The symptoms of IBS can vary quite a bit from person to person. The main symptoms are abdominal pain, cramping, and bloating, but some people tend to have a lot of gas as well. Other common symptoms include mucus in the stool, diarrhea, and constipation. Diarrhea is characterized by frequent, loose, watery stools while constipation refers to hard, difficult-to-pass or infrequent stools. Some people tend to have primarily constipation along with the other symptoms of IBS while others tend to have diarrhea instead. A third group of people with IBS tends to alternate between having diarrhea and having constipation.

IBS is usually a chronic condition, meaning the symptoms tend to recur over and over again. However, the severity of those symptoms is also variable between different people. Many people have only mild symptoms and may experience long stretches of months or more without any symptoms at all. Other people have severe, disabling symptoms and may report a constant worsening of their symptoms over time.