Common digestive issues include constipation, diarrhea, bloating, and the feeling of an unfinished bowel movement. These are often symptoms of different digestive disorders, such as irritable bowel syndrome (IBS), ulcerative colitis (UC), and Crohn’s disease.

Digestive issues such as diarrhea, bloating, and constipation are very common. There are a number of reasons why a person may be experiencing them.

In this article, we outline several conditions that may cause digestive issues and list their symptoms and causes.

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IBS is a common condition that affects the digestive system.

According to the American College of Gastroenterology (ACG), IBS affects an estimated 10–15% of people in the United States, but only 5–7% of adults have received a diagnosis.

Symptoms of IBS

Common symptoms of IBS include:

  • abdominal pain
  • diarrhea
  • constipation
  • bloating
  • feelings of unfinished bowel movements
  • white mucus in the stool

A person with IBS may experience these symptoms without having any damage or disease in their digestive tract.

IBS symptoms can appear in flare-ups, which can last for several days. Between flare-ups, a person may experience periods of remission, during which they have no symptoms at all.

Causes of IBS

The causes of IBS are unclear. Some experts believe that microbial factors play a role in the development of the disorder.

According to one 2017 review of 45 studies, just over 10% of people who experience food poisoning develop IBS later in life.

Experts also believe that problems with the way the brain and the gut interact can affect how the digestive system works and may cause IBS symptoms.

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the following problems are common in people with IBS and may cause IBS symptoms:

  • stressful early life events, including physical or sexual abuse
  • depression, anxiety, and somatic symptom disorder
  • bacterial infections in the digestive tract
  • food intolerances or sensitivities to certain foods

SIBO is a common gastrointestinal (GI) disorder.

The large intestine tends to have higher levels of bacteria than the small intestine. This is because gastric acid secretion and intestinal motility limit the overgrowth of bacteria within the small intestine.

If these two protective mechanisms against excessive bacterial growth stop working, a person may develop an excess amount of bacteria in their small intestine.

Symptoms of SIBO

SIBO symptoms are similar to the symptoms of other digestive disorders, including IBS and lactose intolerance.

Common symptoms of SIBO include:

  • stomach pain
  • bloating
  • diarrhea
  • constipation
  • nausea
  • unintentional weight loss

Causes of SIBO

An imbalance of bacteria in the small intestine causes SIBO.

Excessive bacteria can develop after bacteria travel to the small intestine from another part of the GI tract or when naturally occurring bacteria in the small intestine multiply.

Acid reflux occurs when acid from a person’s stomach rises into their esophagus.

If a person experiences acid reflux regularly, they may have GERD.

According to the ACG, GERD is one of the most common GI diseases and affects an estimated 20% of people in the U.S.

Symptoms of GERD

The main symptom of GERD is heartburn. This is a feeling of discomfort or a burning sensation in the chest.

Heartburn can become worse if a person lies down or bends over. It may also become worse after a person has eaten.

Other symptoms of GERD include:

  • nausea
  • vomiting
  • bad breath
  • respiratory problems
  • difficulty or pain when swallowing
  • tooth decay

Causes of GERD

Occasional acid reflux is common. However, if this issue occurs frequently, a person may have GERD.

The main cause of GERD is the weakening of the sphincter at the bottom of the esophagus. When this becomes weak, it opens when it should not. This allows stomach acid to rise into the esophagus.

Common factors that can cause the sphincter at the bottom of the esophagus to weaken include:

If a person has a hiatal hernia, they are also at increased risk for developing GERD. A hiatal hernia can cause the opening in the diaphragm to allow the upper part of the stomach to move into the person’s chest.

UC is a form of inflammatory bowel disease (IBD). It is a chronic, long-term condition that causes inflammation in the colon.

If a person has UC, abnormal reactions of the immune system cause inflammation in the colon. UC may also cause ulcers to form.

A person may develop UC at any age. However, it typically develops in people ages 15–30 years.

Symptoms of UC

UC symptoms can vary from person to person. Around half of people with UC experience mild symptoms.

