IBS stands for irritable bowel syndrome and may not cause any harm to your body but sometimes causes a lot of discomfort. It isn't known exactly what causes IBS, but it is thought it may be due to various factors affecting the nervous system and microbiome of the bowels. The symptoms can range from mild to severe. There is no cure for IBS but some simple lifestyle changes and treatments usually make the symptoms much better.
This is a companion discussion topic for the original article at https://patient.info/digestive-health/irritable-bowel-syndrome-leaflet