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Top 4 Causes of Dark Brown Stool

Dark brown stool can be caused by dehydration, constipation, IBS, or simply from eating dark-colored foods or iron-rich foods or supplements.
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Last updated October 6, 2021

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Answer our clinicians' questions to get a constipation treatment prescription for $25 and know if your constipation is serious.

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When it comes to poop colors, there are different shades of normal. Looking at your bowel movements can help you understand what’s normal for you and when there may be a problem.

Stool that appears blackish or reddish in color can be a concern. It can indicate blood in the stool and may be a more serious gastrointestinal tract issue.

But stool that simply seems darker than normal may be the result of dehydration, constipation, or eating dark-colored foods or iron-rich foods or supplements. In some cases, it may be caused by digestive conditions such as irritable bowel syndrome (IBS).

1. Food and medications

Pro Tip

Many foods or medications may naturally cause your stool to change colors, including looking dark brown or black. Common foods known to do this include licorice, blueberries, beets, red-colored gelatin or food made with blood (ie blood sausage). Common medications known to do this include iron supplements and/or medications with bismuth including Pepto-Bismol and Kaopectate. —Dr. Chandra Manuelpillai

Symptoms

  • Dark brown stool

Many foods or medications may naturally cause your stool to change colors, including dark brown or black. Common foods known to do this include licorice, blueberries, beets, anything with food coloring, and food made with blood (i.e., blood sausage).

Iron supplements and medications with bismuth, such as Pepto-Bismol and Kaopectate, can also change stool color.

2. Constipation

Symptoms

Constipation can be due to a host of factors, including poor diet, dehydration, being inactive, hormone fluctuations, and a side effect of medication.

In general, constipation can be avoided by eating a fiber-rich diet, increasing water intake, and exercising regularly.

Medications can also cause constipation. If you recently started a new medication, check with your doctor if you get constipated. They may suggest taking the medication at a certain time of day or with certain foods.

Menstruating women may have constipation prior to their period, due to hormone fluctuations. Pregnant women may also get constipation due to the hormonal changes.

Laxatives may be used to treat constipation. However, even over-the-counter (OTC) laxatives can have side effects. Some may also interfere with your body’s ability to absorb other medications you’re taking.

Overuse or prolonged use of laxatives can cause decreased bowel function, like your bowel’s natural ability to contract. This can lead to dependence on them.

If you need to use a laxative on a regular basis, talk with your doctor. Women who are pregnant and children less than 6 years old should not take a laxative without first discussing it with a doctor.

Some people also may experience what’s known as chronic constipation. If constipation does not go away despite making dietary changes, such as increasing fiber intake, see a doctor.

Constipation questionnaire

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3. Irritable bowel syndrome

Symptoms

  • Abdominal cramps
  • Diarrhea or constipation
  • Bloating and/or abdominal discomfort

Irritable bowel syndromes (IBS) is a chronic disorder of the colon (large intestine) that can flare up at different times. There is no definitive cause of IBS, but it could be caused by abnormal muscle movements in the gut. It may also be affected by your nervous system.

Sometimes flare-ups are due to stress, diet, or other changes. IBS can have different symptoms depending on the person, but most experience abdominal cramps or discomfort.

IBS may affect the color and consistency of your stool. You may feel constipated or you may have trouble reaching the bathroom. IBS symptoms can last a long time. If you notice a change in stool color accompanied by abdominal pain or a change in your bowel habits, see a doctor.

4. Gastrointestinal bleed

Symptoms

If your stool is a darker color than normal, it may indicate internal bleeding. You can have both upper and lower gastrointestinal (GI) bleeds.

Upper GI bleeds tend to be from gastritis (inflammation of the stomach lining) or ulcers but there are other causes as well. These usually start off slow and may have no symptoms other than belly pain when eating.

The slow bleed may eventually cause anemia, which causes fatigue, shortness of breath, and dizziness. Once the blood goes through the digestive system, it turns the stool a darker brown and eventually looks black or tarry.

