Symptoms range from mild to severe. Most people have mild symptoms. IBS symptoms may be worse in patients who also have stress or mood disorders, such as anxiety and depression. However, it is important to understand that these conditions do not cause IBS.

Symptoms may include:

• Abdominal distention
• Abdominal fullness, gas, bloating
• Abdominal pain that:
  • Comes and goes
  • Is reduced or goes away after a bowel movement
  • Occurs after meals
• Chronic and frequent constipation, usually accompanied by pain
• Chronic and frequent diarrhea, usually accompanied by pain
• Emotional distress
• Depression
• Loss of appetite

Most of the time, your doctor can diagnose IBS with few or no tests. Tests usually reveal no problems. Some experts recommend a lactose-free diet for 2 weeks to evaluate for possible lactase deficiency.

Some patients may need an endoscopy, especially if symptoms begin later in life. Younger patients with persistent diarrhea may need this test to look for inflammatory bowel diseases that can cause similiar symptoms, such as Crohn's disease or ulcerative colitis. You may need additional tests if you have blood in your stool, weight loss, signs of anemia, or you have recently traveled.

Patients over age 50 should be screened for colon cancer.