UC often causes digestive issues. Common digestive symptoms include:

  • the urge to have bowel movements when the bowel is empty
  • loose bowel movements
  • bloody stools
  • abdominal cramps and pain
  • diarrhea

UC symptoms often appear in flare-ups. Flare-ups often occur between periods of remission. When a person is in remission, they may experience very few symptoms or no symptoms at all.

If a person has UC, they may also experience symptoms unrelated to their digestion. These include:

  • fever
  • fatigue
  • loss of appetite
  • weight loss
  • nausea
  • low red blood cell count (anemia)
  • delayed growth and development in children

Causes of UC

UC is an immune disorder. This means that a person’s immune system attacks the body’s own cells.

If a person has UC, their immune system attacks cells in the colon, causing inflammation. This may also cause ulcers to form. The inflammation and ulcers then cause symptoms of UC to develop.

Medical professionals do not entirely know what causes this abnormal immune response. However, experts believe that the following factors may increase a person’s risk of developing UC:

  • Genetics: Sometimes UC occurs in families, so having a close relative with UC may increase a person’s risk of developing it.
  • Microbiome: Certain bacteria, viruses, and fungi in the digestive tract may increase a person’s risk of developing UC.
  • Environmental factors: Environmental factors such as diet, smoking, and air pollution may influence a person’s chances of developing UC.

Crohn’s disease is a form of IBD. An abnormal immune response causes inflammation to occur in a person’s digestive tract.

Crohn’s disease can cause inflammation in any part of the GI tract, including the esophagus, stomach, small intestine, and colon.

It affects an estimated 3 million people in the U.S.

Symptoms of Crohn’s disease

Crohn’s disease can cause a number of GI symptoms, including:

  • diarrhea
  • rectal bleeding
  • the urgent need to have bowel movements
  • abdominal cramps
  • abdominal pain
  • the sensation of an incomplete bowel movement
  • constipation

Symptoms of Crohn’s disease often appear in flare-ups between periods of remission. When in remission, a person may not experience any symptoms at all.

Crohn’s disease may also cause a person to experience symptoms unrelated to their GI tract. These include:

  • anemia
  • red eyes
  • painful eyes
  • fatigue
  • fever
  • joint pain or soreness
  • nausea
  • loss of appetite
  • skin changes, such as discolored, tender bumps under the skin

Causes of Crohn’s disease

Like UC, Crohn’s disease is an immune disorder that causes the immune system to attack the body’s own cells.

Common factors that can increase a person’s risk of developing Crohn’s disease include:

  • Genetics: If a person has a parent or a sibling with Crohn’s disease, it increases their risk of developing the disease.
  • Smoking: Smoking can more than double a person’s chances of developing Crohn’s disease.
  • Diet: A high-fat diet may increase a person’s risk of developing Crohn’s disease.
  • Medications: Some medications, such as NSAIDs, antibiotics, and birth control pills, may slightly increase a person’s chance of developing Crohn’s disease.

If a person has a food intolerance, they find it difficult to digest certain foods.

Food intolerances are different from food allergies. A food allergy involves the immune system reacting to a specific food, but a food intolerance usually involves issues with the digestive system, not the immune system.

Symptoms of food intolerances

Food intolerances affect people differently. Common GI symptoms of food intolerances include:

  • bloating
  • excess gas
  • stomach pain
  • diarrhea
  • constipation

Specific food types can trigger symptoms. The severity of the symptoms can depend on how much of the trigger food a person has eaten.

Other non-GI related symptoms of food intolerances include:

Causes of food intolerances

Food intolerance often arises due to the body’s inability to digest certain foods. This may be due to a lack of specific digestive enzymes or the body’s sensitivity to certain chemicals.

Common food intolerances include:

  • milk and dairy products
  • gluten
  • fructose
  • food colorings and preservatives
  • sulfites
  • other compounds, such as caffeine and fructose

A number of other conditions may cause GI issues. These include:

There are several common digestive issues a person may experience. These include diarrhea, constipation, bloating, and the feeling of an unfinished bowel movement.

Several conditions can cause these problems to arise. Common digestive disorders include IBS, SIBO, GERD, UC, Crohn’s disease, and food intolerances.

A person may also experience digestive issues as a result of other conditions, including cancers, viral infections, bacterial infections, food poisoning, and hormonal diseases.