Bowel habits vary from person to person. Sudden changes are often harmless, but they can indicate an underlying health condition, such as irritable bowel syndrome or inflammatory bowel disease.

For some people, one bowel movement per day is normal. For others, having several bowel movements a day or one every 2 days is normal. There is no set healthful pattern.

However, significant changes in the frequency of bowel movements or the appearance of feces can indicate a problem, particularly when these changes accompany other symptoms, such as diarrhea, constipation, or abdominal pain.

In this article, we investigate what can cause changes in bowel movements and when to see a doctor. We also describe diagnosis and treatments.

Irritable bowel syndrome (IBS)

Man experiencing abdominal pain and changes in bowel habit
IBS can cause symptoms that include constipation and bloating.

IBS is a long-term condition that affects the digestive system. The medical community is unsure of the causes, but digestive problems, increased sensitivity within the gut, and other physiological factors may be involved.

People with IBS can experience a range of digestive symptoms, including:

  • abdominal cramps and pain
  • diarrhea
  • constipation
  • bloating
  • gas

Learn more about IBS here.

Crohn’s disease

Crohn’s disease is a type of inflammatory bowel disease (IBD). It can cause inflammation in any part of the digestive tract, but it most commonly affects the small intestine and the start of the large intestine, or colon.

Crohn’s is generally a lifelong condition, and symptoms can include:

  • diarrhea
  • abdominal cramps and pain
  • bloody stools
  • fatigue
  • sudden urges to have a bowel movement
  • constipation
  • weight loss

Learn more about Crohn’s disease here.

Ulcerative colitis

Ulcerative colitis is another type of IBD, and it also tends to last a lifetime. It causes inflammation and ulcers to develop along the lining of the colon and rectum.

Symptoms of ulcerative colitis can include:

  • diarrhea
  • stools that contain blood or mucus
  • abdominal cramps or pain
  • strong, frequent urges to have a bowel movement
  • fatigue
  • weight loss
  • anemia

Learn more about ulcerative colitis here.

Thyroid dysfunction

Doctor checking female patients thyroid glands
The thyroid gland is on either side of the windpipe.

The thyroid gland releases hormones to control a range of processes in the body, including growth and metabolism.

Hypothyroidism, or an underactive thyroid, occurs when the thyroid does not produce a sufficient amount of hormone.

In addition to constipation, hypothyroidism can cause:

  • fatigue
  • sensitivity to temperature
  • muscle aches and weakness
  • muscle cramps
  • thinning of the skin
  • depression
  • irregular or heavy periods

Learn more about hypothyroidism here.

Hyperthyroidism, or an overactive thyroid, occurs when the gland produces too many hormones. This can also cause a range of symptoms, including diarrhea. Others symptoms can include:

  • hyperactivity
  • extreme mood swings
  • fatigue
  • muscle weakness
  • anxiety
  • difficulty sleeping

Learn more about hyperthyroidism here.

Celiac disease

Celiac disease is a lifelong condition. It occurs when gluten in the diet causes digestive problems. Gluten is a type of protein present in wheat, rye, and barley.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, around 1 in 141 Americans have celiac disease, and most are unaware that they have it.

Doctors are unsure what causes celiac disease, but they believe it to stem from a problem with the immune system. The condition can sometimes run in families.

Symptoms of celiac disease can include:

  • diarrhea
  • abdominal cramps and pain
  • bloating
  • upset stomach
  • constipation
  • gas

Learn more about celiac disease here.

Bowel cancer

Colon, rectal, and colorectal cancer are types of bowel cancer. The name describes where the cancer first develops.

Symptoms of bowel cancer can include:

  • blood in stools
  • persistent changes in bowel habits, such as diarrhea or constipation
  • abdominal pain or cramps
  • bloating
  • fatigue and weakness
  • weight loss

It is important to note many less severe health conditions can cause these symptoms. In most cases, the cause is something other than cancer.

Learn more about bowel cancer here.

When to see a doctor

Contact a doctor if any change in bowel movements has persisted for more than a few days. Even minor changes, such as constipation or diarrhea, can indicate a health issue.

If more severe symptoms occur, consult a doctor immediately. These can include:

  • blood, mucus, or pus in stools
  • severe abdominal cramps or pain
  • severe diarrhea that lasts more than a day
  • dizziness or confusion
  • persistent nausea or vomiting


A doctor may recommend an ultrasound scan to diagnose the cause of bowel changes.
A doctor may recommend an ultrasound scan to diagnose the cause of bowel changes.

First, a doctor will review a person’s symptoms and medical history. This will include asking about the frequency and consistency of stools.

A doctor may need a blood or stool sample to help with diagnosis. For example, a blood test can indicate inflammation in the body or help rule out certain diagnoses.

A doctor may also request:

  • Imaging tests, such as X-rays, CT scans, and ultrasounds, help a doctor check the internal organs for problems.
  • An endoscopy involves inserting a thin tube with a light and camera down the throat and into the digestive tract to look for issues.
  • A colonoscopy involves inserting a thin tube with a light and camera up through the rectum to check for problems in the colon.


Treatment will depend on what is causing the bowel changes. If no cure for the underlying cause is available, a doctor will aim to relieve symptoms and prevent progression of the disease.

Treatment plans may involve:

  • lifestyle and dietary changes
  • courses of medication, which may include anti-inflammatory, immunosuppressant, or anticancer drugs
  • surgery


Everyone’s bowel habits are different, and temporary changes are usually nothing to worry about.

However, persistent or severe changes can indicate an underlying health problem, especially when additional symptoms occur. IBS, IBD, thyroid problems, celiac disease, and cancer can all cause persistent bowel issues.

If bowel-related changes last for more than a few days, contact a doctor. Seek immediate medical attention for severe symptoms, such as blood or mucus in stools, intense pain or cramping, or persistent nausea or vomiting.