What causes IBD? Here’s what an expert needs you to know.

It can be overwhelming to receive a diagnosis of inflammatory bowel disease (IBD), a condition which refers to the chronic diseases that can cause inflammation in your gastrointestinal (GI) tract. From abdominal pains to diarrhea, the symptoms of IBD can leave you feeling like you always need to stay in close proximity to a bathroom.
Today, IBD is estimated to affect 2.4 to 3.1 million Americans, although its prevalence is growing, according to the U.S. Centers for Disease Control and Prevention. Who’s at risk for developing IBD, and what are the warning signs? Here’s everything you need to know.
IBD is an autoimmune disease that prompts your body’s immune system to mistakenly attack healthy cells in your bowel, leading to inflammation, per the CDC. 
Crohn’s disease and ulcerative colitis are the main types of IBD. They’re both grouped under the same term because of the many commonalities they share, including how the two diseases manifest, their underlying mechanisms, and approaches to treatment, says Dr. Gil Melmed, MD, the director of Inflammatory Bowel Disease Clinical Research at Cedars-Sinai, and the associate director of the Division of Gastroenterology and Hepatology at Cedars-Sinai. 
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There are some key differences between Crohn’s disease and ulcerative colitis. Crohn’s disease can affect any part or layer of the bowel (from the mouth to the anus). When someone has Crohn’s disease, healthy areas of the intestinal tract live side by side to areas experiencing chronic inflammation. Distinctly, inflammation caused by ulcerative colitis is solely concentrated to the colon’s innermost lining, according to UCLA Health. 
While the exact causes of IBD are still unknown, the condition is likely the result of an interaction between your genetics and your environmental exposures, Melmed tells USA TODAY. 
By and large, people with multiple family members who have IBD are going to be most at risk for developing it. However, IBD is not a purely genetic condition, and even if you have multiple family members who have it, there’s no guarantee that you’ll develop it, Melmed says. 
Potential environmental risk factors that have been linked to IBD in genetically susceptible individuals include the use of antibiotics and other medications, pollution, hygiene, diet and climate, according to the Crohn’s and Colitis Foundation. Smoking is a risk factor particular to Crohn’s disease, says Melmed.
You can develop IBD at any age, although the median age of onset is in the late 20s, adds Melmed. Today, there is no cure for Crohn’s disease or ulcerative colitis.
According to the CDC, people with IBD often experience symptoms that come and go. During an IBD “flare-up,” symptoms may include:
In particular to ulcerative colitis, diarrhea is commonly accompanied by rectal bleeding, says Melmed. If symptoms of IBD persist, it’s important that you reach out to your healthcare provider.
While the primary symptoms of IBD relate to the gut, IBD symptoms could also involve other parts of the body, Melmed adds. These symptoms, known as extraintestinal manifestations, occur in organs outside the GI tract, such as the eyes, skin or liver, he explains. 
Because IBD can also affect children, timely diagnoses are absolutely crucial, Melmed says. Sometimes, the only warning sign of IBD in children could be that they’re falling off their growth curve, both in terms of height and weight, he says.
IBD isn’t to be confused with irritable bowel syndrome (IBS). While IBD and IBS share overlapping symptoms, the mechanisms that drive the two conditions are completely different. IBD is distinctly a disease of inflammation in which the immune system is overactive, whereas IBS “is not a condition driven by inflammation. It’s an irritable bowel,” Melmed says.
When someone has IBS, there’s a problem with bowel mobility, meaning “the bowel is actually responding to its environment by moving too fast or too slow,” Melmed explains. Usually, this could be a response to diet or stress. Some of the symptoms linked to IBS include abdominal pain, diarrhea or constipation, he says.
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The reason why it’s so important to distinguish between IBD and IBS is because the treatment for each condition requires totally different approaches. “We deal with the condition of IBD, driven by inflammation, by using medications that dampen inflammation,” Melmed says. Because IBS is not being triggered by an overactive immune system, those with GI abdominal symptoms will be treated symptomatically, he says.