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What causes black or red stools / poo?

Updated on November 5, 2011

I am guessing that either you or someone you know has noticed they have either black or red coloured stools / poo, and as a result you have decided to check out the Internet in order to find out why this is happening, what the cause might be, and if it is something to worry about. Possibly you or your friend may have noticed blood in their stools / poo, which usually causes immediate panic and a fear of all kinds of terrible conditions. You may also have found this article as a result of reading my very popular original article called Have you examined your stools / poo lately?

Most individuals find it very uncomfortable to discuss the colour and nature of their stools or poo with anyone, even close family. They find it embarrassing to talk to their Doctors about these things because it just seems a little bit too gross, especially if you have been a patient of the same Doctor for many years on a less 'intimate' basis. This is why so many people resort to the Internet, looking for quick, easy to find answers to their concerns, hoping they can make lifestyle changes to resolve their odd coloured stools, as opposed to finding out they may potentially have a serious problem.

This particular article will cover the possible reasons for black or red stools / poo, but if you want to look into other colours of stools or poo, and find out the causes of these, there is a list at the bottom of this article along with links to those articles.

The Causes of Black Stools / Poo

As I state in all my articles on the reasons for stools to be unusual colours, there are many reasons why your stools / poo may change colour. The same applies to black or red stools, and this is a list of the many reasons that your bowel movements may begin to appear to be black or red, possibly have blood in them, be tarry or sticky in nature and generally not as you would expect a normal stool to be.

Black stools caused by blood:

Black sticky / tarry, foul smelling stools can be caused by the presence of blood in the stool / poo. This is known as melena or melaena and is diagnosed if more than 200ml of blood is found in the stool when a fecal occult blood test is performed. The fact the blood is dark in colour indicates it is 'old' blood, and therefore originated early in the gastrointestinal tract giving enough time for the bacteria/digestive enzymes in the colon to break down the blood into chemicals . This can indicate the following:

  • A bleeding ulcer in either the esophagus, stomach or the small intestine
  • Vascular Malformation, abnormal blood vessels
  • Some kind of trauma or the presence of a foreign body
  • Widened and enlarged veins called varices in the esophagus and stomach
  • A Mallory-Weiss tear, the esophagus has been torn through severe vomiting
  • Bowel Ischemia, a lack of normal blood flow to the intestines
  • Gastritis, an inflamed lining to the stomach

Black stools in general can be caused by:

  • Eating black liquorice
  • Taking iron supplements
  • Taking Pepto Bismol or Kaopectate. This is caused by the active ingredient they contain called bismuth subsalicylate.The dark coloured stools or poo may last for several days, but should return to a normal colour once you stop taking the bismuth subsalicylate
  • Eating lots of green leafy vegetables such as spinach, broccoli etc
  • Eating blueberries or other dark coloured foods
  • Drinking Guinness or red wine

The Causes of Red Stools / Poo

The medical term for a red stool caused by the presence of blood is hematochezia. The fact that the stool / poo is a brighter red in colour can indicate the source of the blood was lower in the gastrointestinal tract. The presence of red blood in the stool can be caused by the following:

Red stools caused by blood:

  • Anal Fissures. These are small tears or ulcers in the sides of the anus usually caused by straining when constipated, giving birth or ulcerated hemorrhoids
  • Colon Polyps. Small growths on the sides of the colon that are thought to be a sign of future colon Cancer.
  • Crohn's Disease and Ulcerative Colitis are collectively known as Inflammatory Bowel Disease (IBD). Unfortunately these disorders are not curable but aspects of the conditions can be treated surgically
  • Internal Hemorrhoids (piles). These are essentially veins in the rectum and anal area. When these become swollen you may experience itching and discomfort, pain and tender external lumps in the anal area. Frequently you will find blood on the toilet tissue when you wipe and may experience a stinging sensation when straining. Creams are available to ease the problem and you can also help them by reducing your caffeine and alcohol intake, and increasing your dietary fibre and water intake
  • Diverticulosis. This is when pouches called Diverticula form in weakened areas of the colon (large intestine). If these Diverticulum become irritated and infected the condition is called Diverticulitis. The two conditions together are called diverticular disease
  • Colon Cancer (Bowel Cancer) can be indicated by dark red or bright red blood mixed in with your stools / poo.
  • Some kind of trauma or a foreign body
  • A small bowel tumour
  • Vascular Malformation, abnormal blood vessels
  • Intestinal infection e.g. bacterial enterocolitis
  • Irritable Bowel Syndrome (IBS).

Red stools in general (False hematochezia) can be caused by:

  • Ingesting red foods such as beetroot, tomatoes, Kool-Aid, red gelatine, hot cheetos and popsicles
  • Certain chemicals within the body
  • Various metabolic actions can cause the imbalances of certain proteins and other chemicals to be removed as waste products by the body. These are expelled in your stools / poo causing them to take on the color of the metabolized substances

Disclaimer: Please remember this article is intended only as a guideline. If you are concerned about the fact your stools / poo appear to have become black or red in colour, then I would urge you make an appointment with your Doctor quickly so that you can get a professional medical diagnosis without relying on the Internet as a reliable source of information.


