Irritable bowel syndrome (IBS) is an intestinal disorder that affects people of all ages, including children. People with IBS may experience abdominal pain and/or cramping accompanied by symptoms such as gas, bloating, diarrhea and constipation. Although IBS does not pose a serious health threat, it can be distressing to children who may be embarrassed by its symptoms.

There are similar rates of IBS in children and adults, and many adult patients recognize that symptoms began during childhood. Between 6 and 14 percent of adolescents are diagnosed with IBS, according to the International Foundation for Functional Gastrointestinal Disorders (IFFGD).

During normal digestion, wave-like muscle contractions (peristalsis) within the intestines occur a few times each day, helping to move contents through the digestive tract before they are expelled as waste through the anus. Muscles, nerves and hormones work together to create peristalsis, which maintains normal digestion.

For children with IBS, nerves and muscles in the large intestine may be hypersensitive and can suddenly and involuntarily contract (spasm), speeding digestive content through the intestines and causing diarrhea. Intestinal muscles may also temporarily stop contracting, preventing content from moving forward and causing constipation.

IBS is considered a functional disorder because it involves the failure of the large intestine to function as it should. It is not a disease, since no identifiable physical abnormality or intestinal damage can be found in children with IBS. IBS is a chronic condition, in which symptoms can recur throughout a person’s life. Many, but not all children with IBS, have the condition as adults.

Functional problems that appear to be involved in IBS include:

• Increased sensitivity of the large intestine. In children with IBS, the large intestine appears to react strongly to stimuli (e.g., anxiety, stress, certain foods) that do not bother most people. Intestinal nerves may perceive the normal sensations of gas or movement of stool through the digestive tract as excessive and painful.
  
  
• Rapid or delayed transit of stool. In children with IBS, stool may travel too quickly or in too large an amount for fluid to be properly absorbed by the intestines. Too much liquid in stool causes diarrhea. Slowed movement of stool can lead to too much fluid being absorbed, resulting in constipation.
  
  
• Abnormal muscle contractions. Intestinal muscles may spasm or temporarily stop contracting. Children with IBS may experience strong contractions that can cause cramping and push stool through the digestive tract too quickly, leading to diarrhea. Spasms may trap gas or stool in one area, leaving it unable to move forward, which can cause cramping, constipation and abdominal pain. This may not occur in all children with IBS. It is unclear whether this is a cause or symptom of IBS.

The immune system may also be involved in the development of IBS. In some cases, the condition may occur after severe gastrointestinal (GI) infections such as salmonella or Campylobacter pylori.

IBS does not cause permanent physical harm to a child. Very few children with IBS are later diagnosed with some other GI condition. In addition, children with IBS tend to live as long as those in the general population. Although IBS can be embarrassing and inconvenient for children, it does not have to negatively impact their quality of life. With proper treatment, children with IBS can live a normal lifestyle.