It’s easy to get irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) mixed up.

Both are chronic conditions that cause abdominal pains, cramping, and urgent bowel movements. But despite having similar acronyms and symptoms, these two conditions are very different.

IBS is a disorder of the gastrointestinal (GI) tract. IBD is inflammation or destruction of the bowel wall, which can lead to sores and narrowing of the intestines. It’s possible to have both IBD and IBS.

To help understand the difference between IBS and IBD, we spoke with two physician researchers in gastroenterology.

IBS affects the lower GI area, which includes the small intestine, large intestine, and colon.

Patients with IBS experience chronic diarrhea, constipation, and in some cases both.

For years, IBS patients have complained to doctors about being gassy, bloated, and constipated. Many were dismissed or told they were stressed out or needed psychological interventions, not medical treatment.

"It's a disease," says Dr. Mark Pimentel, director of Cedars-Sinai's GI Motility Program. "And even the terminology, irritable bowel syndrome, is marginalizing the patients who have the condition."

Up to 70% of IBS patients have experienced severe food poisoning, which Dr. Pimentel believes is the primary cause of the disease.

"For about a third of the patients who get IBS, it's a one-and-done treatment with antibiotics," says Dr. Pimentel, who pioneered the use of the drug rifaximin to treat IBS.

"But in order for many other patients to get better, you have to re-treat and re-treat the disease because those symptoms keep coming back."

Those treatments could include antibiotics, diet changes, and sometimes medication to ease constipation or diarrhea.

Many IBS patients have suffered without treatment because they've been told the condition is in their heads, but it's now easy to diagnose IBS with a simple blood test developed by Dr. Pimentel.

IBD causes inflammation of the intestines. IBD is a term for a broad spectrum of diseases, but Crohn's disease and ulcerative colitis are the most common.

For many patients, IBD is genetic, but no single gene has been shown to cause IBD.

"How severe the disease is depends on a combination of genetic abnormalities and the effects of any number of microbes on the immune system," says Dr. Stephan Targan, director of Cedars-Sinai's Inflammatory Bowel Immunobiology Institute.

Like IBS, the most common symptom of IBD is diarrhea. Other symptoms include abdominal cramps, bloody stool, blocked bowels, fever, loss of body fluids and appetite, extreme weight loss, and anemia.

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Diagnosing IBD is complex and can take months. After a patient's medical and family history is collected, they're given a physical exam, laboratory tests, and a variety of endoscopic procedures.

Blood tests developed by Dr. Targan can help doctors differentiate between the forms of IBD and optimize treatments.

Sometimes MRI and CT scans are used to confirm diagnosis and determine how much of the intestine is affected by IBD.

Because IBD is a chronic condition, an important part of treatment involves careful management of the disease so that patients have the best chance of controlling their symptoms.

Patients may need antibiotics, antidiarrheal drugs, lifestyle changes, and depending on the severity of the disease, sometimes surgery.

Millions of people suffer from IBS or IBD. If you think you may have IBS or IBD, see a gastroenterologist about your symptoms. Relief is available.