The muscle movement that passes food through the digestive tract (especially the colon) is called motility. When you have IBS, this movement is disrupted. Motility may speed up, slow down, or become irregular. If stool passes too quickly through the colon, not enough water is absorbed from it. You may have loose, watery stools (diarrhea). If stool passes through the colon too slowly, too much water is absorbed and the stool becomes hard and dry. You may then have constipation. Also, stool and gas may back up. This can cause painful pressure and cramping.

In part, IBS is also a problem of increased sensation. Sensations in the digestive tract may set off pain in IBS. They would not do so in someone without IBS.

No single test can diagnose IBS. Your healthcare provider will ask about your symptoms. You may also have blood, stool, or radiologic tests. You may even need a colonoscopy. These tests are done mainly to rule out other concerns. 

Lots of research has been done on IBS. But the cause is still not fully known. Some of the possible factors are: 

• Smoking, eating certain foods, drinking alcohol, or caffeinated drinks can cause, or "trigger," symptoms of IBS.

• IBS may be caused by a problem with the nerves or muscles in your digestive tract.

• Some evidence suggests that certain bacteria found after a severe gastrointestinal infection in the small intestine and colon may cause IBS.

• Stress and anxiety tend to make the symptoms of IBS worse. But it is not believed to be the primary cause. 

Medicine can’t cure IBS, but it may help manage the symptoms. It may help your digestive tract work better. Your healthcare provider may prescribe one or more medicines for you. Because some medicines may make IBS worse, don’t take any medicine, especially laxatives, unless your healthcare provider prescribes it for you.

Your healthcare provider may also suggest some lifestyle changes to help control your IBS. You may have to change your diet and learn to better manage your stress. Yoga and mindfulness have been shown to ease IBS symptoms. Dietary changes can also be helpful. If diet changes are advised, talk with a dietitian. They can help you keep a healthy nutritional balance in your food intake. 

Your diet may be an important cause of IBS symptoms. You may want to try the following:

• Pay attention to what foods bother you, and stay away from them. For example, dairy products are hard for some people to digest. Lactose-free dairy products may be better for your symptoms.

• Don't eat high FODMAP foods. Common foods that can cause symptoms have carbohydrates called FODMAPs. Your body can't digest these well. High FODMAP foods include some fruits, such as apples, vegetables, such as cabbage, and some dairy. They also include certain sweeteners, such as high-fructose corn syrup, sorbitol, and xylitol. Many people find that eating a diet low in FODMAPs can ease symptoms. Talk with your healthcare provider about a low FODMAP diet.

• Drink 6 to 8 glasses of water a day.

• Don't have caffeine or tobacco. These can affect how your digestive tract works.

• Don't drink alcohol. It can irritate your digestive tract. It can make your symptoms worse.

• Eat more fiber if constipation is a problem. Fiber makes the stool softer. That makes it easier to pass through the colon.

• Eat more fiber if diarrhea is a problem. Fiber also helps to bind water. This can help to firm up loose stool.

  

Learn how to manage stress if stress or anxiety makes your IBS symptoms worse. Managing stress may help you feel better. Try these tips:

• Find out what causes stress in your life.

• Learn new ways to cope with them. Mindfulness, meditation, and yoga may help.

• Regular exercise is a great way to ease stress. It can also help ease constipation. For adults, the CDC recommends 150 minutes of moderate activity each week. Or you can get 75 minutes of vigorous activity each week. It also advises muscle-strengthening activities 2 days a week. If this sounds like a lot of time, the CDC suggests breaking physical activity into 10-minute blocks. You can spread those out over a week. Developing a schedule that works for you is the key to a successful exercise program.