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Bright red or dark blood in the stool: what the colour tells you | CION Cancer Clinics
Bright red blood usually comes from near the exit, most often piles or a small tear, and is usually something harmless. Dark red or maroon blood, or blood mixed through the stool, usually comes from higher in the colon and needs a doctor to look. Black, tarry stool comes from higher still and is an emergency. Colour is a clue to where blood comes from. It is never a diagnosis. 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
Does bright red blood mean something different from dark blood?
Yes. The colour is a rough guide to where the blood came from and how long it spent inside the bowel. Bright red blood has usually travelled only a short way, so it tends to come from the anus, the rectum or the last part of the colon. Dark red or maroon blood has usually come from further up, and has had time to darken on the way down.
Most bright red bleeding is harmless
The commonest causes of bright red blood are piles, which are swollen veins just inside the anus, and a fissure, which is a small tear in the skin at the opening. Both usually show up as streaks on the toilet paper or drops in the pan after straining, often with soreness or itching. Hard stools from too little fibre and water make both more likely.
Dark blood is more often worth checking
Dark red or maroon blood, clots, or blood stirred right through the stool point higher up the colon. Diverticular disease, which means small pouches in the bowel wall, is a common cause. So are inflammation of the bowel and fragile blood vessels in its lining. Polyps and cancer are also on that list, which is why dark blood needs a doctor rather than a home remedy.
Colour tells a doctor where to look first. It does not tell anyone what the cause is.Side by side
How is bright red blood different from dark blood?
Bright red blood
Dark red or maroon blood
Usually from the anus, rectum or lower colon
Usually from higher in the colon, or from brisk bleeding
Streaks on the paper, drops in the pan, a coat on the stool
Mixed through the stool, or passed as dark clots
Commonly piles or a fissure
Commonly diverticular disease, colitis or fragile vessels
Often with straining, pain or itching at the opening
Often with a change in bowel habit, cramps or tiredness
The doctor starts by examining the bottom
The doctor usually arranges a colonoscopy
A growth in the rectum or lower colon can look like this
Polyps and growths higher in the colon can look like this
Other colours you may see
What if the stool is black, or the blood is hidden?
Red and maroon are not the only signs of bleeding. Two of these four matter a great deal, and two are usually food or medicine.
Black, tarry and sticky
Stool that looks like tar, sticks to the pan and smells unusually strong usually means bleeding from the stomach or the first part of the small bowel. Doctors call it melaena. The blood has been partly digested on its long journey, which is what turns it black. Read more on black tarry stools.
This is an emergency. Go today.Dark, but firm and not sticky
Iron tablets and some stomach medicines turn stool dark grey, dark green or black. This stool keeps its normal shape and texture, and it does not look or feel like tar. If you cannot tell which kind you have, treat it as black stool and get checked the same day.
Red that is not blood
Beetroot, red food colouring and some red drinks can tint the stool or the water pink or red the next day. The colour fades once the food has passed through. If you have eaten nothing red, or the colour keeps coming back, assume it is blood until someone has checked.
Blood you cannot see
A slow ooze from the right side of the colon is often mixed in so thoroughly that the stool looks normal. The first sign may be iron-deficiency anaemia, a low haemoglobin, found on a routine blood test. See anaemia as the first sign.
Often noticed as
- Tiredness that sleep does not fix
- Breathlessness on the stairs
- A pale face, lips or nails
Not sure whether this applies to you?
Ask an oncologist
!
Go to an emergency department today if
You pass black, tarry stool, a large amount of blood or repeated dark clots, or you feel faint, dizzy, sweaty or breathless, or your heart races when you stand. Vomiting blood, or something that looks like coffee grounds, is also an emergency. Do not wait for a morning appointment, and do not drive yourself. Any other bleeding that keeps coming back, or comes with a change in bowel habit, weight loss or tiredness, needs a doctor this week.
Commonly believed
Four things people assume about the colour of blood
"Bright red means it is only piles."
Piles are the commonest cause, which is why the belief sticks. A growth in the rectum or lower colon can also bleed bright red, and piles and a growth can be present together. Piles are the explanation once a doctor has examined you and found them. Our page on whether blood is always piles explains how that is decided.
"Dark blood means it must be cancer."
Dark blood is more often from diverticular disease, inflammation or fragile vessels in the bowel wall. It does need a proper look, usually a colonoscopy, because cancer is one of the possible causes. Needing a test is not the same as having the disease.
"No blood in the stool means the bowel is healthy."
