Types of Stool: What Doctors Want You to Know About Your Bowel Movements

Discussing the types of stool may seem disgusting or at least embarrassing, but paying attention to what’s coming out of you can give you great insight into your health. A bowel movement is the last stop your food makes as it goes through your digestive tract. As it turns out, what is left over after your body has absorbed all possible nutrients from your food are the bits that you couldn’t digest, bacteria, salt, and some intestinal substances that assist with processing your meals.

Taking a close look at your stool can tell you quite a bit about the state of your health, especially when coupled with an understanding of what your bowel movement is telling you.

Consistency

Many gastroenterologists refer to the Bristol Stool Chart when talking about the issue of consistency, and encourage their patients to refer to the chart when describing their bowel movements to their physicians. “There are seven consistencies represented by the chart,” explains Jeffrey Nelson, surgical director at the Center for Inflammatory Bowel and Colorectal Diseases at Mercy Hospital in Baltimore, Maryland. The consistency of normal stool should be in a sausage shape, either smooth or with cracks on the surface.

Constipation

When stool falls into one of the first two categories (from separate hard lumps to lumpy, sausage-like stool), that’s considered constipation. Constipation usually goes along with having fewer than three bowel movements per week, according to Lynn O’Connor, chief of Colon and Rectal Surgery at Mercy Medical Center and St. Joseph Hospital in New York. Mechanically speaking, constipation is caused by the intestines absorbing too much water from food. This can be the result of:

• Not enough liquids in the diet
• Certain medications
• Lack of exercise
• Lack of dietary fibre
• Irritable bowel syndrome (IBS)
• Crohn’s disease (an autoimmune disorder that targets the gut)
• Frequently “holding it in”
• Pregnancy
• Laxative overuse

Never ignore constipation because, whatever the cause, it can lead to uncomfortable and unpleasant complications such as hemorrhoids, fissures, and rectal bleeding.

Diarrhea

Stools that fall into one of the last three categories on the Bristol scale—soft blobs with clear-cut edges, mushy, or entirely liquid—are considered diarrhea, and they indicate your food is passing too quickly through the digestive system. Diarrhea can be a sign that you aren’t eating enough fibre, according to Dr. O’Connor. Therefore, upping your fibre intake might help. Often, these types of stool are a sign your body is trying to flush out a problem, such as:

• Food poisoning
• Infections, including Clostridioides difficile, or C. diff, which is almost always accompanied by stool with a distinct and noxious odour
• Parasites, including tapeworm
• Undigestible “foods” including sugar substitutes like xylitol and sorbitol

If your diarrhea is chronic, you should definitely see a doctor to determine the cause. Potential sources of trouble can be celiac disease (an inability to tolerate gluten), Crohn’s disease, or colitis (inflammation from an infection or an autoimmune attack). Diarrhea also happens to be one of the few non-respiratory symptoms of Covid-19.

Shape

If your types of stool occasionally fall into a non-normal category on the Bristol Stool Chart, you don’t have to be alarmed. However, if you have pencil-thin stools, that can be a sign of a physical blockage in the lower GI tract indicating a growth, scarring, or another worrisome condition. If your stool suddenly changes from “normal” to pencil-thin, you’ll want to have that checked out by a doctor, Dr. Thomas advises.

Frequency

According to a 2017 study using data from a nationwide survey, the vast majority of individuals (95 percent) move their bowels three to 21 times per week. And according to our gastroenterological experts, anything in that range counts as normal. “Some of my patients are surprised to hear that a normal frequency for bowel movements is anywhere from three per day to three times per week,” Dr. O’Connor says. But it’s also important to consider what your normal is. If you usually move your bowels five times a week, and suddenly, you’re doing so a lot more frequently, it may be valuable to seek medical advice if the new pattern continues.

Colour

Generally speaking, a normal stool is brown thanks to the presence of a bile pigment called stercobilin—it’s produced when the hemoglobin in red blood cells breaks down, explains Harry Thomas, a gastroenterologist in Austin, Texas. Although bile begins as greenish-yellow, says Dr. Nelson, it turns increasingly brown as it travels through the gut. The longer it takes for waste to make its way through the gut, the browner the stool will appear; the faster it goes, the closer to greenish-yellow it will appear. So although brown is the normal colour, there are many variations.

