care
Some bleeding symptoms need urgent medical attention. Do not wait for a routine appointment if symptoms are severe, sudden or make you feel unwell.
Seek urgent medical care if you have:
- heavy rectal bleeding
- black, tar-like stool
- bleeding with dizziness, fainting or weakness
- severe or worsening abdominal pain
- persistent vomiting
- fever or feeling very unwell
- shortness of breath or chest pain
- bleeding while taking blood-thinning medication
If you are unsure how urgent the situation is, contact your GP, call healthdirect on 1800 022 222, or seek emergency care if symptoms are severe.
What to tell your doctor
It can feel uncomfortable to talk about bowel symptoms, but GPs discuss these issues regularly. Clear information helps your doctor decide what to do next.
Before your appointment, try to note:
- when the bleeding started
- how often it happens
- what the blood looks like
- whether blood is on toilet paper, in the bowl or mixed with stool
- whether passing stool is painful
- whether you have constipation, diarrhoea or a change in bowel pattern
- whether you have abdominal pain, fatigue or weight loss
- whether you take blood thinners, anti-inflammatory medicines or iron tablets
- whether there is a family history of bowel cancer or polyps
You do not need to be embarrassed. The more accurate your description, the easier it is for your GP to assess the likely cause and recommend the right next step.
What tests may be recommended?
Your GP may recommend different tests depending on your symptoms. Not everyone with blood in stool needs the same investigation.
Possible assessments may include:
- physical examination
- rectal examination, if appropriate
- blood tests, including full blood count and iron studies
- stool tests
- review of medications
- referral to a gastroenterologist or colorectal specialist
- colonoscopy
- gastroscopy if upper digestive tract bleeding is suspected
If bleeding is clearly related to a minor cause and settles, your GP may recommend treatment and monitoring. If bleeding is persistent, unexplained or associated with other symptoms, further investigation may be needed.
When colonoscopy may be recommended
A colonoscopy may be recommended when your GP needs the bowel examined directly. This may happen if you have rectal bleeding that is persistent or unexplained, blood mixed through the stool, a change in bowel habits, iron deficiency anaemia, previous polyps, family history of bowel cancer, or a positive bowel screening test.
During colonoscopy, the specialist examines the inside of the large bowel and rectum using a thin flexible tube with a camera. The procedure is usually performed under sedation or anaesthesia. If polyps are found, they can often be removed during the same procedure. Biopsies may also be taken if an area needs closer testing.
A colonoscopy does not mean your doctor thinks you definitely have bowel cancer. In many cases, it finds non-cancerous causes of bleeding. However, it can also detect bowel cancer early and remove polyps before they become more serious.
If colonoscopy is recommended, you will need to follow bowel preparation instructions carefully. Good preparation helps the specialist see the bowel lining clearly.
Blood in stool vs a positive bowel screening test
There is a difference between visible blood in stool and a positive bowel screening test. Visible blood is something you can see. A positive bowel screening test means hidden blood has been detected in a stool sample, even if you cannot see blood yourself.
Australia’s National Bowel Cancer Screening Program is designed for eligible people aged 45 to 74 who do not have symptoms. The test looks for tiny amounts of blood in the stool. A positive result does not mean you definitely have bowel cancer, but it does mean further investigation is usually needed. The Australian Government provides more information about the program on the National Bowel Cancer Screening Program page.
If you can see blood in your stool, do not rely on a routine screening kit as your only next step. Symptoms should be discussed with your GP. Your doctor can decide whether stool testing, blood tests, colonoscopy or another pathway is appropriate.
How Direct Endoscopy can help
If your GP has recommended further investigation because of rectal bleeding, blood in the stool, a positive screening result or related bowel symptoms, our team can help you understand the colonoscopy process and prepare for the procedure.
At Direct Endoscopy, we support patients who need bowel investigation at several Melbourne locations. Colonoscopy allows the specialist to examine the bowel lining and remove polyps where clinically appropriate. If biopsies or polyps are taken, pathology results can help guide the next step in your care.
If you already have a referral, you can contact our team to discuss appointment availability, preparation instructions and expected costs. If you are unsure whether colonoscopy is appropriate, speak with your GP first so they can assess your symptoms, risk factors and medical history.
Final thoughts
Blood in stool can be caused by many conditions, including haemorrhoids, fissures, inflammation, infection, polyps and bowel cancer. It does not automatically mean something serious, but it should not be ignored.
Speak with your GP if bleeding is new, persistent, recurring, unexplained or associated with bowel habit changes, abdominal pain, fatigue, weight loss or iron deficiency anaemia. Seek urgent care if bleeding is heavy, stool is black and tar-like, or you feel dizzy, faint or very unwell.
If your doctor recommends colonoscopy, the procedure can help identify the cause of bleeding and guide the next step. Getting checked early is often the safest and most reassuring approach.