context: You have Crohn's disease. Maybe you've had it for a long time, or maybe you've just been diagnosed. You've heard and read a lot about it, but you don't really know what to expect. The first thing to do is ask your doctor. He can help you understand your condition and provide answers to your questions. It's a good idea to learn all you can about it. Crohn's disease is a type of inflammatory bowel disease. That means that your body's immune system attacks and damages your bowel or gastrointestinal system. It's a chronic, meaning long-term, condition that gets in the way of your body's ability to take in important nutrients. It can also affect the way you digest food and get rid of waste. Crohn's can involve any part of your gut. But the ileum, the last part of your small intestine, is most commonly affected. Because of inflammation, you might have some of these symptoms: Diarrhea or frequent, watery bowel movements Urgent bowel movements Trouble having bowel movements Bleeding from your rectum Pain or cramping in your abdomen, or belly Weight loss Tiredness Other parts of your body, like your joints, skin, or eyes, can be affected, too. Symptoms can come and go. You may have periods of time when you feel fine. These times might be followed by flare-ups of the condition. Remission also is possible. With Crohn's, remission is sometimes thought to take place when symptoms go away and ulcers in the colon begin to heal. You should be able to do just about anything. But you may need to make some adjustments. Each person is different. Your Crohn's disease might: Affect a large part of your gastrointestinal system or only a small part Be mild, moderate, or severe Go long periods without symptoms or flare-ups Be fairly easy to control, or it may be very difficult Go into remission Depending on the way Crohn's affects you and your ability to manage it, you may have some challenges. Your symptoms. Although most people with Crohn's are able to have active lives, symptoms and flare-ups may cause you to miss work, school, or other activities - even if you stick to your treatment plan. Your day-to-day activities. You may want to plan your activities with your Crohn's in mind. For example, know where the closest bathroom is. Your diet. Stay away from some foods if they make you feel worse. For instance, if milk products or greasy foods cause diarrhea, don't eat them. Your mood. Crohn's disease, like other chronic conditions, may affect your mood. You may feel more stressed or depressed at times. You may have pain, which also affects your emotions. If your condition starts to get to you, look into seeing a counselor and joining a support group. If you're female, Crohn's could affect your ability to get pregnant. If it isn't well-controlled, it may cause problems once you are pregnant. Your doctor may recommend a C-section if you have certain complications. Crohn's causes two types of complications: Local, which involve the intestinal tract Systemic, which affect your entire body Local complications of Crohn's include: Abscess: This pocket of pus results from a bacterial infection. It can form on your intestinal wall and bulge out. Or you might get one near your anus that looks like a boil. You'd notice swelling, tenderness, pain, and fever. Bile salt diarrhea: Crohn's disease most often affects the ileum, the lower end of your intestine. This part usually absorbs bile acids, which your body creates to help it absorb fat. Fissure: Painful tears in the lining of the anus. They can cause bleeding during bowel movements. Fistula: Sores or ulcers can turn into openings that connect two different parts of your intestine. They can also tunnel into nearby tissues (bladder, vagina, skin). Malabsorption and malnutrition: The disease affects your small intestine, the part of your body that absorbs nutrients from food. After you've had it for a long time, your body may no longer be able make the most of what you do eat. Small intestinal bacterial overgrowth ( SIBO): Your gut is full of bacteria that help you break down food. When this happens higher up in your digestive tract than normal, you can get gas, bloating, belly pain, and diarrhea. Strictures: These narrowed, thickened areas of your intestinal tract result from the inflammation that comes with Crohn's. They can be mild or severe, depending on how much of your intestine is blocked. Symptoms include cramping, abdominal pain, and bloating. Systemic complications are often called extraintestinal. Some of the most common ones include: Arthritis: Joint inflammation -- which leads to pain, swelling, and a lack of flexibility -- is the most common complication. There are three types of arthritis that sometimes come with Crohn's: Peripheral: This type affects large joints in your arms and legs, like your elbows, knees, wrists, and ankles. Axial: This type affects your spine or lower back (the doctor will call it your sacroiliac joint). Ankylosing spondylitis: This more serious type of spinal arthritis is rare among people with Crohn's, but it can happen. Besides causing arthritis in your back, it can lead to inflammation in your eyes, lungs, and heart valves. Bone loss: Medications like steroids can lead to bone loss, a condition known as osteoporosis. They can: Stop your body from absorbing calcium, which your body needs to build bone Make your body get rid of calcium when you pee Boost production of cells that break down bone Lower the number of cells that help form bones Lower your body's output of estrogen. Estrogen also helps