The symptoms of irritable bowel syndrome, or IBS, include pain in the lower abdomen, excessive gas, bloating, changes in the pattern of bowel movement and mucus in the stool, according to WebMD. These symptoms must occur repeatedly over the course of time for a diagnosis of IBS to be reached.
IBS is characterized by these symptoms occurring for at least six months, with abdominal pain occurring at least three days in every month over the course of three months and at least two of the three specific criteria being met, according to WebMD. These criteria include pain linked to changes in stool consistency or appearance, stool frequency or pain that is relieved when a bowel movement is passed.
Bowel movement patterns in IBS vary over time, notes WebMD. Sufferers of IBS experience two or more common symptoms, including diarrhea or constipation, stool that varies in consistency and size, feelings of bloating or excess gas or changes in the way that stools are passed, such as urgent feeling of going or the need to strain.
Some symptoms of IBS are not related to the gastrointestinal tract, including backache, headache, fatigue, depression and anxiety, according to WebMD. Other non-intestinal symptoms include insomnia, sexual dysfunction, urinary problems and heart palpitations.