Why Is Your Colostomy Bag Fluid Black, and What Does It Mean?

black liquid colostomy bag
Black liquid colostomy bag

It's normal to find some mucus or digestive fluid in your colostomy bag. Depending on things including your nutrition, these fluids' colour and consistency can change. However, it might also be a sign of a serious medical condition.

An abdominal hole known as a stoma allows faeces to bypass a portion of the gastrointestinal (GI) or urinary system.

For stool to skip your lower colon and collect in a colostomy bag, a surgeon must attach a portion of your large intestine to a hole in your belly.

The presence of black fluid in your colostomy bag may indicate GI haemorrhage. Other, less severe causes include:
  • colourants in your food
  • digestive juices and the charcoal in your bag's filter combining
  • adverse effects of medicine
This article discusses a few potential causes of black fluid buildup in colostomy bags.

What causes black stoma output?

While many black stoma discharge reasons are not alarming, some are dangerous. A medical expert can assist you in identifying the underlying problem.

Bleeding in the digestive system

Your faeces may turn tarry black as a result of GI haemorrhage. Stomach ulcers are the primary source of GI bleeding. Blood in the GI system can combine with mucus or digestive juices and turn them dark.

Due to the activities of digestive enzymes and bacteria on the haemoglobin in your blood cells, GI bleeding frequently produces a strong, unpleasant odour.


GI bleeding is an emergency that needs to be treated right away. Get immediate emergency medical help if you have:
  • Your colostomy bag's black fluid or faeces is what's producing the bad odour.
  • colostomy bag fluid or stool that is bright red when you haven't eaten anything with vivid red pigment.
  • paleness
  • shortness of breath
  • abdominal cramping
  • dizziness
  • faintness
  • coffee-grounds-like vomit


The pigments in some foods can alter the colour of your stool or digestive juices. Your stool may seem black if it contains pigments that are black, purple, or dark blue.

A class of pigments called anthocyanins gives fruits and vegetables their red, purple, or blue hues. These colours are found in:

  • grapes
  • berries
  • currants
  • some tropical fruits
If you eat these items more frequently than normal, your faeces colour can vary. Your stool and digestive fluid's colour may also alter if you consume highly processed meals with additional colours, such as black liquorice.


Stools and digestive fluid may appear black when taken with certain drugs including those for iron or bismuth. This often doesn't raise any red flags.

People frequently take bismuth-containing medicines to address GI issues. For instance, Pepto-Bismol's active constituent is bismuth subsalicylate.

Filter dust particles

Charcoal is commonly used in colostomy bags to absorb odours brought on by gas expelled from the bag. If the filter gets moist, some users could detect black fluid emerging from the vent holes. Typically, this is not a cause for alarm.

A stoma infection or necrosis

Necrosis is the absence of blood flow-induced death of tissue surrounding your stoma. According to several reports from a 2022 assessment of the literature, up to 16% of patients who undergo stomas may experience necrosis.

Theoretically, dead and black tissue fragments could make their way into your colostomy bag and colour your stool or fluid.

Theoretically, some infections could also cause this to occur.

Why is my stoma output watery?

Liquid from your stool is absorbed by your large intestines. Your stools may be more watery after surgery if you have a colostomy bag because it bypasses a portion of your large intestine.


Stoma obstruction symptoms include passing watery stools along with a decrease in stool volume or no stools at all. Stoma blockages are medical emergencies that need to be attended to right away. If you also suffer any of the following symptoms, go to the nearest emergency room:
  • abdominal cramps
  • nausea and vomiting
  • swelling or bloating

What causes the yellow liquid in my colostomy bag?

You should consider your diet if you have yellow liquid in your colostomy bag. Your intestinal lining's mucous could potentially be the cause. It's normal for your bowels to generate some mucus, but if you experience any additional unsettling symptoms, you should see a doctor.

What colour should colostomy drainage be?

Depending on what you eat, the fluid in your colostomy bag may be of varied colours. For instance, eating beets might result in vivid redness that may resemble blood.

Your stool will often be brown. Since they frequently mix, the fluid in your colostomy bag is frequently the same colour as your stool.

What are the symptoms of an infected stoma?

Stoma infection signs and symptoms include:
  • redness, which may be difficult to notice on darker skin tones
  • pus
  • swelling
  • other colour changes

When to call your doctor

If you observe any unsettling changes in your stool or fluids accumulating in your colostomy bag, you must immediately call your doctor.

If you experience indications of a blockage, such as fluid accumulating in your colostomy bag in the absence of faeces, you must seek immediate medical assistance.

Taking care of the fundamental issue

If you have black fluid in your colostomy bag, you may receive the following treatments:

GI bleeding• medications
• endoscopic surgery
• injections
Medications• no treatment is usually needed
Diet• no treatment is usually needed
Infection• antibiotics or antifungals


A black fluid in your colostomy bag may indicate that your GI tract is bleeding. GI bleeding is a medical emergency that needs to be treated right away.

Additionally, black fluid may have a minor cause, such as:
  • particles from the filter's charcoal
  • colour from your diet
  • adverse effects of medicine

Even while these causes are typically not dangerous, it is always vital to speak with your healthcare team if you see any unusual changes.


Can a stoma bag burst?

Due to an abundance of gas, your bag bursts.

Can colostomy be cured?

An end colostomy can also be reversed

Is a stoma life-threatening?

Life-threatening complications are rare

Is colostomy a high-risk surgery?

A colostomy is a major surgery.

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