Black stool

Some medications can also stain stool, Dr. Thomas says. For example, bismuth (the active ingredient in Pepto-Bismol) can colour stool black. So can taking iron supplements and ingesting activated charcoal. Just keep an eye out for a tarry quality to your stools, especially when accompanied by an unusually offensive smell. This can indicate bleeding from the upper portion of the GI tract; the black colour is due to the digestion of hemoglobin from red blood cells.

Pale or clay-coloured stool

If you’re passing either pale or clay-coloured stools, you have a cause for concern, Dr. Nelson says. This can be a sign that the flow of bile is obstructed, he explains, “which could be anything from a gallstone blocking the bile duct to nasty tumours, such as pancreatic cancer and bile duct cancer.” Chronic pancreatitis that has scarred the bile duct also can cause this. Pancreatic cancer is only a concern if the stool colour is combined with worrisome symptoms such as dark urine and a greasy or oily stool. In any event, pale or clay-coloured stools (also called acholic) should be evaluated promptly and aggressively, Dr. Nelson advises.

Green stool

You may remember that a green stool can be a function of how quickly food is travelling through your gut. This could be the result of a metabolic issue such as IBS. It can also be due to something in your diet, notes Dr. Thomas. Foods that can turn your stool green include:

• Green vegetables (leafy greens, peppers, peas, asparagus)
• Green fruits (grapes, honeydew, kiwi, avocado)
• Pistachio nuts
• Hemp seeds
• Green herbs (parsley, basil, cilantro)
• Matcha tea
• Anything containing green food colouring

(Related: Learn about the diet changes to make if you have IBS.)

Yellow stool

Yellow stool can be caused by yellow and orange foods such as turmeric, carrots, yams, and any food containing yellow food colouring, says Dr. O’Connor. However, yellow stool can sometimes be due to metabolic conditions that interfere with digestion and absorption, including celiac disease. Yellow stool can also be caused by liver issues, including cirrhosis and hepatitis, Dr. Thomas says. Accordingly, continuing yellow stool should always be evaluated by a physician.

Red stool

The rule that your food can influence the colour of your stool is especially true with red stuff, according to Dr. Nelson. Take note if you happen to be a fan of:

• Red Jell-O
• Red Kool-Aid
• Red candy such as licorice
• Anything with red food colouring
• Any naturally occurring red produce (such as beets, red peppers, rhubarb, tomatoes, cranberries, paprika)

Because reddish stools can also be a sign of bleeding from the lower gastrointestinal (GI) tract, discuss this with your GP, advises Dr. Thomas.

When to see a doctor

In addition to chronic diarrhea and constipation and certain problematic types of stool mentioned above, the following signs should prompt you to call your physician. Your symptoms may turn out to be nothing, but checking in with your GP can help you rule out serious trouble.

The presence of blood

It can be alarming to see actual fresh, red blood after elimination, but this is most often due to a benign and treatable condition like hemorrhoids or anal fissures. More serious intestinal bleeding leads to tarry black stools, not red blood on the surface of the bowel movement, mentioned previously. Nevertheless, the presence of blood in stool is not normal, points out Dr. Thomas.

It floats

You might notice that your bowel movements tend to sink. Stool that floats higher in the water may be caused by the presence of gas in the GI tract; if you’re eating more fruits and vegetables, it could explain the buoyancy of your stool. However, if your floaters are greasy and foul-smelling, this could be a sign of problems with your pancreas, including chronic pancreatitis and pancreatic cancer. According to Dr. Nelson, when the pancreas isn’t functioning properly, it no longer secretes the necessary enzymes that help break down fat so that it can be absorbed along the GI tract. Instead, it travels through the digestive system, ends up in your stool, and leads to floaters.

It won’t flush

Another sign of pancreatic insufficiency is a stool that sticks to the bowl and is difficult to flush. This can also be a sign of gastrointestinal infections and celiac disease.

There’s mucus

While it can be normal to pass some amount of mucus along with stool, note both Dr. Thomas and Dr. Nelson, large amounts of mucus can signal IBS.

It smells worse

Yes, most types of stool stink, but according to Glenn H. Englander, a gastroenterologist in Palm Beach, Florida, you should be concerned about smells that are particularly strange or foul. Certain illnesses—C. diff is one—will crank up the stink on your stool.

Itchiness during bowel movement

There are many possible reasons for itchy skin down there, but when your anus feels itchy while you’re defecating, it could be a sign of pinworms, according to Dr. Thomas, who notes that they can sometimes actually be seen on the skin or on the surface of feces.

Next, learn about the totally weird things your body does overnight.