Many bowel cancers, especially on the right side, never bleed enough to see. A lasting change in bowel habit, weight loss you cannot explain or a low haemoglobin matter as much as visible blood. If any of those are present, a clean-looking stool settles nothing.
"The bleeding has stopped, so there is nothing to check."
Piles, fissures, polyps and growths all bleed on and off. A quiet week tells you nothing about which one you have. If the bleeding needed checking when it started, it still needs checking after it stops.
Being straight with you
What this page cannot tell you
It cannot tell you where your bleeding is coming from. Colour judged in a toilet bowl, under a bathroom bulb, at a worried moment, is an unreliable guide. Blood mixed with water looks brighter than it is, and a small amount can turn the whole pan red. A doctor needs to examine you, and often to look inside the bowel, before anyone can name the cause.
Colon, rectum or anus?
Bright red bleeding often starts in the rectum or the anus. These are separate from the colon and have their own pages. If a doctor has already said the problem is low down, read about rectal cancer or anal cancer instead. This page covers the colon.
Who this does not apply to
Bleeding in a child has different causes and needs a paediatrician. Piles are common in pregnancy, but bleeding still needs your obstetrician's opinion. If you already have colitis, take blood thinners or are on chemotherapy, follow the bleeding plan your own doctor gave you.
A clear photo can help the doctor understand what you saw. It does not replace an examination.Questions we are asked
Common questions about the colour of blood in stool
Is bright red blood in the stool serious?
Usually not. Most bright red bleeding comes from piles or a small tear at the opening, and it settles once stools are softer. It still needs a doctor's examination if it keeps coming back, or if it comes with a change in bowel habit, weight loss, tiredness or a low haemoglobin.
What does dark red or maroon blood mean?
It usually means the blood came from higher in the colon, or that the bleeding was brisk. Diverticular disease, inflammation and fragile vessels are common causes. Polyps and cancer are less common ones. See a doctor this week, and go to an emergency department today if there is a lot of it.
Can colon cancer cause bright red blood?
Yes. A growth in the lower colon, especially the sigmoid colon just above the rectum, can bleed bright red. Rectal cancer can too, and it has its own hub. This is why bright red blood should be called piles only after an examination, never before one.
Why is blood from the stomach black and not red?
Blood that starts high in the gut is partly digested on its long way down. Acid and digestion turn it black and tarry, with a strong smell. It usually points to an ulcer or bleeding in the stomach or the first part of the small bowel, and it is an emergency.
Do iron tablets make stool look like blood?
They often turn stool dark green or black, which can look alarming. Iron-stained stool keeps its normal texture and is not sticky or tarry. If you cannot tell which you have, or you feel dizzy or weak, treat it as bleeding and get checked the same day.
Should I wait to see if the bleeding comes back?
One small streak after a hard stool, in someone who otherwise feels well, can be watched for a short while. Bleeding that returns, any dark or mixed-in blood, and bleeding with other changes should be seen this week. Black stool, heavy bleeding or feeling faint means the emergency department today.
My stool test was negative. Am I in the clear?
Not if you can see blood or have other symptoms. A negative stool test does not rule out cancer when symptoms are present, and your doctor may still arrange a colonoscopy. A positive stool test does not diagnose cancer either. It is a reason to look inside the bowel.
Where can I get this checked in Hyderabad?
Start with your family doctor, a general surgeon or a gastroenterologist. CION's doctors see people worried about bleeding, and CION arranges a colonoscopy at an accredited partner hospital when one is needed. Call the helpline, describe what you saw, and you will be told honestly which step comes first.
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Dr. C. Raghavendra Reddy
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MBBS (AIIMS), MS (Surgery) (AIIMS), DNB (Surgical Oncology), MRCS (Edinburgh)
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Sources
- NHS — Bleeding from the bottom (rectal bleeding)
- MedlinePlus — GI Bleed
- American Cancer Society — Colorectal Cancer Signs and Symptoms
- NHS — Symptoms of bowel cancer
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
Is blood in stool always piles?Which patterns piles can explain, and which they cannotBlack tarry stools: what they indicateThe one colour that means the emergency department todayBlood mixed into the stoolWhy blood stirred through the stool is checked soonerWhen bowel symptoms are an emergencyA clear list of what cannot wait for a morning appointment
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Not sure what the colour you saw means for you?
Tell us what you have seen and what else has changed, and we will help you decide whether an examination or a colonoscopy is worth arranging. One helpline serves every CION centre.