Lower GI bleeds tend to be bright red, bloody stools because there’s not enough time for the blood to be digested to turn the stool a darker brown, black, or tarry. The most common causes of lower GI bleeds are diverticular disease and hemorrhoids. Sometimes hemorrhoids will cause blood-streaked stool, because the blood gets on the stool as it passes.

It is important to discuss bleeding with your doctor as soon as possible. Slower bleeds are less serious, but you should go directly to an emergency department if you are vomiting or have bright red stool, experience symptoms of anemia, or develop any worrying symptoms like chest pain. This can be life threatening.

Dark brown stool in children

Dark brown stool in children should be monitored.

Constipation in children is often due to not getting enough fiber-rich fruits and vegetables, dehydration, and/or behavioral factors, such as a desire for control or holding stool out of fear of using the toilet or not wanting to stop playing. This can be a problem in young children, especially those who were toilet trained recently.

Children often complain of abdominal pain or pain when trying to pass a stool. The best treatment is prevention. Provide a high-fiber diet and lots of water and other liquids. It can also help to encourage a bathroom routine.

If your child still has trouble with passing a stool or complains about pain while using the toilet, see a doctor. Never start a new medication, even an over-the-counter medication, without first discussing this with your child’s pediatrician. This is particularly true with laxatives. Sometimes constipation is due to an underlying problem that should be addressed first.

Constipation questionnaire

Answer our clinicians' questions to get a constipation treatment prescription for $25 and know if your constipation is serious.

See constipation treatment options

Only available in: CA, NY, TX, FL, IL, NC, PA, OH, MI, and WA

When to call the doctor

Dr. Rx

Don’t feel uncomfortable talking about your stool with your doctor. “Everyone poops.” —Dr. Manuelpillai

Most cases of dark brown stool can be managed with your doctor. It is fine to try increasing fluid intake if you think it is from dehydration. If you think it is from constipation, you can try increasing fiber, fluids, and/or exercise before contacting your physician.

If these approaches don’t work or if you are concerned about other possible causes, such as IBS, GI bleeding, or cancer, discuss it with your doctor.

Should I go to the ER for dark brown stool?

You should go to the ER if your dark brown stool is accompanied by these symptoms:

  • Severe abdominal pain/cramping with or without vomiting or being unable to eat or drink.
  • Brown, black, or bright red vomit or stool, which could indicate internal bleeding.
  • Symptoms of anemia, including dizziness, fatigue, shortness of breath, heart palpitations, and/or chest pain.

Treatment for dark brown stool

Pro Tip

The appearance of stool—color, consistency, shape, etc.—can tell you a lot about your health including diet, dehydration, medical problems (i.e. gastrointestinal bleed, malabsorption, liver failure, infections, malignancy, etc.). It is important to monitor your stool regularly. —Dr. Manuelpillai

At-home care

  • Drink more water.
  • Include more fiber-rich foods in your diet.
  • Increase physical activity/exercise.
  • Monitor other symptoms, such as abdominal pain, or whether stool consistency and color stay the same after changing your diet.

Other treatment options

  • Medications (whether over-the-counter or prescribed) after discussing with your doctor.
  • IV-fluid infusions.
  • Tests to determine the cause of a GI bleed or to diagnose IBS.
Hear what 1 other is saying
Effect of drinking apple cider vinegarPosted September 7, 2020 by L.
I'm 57 years old, male. During the pandemic, my stomach had been obviously bloated. The lockdown made it impossible to do physical activity. So, I tried drinking ACV in the morning, as you may know, this is very popular these days. I take 10ml of ACV and mixed it with a cup of cold water and sugar mixture and drink it before I have my breakfast. The next day, I was fine. On the second morning, my stool color changed to reddish brown and same on the third day. So, I will have to ask my doctor if that's just side effect. I do not feel anything unusual though.
Dr. Manuelpillai is a board-certified Emergency Medicine physician. She received her undergraduate degree in Health Science Studies from Quinnipiac University (2002). She then went on to graduated from Rosalind Franklin University of Medicine and Sciences/The Chicago Medical School (2007) where she served on the Executive Student Council, as well as was the alternate delegate to the AMA/ISMS-MSS G...
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