Crohn’s disease is an inflammatory condition that can affect any part of the digestive tract.

Most people with Crohn’s disease experience some inflammation in both the small intestine and the colon (large intestine), which moves stool to the rectum. (1)

The exact nature of Crohn’s disease symptoms are different in each person. Even in the same person, symptoms are likely to vary over time. (2)

Factors that can affect Crohn’s disease symptoms include what areas of the digestive tract are involved, whether your Crohn’s is responding well to your treatment, and how long you’ve had the disease. (2)

What Are the Signs of Crohn’s Disease?

Symptoms of Crohn’s disease can vary widely from person to person, depending on the areas of the digestive tract that are affected and the severity of the inflammation. (2,3)

Symptoms affecting the digestive tract may include:

Persistent diarrhea
Rectal bleeding
Abdominal cramping and pain
Nausea or loss of appetite
Urgent need to defecate
Constipation

General symptoms of Crohn’s disease often include:

Weight loss
Fever
Fatigue

Crohn’s disease can also cause symptoms in other parts of the body:

Joint pain or soreness
Red, painful, or itchy eyes
Red, tender, or bumpy skin
Disruption of menstrual cycle in women

What Are the Five Types of Crohn’s Disease?

There are five typical ways that Crohn’s disease affects the digestive tract, each with its own set of symptoms.

Ileocolitis If you have ileocolitis — the most common form of Crohn’s disease, which affects the end of the small intestine and the colon — you’re likely to experience diarrhea and pain in your lower right or middle of your abdomen. You may also experience significant weight loss with this form of Crohn’s. (1)

Ileitis Symptoms of ileitis — which affects just the end of the small intestine — tend to be similar to those of ileocolitis.

Gastroduodenal Crohn’s Disease If you have gastroduodenal Crohn’s disease — which affects the stomach and beginning of the small intestine — you’re likely to experience a reduced appetite, weight loss, and nausea or vomiting.

Jejunoileitis If you have jejunoileitis — which affects the upper half of the small intestine — you’re likely to experience abdominal pain, cramping, and diarrhea following meals.

Crohn’s Colitis If you have Crohn’s colitis — which affects only the colon — you’re likely to experience diarrhea, rectal bleeding, and sores around your anus. You’re also more likely to experience skin lesions and joint pains if you have Crohn’s colitis. (1)

How Do You Know if You Have Crohn’s Disease?

Your doctor will most likely use your medical history, a physical exam, and a series of tests to diagnose Crohn’s disease and rule out other conditions that may cause similar symptoms. (4)

Conditions with symptoms that can be similar to those of Crohn’s disease include:

Irritable bowel syndrome (IBS)
Lactose intolerance
Ulcerative colitis (an inflammatory condition similar to Crohn’s disease)

During a physical exam, your doctor will probably check for bloating, swelling, and painful or tender spots in your abdomen. (5)

Your doctor may also perform or order the following tests for Crohn’s disease.

Blood Tests Your doctor may check for anemia (inadequate red blood cells) or look at your white blood cell count, which may indicate inflammation or infection somewhere in your body if it’s elevated.

Certain blood tests may also help rule out other conditions.

Stool Tests Your doctor may find it useful to see if any blood is present in your stool, or to check for other irregularities that could indicate a digestive disease other than Crohn’s.

To perform this test, your doctor will give you a container to catch and store your stool sample. You’ll then return it to your doctor or send it by mail to a lab.

Colonoscopy Your doctor will insert a thin, flexible tube containing a camera (called a colonoscope) into your rectum and pass it into the colon to look for abnormalities.

You’ll be sedated for this procedure. During the procedure, your doctor may take a series of biopsies (small tissue samples) from inside your colon to view under a microscope.

Before having a colonoscopy, you’ll need to follow procedures to empty your bowel, which typically means drinking a laxative solution and not eating for a specified period of time.

Upper GI Endoscopy After you are sedated, your doctor will insert a flexible tube containing a camera (called an endoscope) down your throat and esophagus and into your stomach and the upper part of your small intestine.

Enteroscopy This procedure is similar to an endoscopy, but your doctor may opt for this approach to look even further into the small intestine. An enteroscopy utilizes a longer tube and some special equipment to advance the instrument deeper into the intestine.

Wireless Capsule Endoscopy You’ll swallow a capsule (about the size of a large vitamin) containing a tiny video camera that allows your doctor to see abnormalities throughout your digestive tract.

Magnetic Resonance (MR) Enterography This test provides very detailed views of the small intestine to look for inflammation, bleeding, obstructions, or other issues. (8)

Imaging Tests Your doctor may perform other imaging tests, such as an X-ray or computerized tomography (CT) scan, to look for abnormalities that might be missed in an upper GI endoscopy or colonoscopy, or if there are reasons not to perform these procedures.

What Causes Crohn’s Disease?

Scientists do not yet know what causes Crohn’s disease, but they have some theories.

One possible cause of Crohn’s is an autoimmune reaction, in which the immune system attacks the body’s healthy cells. Doctors think bacteria in the digestive tract could mistakenly trigger an immune system response, which could cause inflammation and lead to Crohn’s symptoms.

Genetics may also play a role. Research has shown that individuals with a parent or sibling with Crohn’s disease are more likely to be diagnosed themselves. (3)

Crohn’s Disease in Children

Crohn’s disease can develop at any age, but it’s typically diagnosed between age 10 and 40. (6)

Research studies have estimated that about 20 percent of Crohn’s disease cases are diagnosed in children younger than 18. (6)

In rare cases, Crohn’s disease can be caused by immune deficiencies in children younger than 5, including babies. (6)

Children typically experience symptoms similar to those of adults.

The most common Crohn’s disease symptoms in children are:

Abdominal pain
Diarrhea
Weight loss

Children with Crohn’s disease may experience some additional complications that don’t affect adults, including:

Delayed puberty — in some cases, this is the predominant or even only sign
Slow growth rate (about one-third of children with Crohn’s disease will have a shorter-than-expected adult height) (7)