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    • mistyhorizon2003 profile image

      Cindy Lawson 3 years ago from Guernsey (Channel Islands)

      It probably is nothing to worry about, but to put your mind at rest I would suggest taking a stool sample to your doctor. I am not a doctor and cannot advise you professionally other than to say what you describe would not cause me to be overly concerned. Good luck.

    • profile image

      Blue becca 3 years ago

      Hi. I have a very odd question and I'm hoping you can share some knowledge. I'm a card carrying hypochondriac (just FYI) so I'm usually examining my stools way to closely but any how my question is my stools are sausage like (normal #3 on the chart) but in the cracks there seems to be a different color either dark brown or maybe even maroon (if you squint) I know I'm crazy... I'm 30 healthy active etc. ive done occult fecal tests in office(negative) because a few of the at home ones may have been the slightest bit positive but this seems to bother be otherwise my stool is what id say normal brown just some darker colors at the cracks.. Sorry for the tmi but thanks for all the help.

    • mistyhorizon2003 profile image

      Cindy Lawson 4 years ago from Guernsey (Channel Islands)

      Thank you cosmicathlete for such a kind and heart-warming comment :)

    • profile image

      cosmicathlete 4 years ago

      Dear, Cindy -

      Thank you for doing the extensive research and sharing your results on this subject. My condolences on your loss and I commend your bravery for using your husband's illness to educate others. With Heartfelt Gratitude.

    • mistyhorizon2003 profile image

      Cindy Lawson 5 years ago from Guernsey (Channel Islands)

      Thanks Writer Fox, I had a bad experience losing my first Husband to bowel Cancer, so I did take time to research this series of hubs thoroughly.

    • Writer Fox profile image

      Writer Fox 5 years ago from the wadi near the little river

      I think you've become an expert in this subject. I know many people have concerns that they are embarrassed or afraid to consult a doctor about. I think your articles will help them to better understand if something is a major or a minor problem.

    • mistyhorizon2003 profile image

      Cindy Lawson 6 years ago from Guernsey (Channel Islands)

      If I am reading what you are saying correctly you meant to say you had specks of blood in your stool (not 'cloud' as you typed?) This could be a sign of piles/hemorrhoids or irritable bowel syndrome (based on the discomfort you described).

      My Mother suffers from Acid Reflux too, and although I am not sure if there is a connection, she does suffer from constipation and minor piles too. Her solution is to eat lots of soaked dried apricots and drink prune juice etc.

    • profile image

      Mary 6 years ago

      I have lower back pain and it hurts to sit flat on my but I have specks of cloud in my stool also and lower stomach discomfort. I also have acid reflux

    • mistyhorizon2003 profile image

      Cindy Lawson 6 years ago from Guernsey (Channel Islands)

      Good Luck LadyG, do feel free to post here with how you get on at the Doctors.

    • profile image

      LadyG 6 years ago

      Thanks for providing this info. Fever, chills, intermittent sharp chest pains and nausea one day. Yesterday and today black stools. Gonna call my doctor in the AM to get it checked out. Your article was most helpful.

    • mistyhorizon2003 profile image

      Cindy Lawson 6 years ago from Guernsey (Channel Islands)

      I really hope you are okay Ronnie and that your decision was correct. I lost my first Husband to Bowel Cancer, and whilst they attempted to give him a colonoscopy, it was too late and the bowel was so brittle by then it was impossible to complete the examination (too painful). When he was officially diagnosed it was about a month later when he had been rushed into the hospital in agony. Surgery revealed the advanced stage of the Cancer, and he was given between six weeks and six months to live. He died within two weeks. He was aged just 48. I hubbed on the experience if you want to read about it:

      It might make you reconsider having that colonoscopy.

      Take Care


    • profile image

      R. J. Lefebvre 6 years ago

      Misty, I experienced some stool color problems and the doctor tried to encourage me to have an colonoscopy; of which I refused because my stool problem was not repetitive and I felt the medical industry was looking for more business, and/or they weren't sure of their patients intellect for recognition. I'm in charge of my body, if I made a mistake I'll continue to live with gusto to the end.


    • mistyhorizon2003 profile image

      Cindy Lawson 6 years ago from Guernsey (Channel Islands)

      Cheers ausis, I am glad you have helped in your 'poo education' lol :)

    • ausis profile image

      ausis 6 years ago from Australia

      Hmmm certainly smacks of or like politics. Yeah I know it's not but hey you need to have a laugh at them when they all start going at each other. Anyway misty great article. I knew a little about poo from my Chinese medicine studies but not this much. ;)

    • profile image

      Hubertsvoice 6 years ago

      I don't blame you.

    • mistyhorizon2003 profile image

      Cindy Lawson 6 years ago from Guernsey (Channel Islands)

      Definitely coincidence Hubert, I avoid politics like the plague :)

    • profile image

      Hubertsvoice 6 years ago

      This was a very useful article. I must ask though, do all of the articles on poop and BS have anything to do with the political campaigns this year or is it merely coincedence?


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