A person may develop bloating and diarrhea in relation to a wide range of conditions. Some of the most common causes of bloating and diarrhea, however, include gastrointestinal illnesses caused by viruses, bacteria, and parasites. A person may also become bloated and suffer from diarrhea because he has a long-term condition, such as irritable bowel syndrome or Chrohn's disease. In some cases, a person may even suffer from these symptoms because he is lactose intolerant; has eaten a food that proved irritating to his digestive system; or has taken medication that caused him to have abdominal gas and loose bowels.

One of the most frequent causes of bloating and diarrhea is an acute gastrointestinal illness. An acute illness is short term, so a person with an acute gastrointestinal illness may have bloating and diarrhea for just a few days. It is also possible for an acute gastrointestinal illness to last for a couple of weeks, however. This type of illness may be caused by a range of viruses, bacteria, or parasites and is often referred to as a stomach virus.

Sometimes the cause of bloating and diarrhea is a long-term condition, which is often referred to as chronic. One type of chronic condition a person may develop is called irritable bowel syndrome. It is marked by abdominal cramping, bloating, diarrhea, and the passage of gas. Chrohn’s disease may cause a person to suffer not only bloating and diarrhea, but also blood in the stool, mouth sores, and intestinal ulcers.

An individual may also develop bloating and diarrhea because he is lactose intolerant or taking a medication that causes diarrhea and gas. If an individual is lactose intolerant, he cannot digest lactose, which is a type of natural sugar found in dairy products. When he does consume dairy products, he may develop diarrhea, bloating, and nausea. Additionally, there are some medications that have diarrhea and bloating as a side effect.

In the case of acute diarrhea, a person may have to let it run its course, as taking medication to stop it could allow the virus, bacterium, or parasite that caused it to build up in the body. Chronic gastrointestinal conditions, however, are often treated with prescription medications and dietary changes. People with lactose intolerance may take supplements that help them digest dairy products or consume special dairy products that do not contain lactose.