build bone. The proteins that cause inflammation change the pace at which old bone is removed and new is formed. Vitamin D deficiency. If your body can't absorb vitamin D because of Crohn's damage to the small bowel or a small bowel resection, you're less likely to be able to absorb calcium and make bone. Crohn's may also affect your body's ability to absorb other fat-soluble vitiamins, iron, and copper. Skin problems: These are the second most common systemic complication. Those most often linked to Crohn's disease include: Erythema nodosum: These small, tender, red nodules usually show up on your shins, ankles, and sometimes your arms. Pyoderma gangrenosum: These pus-filled sores often follow an injury or other skin trauma. They often appear on your legs but can show up anywhere. Skin tags: These small flaps of skin are common in people with Crohn's, especially around the anus or hemorrhoids. Mouth ulcers: You might hear them called canker sores. They form between your gum and lower lip or along the sides and bottom of your tongue. Eye problems: Over time, the inflammation from Crohn's, or sometimes the other complications that come with it, can affect your eyes. Common conditions include: Episcleritis: Inflammation of the area just below the conjunctiva (the clear tissue that covers the inside of your eyelids and the white of your eye) is the most common complication of Crohn's. It can affect one eye or both. You'll notice pain, itching, burning, and intense redness, but it won't hurt your vision. Scleritis: This condition causes a constant pain that gets worse when you move your eyes. Uveitis: This is a painful inflammation of the uvea, the middle layer of your eye. It can cause blurry vision, light sensitivity, and redness. Kidney problems: These organs can be affected by Crohn's because they play a role in processing waste and are near your intestines. Potential issues include: Kidney stones: They're a common problem with Crohn's because your body has a hard time absorbing fat. It binds to calcium and leaves a salt called oxalate that gets absorbed into your kidneys and can turn into stones. Uric acid stones: These kidney stones form due to dehydration and a process called metabolic acidosis in which the balance of acids and bases in your blood gets thrown off. Hydronephrosis: This happens when the ileum (where you small intestine meets the large) swells from Crohn's and puts pressure on your ureter, the tube that carries urine from your kidney to your bladder. When urine can't drain the way it should, your kidney swells and scar tissue can form. Fistulas: In addition to forming within your intestines, fistulas can also develop between the intestine and other organs, like the bladder or ureter. Liver problems: Your liver processes everything you eat and drink. It can get inflamed as a result of Crohn's treatment or the disease itself. You're only likely to notice low energy and fatigue unless you develop a more serious problem. Among the most common issues: Fatty liver disease: When your body doesn't process fats as well, they can build up in your liver. Steroids can help. Gallstones: Your gallbladder stores bile, a liquid that helps your body dissolve fats. When Crohn's affects the terminal ileum (where your small intestine meets the large intestine), it can't process bile salts, which help cholesterol dissolve in bile. When that happens, the cholesterol can form into stones that block the opening between the liver and the bile duct, which sends bile down to your intestines. Hepatitis: Crohn's disease can cause chronic (long-term) liver inflammation and primary sclerosing cholangitis. Pancreatitis: Inflammation of the pancreas can result from gallstones and from medications. It can cause pain, nausea, vomiting, and fever. Physical development problems: Crohn's can start at any age. When kids get Crohn's, parents are likely to notice: Growth failure: Kids with Crohn's are likely to be shorter and weigh less than those without. They may stop getting taller before symptoms start. Delayed puberty: Kids with Crohn's are likely to start puberty later than their friends. Causes include malnutrition and lower fat mass, and interactions between proteins that cause inflammation and the endocrine system, which governs hormones. Most people with Crohn's disease will have periods of disease activity followed by periods of remission. Doctors say if these things apply to you at diagnosis, your Crohn's may be more severe if you: Are younger than 40 Have perianal or rectal disease Are taking steroids first thing Smoke Have a low education level Some general facts: A small number of people will go into a long remission right after their first diagnosis. Many will get strictures or penetrating disease about 10 years after disease starts. Most will need surgery. Up to 80% of people with Crohn's will be hospitalized at some point. Most people have symptoms that come and go, but a small number will either have continuous, active disease or prolonged remission. About half the people in remission who have surgery will have a recurrence at the 5-year mark. Some people have a more aggressive form of the disease that causes recurring obstructions or perforations. These people will need more surgery. There are a lot of things to consider, like the fact that Crohn's affects everyone differently, and no two people have the exact same level of medical care. But doctors estimate that higher odds of death from Crohn's range from zero to five times that of people who don't have it.