Bile is a digestive fluid created in the liver and held in the gallbladder for use in breaking up fat during digestion. It may be yellow or green when expelled, making it fairly easy to identify in vomit. There are many reasons why a person may begin throwing up bile, including a lack of anything else to purge after multiple vomiting episodes have left the stomach empty. Other reasons range from irritation to obstructions and surgery.

Vomiting bile because the stomach is empty from multiple recent vomiting episodes may not be as serious as some reasons behind throwing up bile. It often is the defense-mechanism result of a stomach virus or other illness. That's not to say multiple vomiting episodes are nothing to fret. A person suffering from nausea and vomiting should be sure to stay well hydrated and may need to consult a doctor if vomiting persists.

When a person has an obstruction in his small intestine, it can cause bile to be expelled. Bile is naturally mixed in with the stomach contents but, once an obstruction is present, the bile can be forced out by vomiting. Some causes of small intestinal obstructions are adhesions, gallstones and inflammatory bowel disease.

Another cause of throwing up bile is bile reflux, a disorder similar to acid reflux — except bile comes up instead of acid. When there is too much bile in the stomach, the body naturally wants to get rid of it and responds by vomiting. Bile reflux can be caused by peptic ulcers and gastric surgeries such as gallstone removal. Any stomach surgery, including gastric bypass, and surgeries such as having one's gallbladder removed can cause excess bile to build up in the stomach.

Drugs and alcohol can also be the cause if someone is throwing up bile. If alcohol is consumed in large quantities and for long periods of time, the stomach lining begins to get irritated. When the stomach lining gets irritated, bile is expelled. Certain drugs, such as morphine and digitalis, cause the chemoreceptor trigger to fire. Bile also will be expelled if this happens.

Cyclic vomiting syndrome (CVS), another reason for throwing up bile, happens when a person violently throws up even if he is healthy. These bouts of vomiting can last from one to 10 days. A patient who has CVS will see vomiting episodes more than once a month. The excess vomiting irritates the stomach and more bile is produced. The bile is then thrown up so the stomach can rid itself of the excess.

When bile is thrown up, it is an indication of a problem and a doctor should be contacted. Telling a doctor about the problem will help the patient get a diagnosis. Once diagnosed, the patient can be treated for throwing up bile.