context: Both celiac disease and irritable bowel syndrome ( IBS) can cause stomach cramps, gas, and bloating after eating certain foods. So how can you tell the difference? When you have celiac disease, your immune system reacts to foods with gluten, a protein found in grains like wheat, barley, or rye. If you have it and eat cereal, bread, or other foods that contain gluten, you can get very sick. Both kids and adults can have the disease. About 1% of people have it. Some people who don't eat gluten may be sensitive to it, but they don't have celiac disease. Symptoms: With celiac disease, you may have diarrhea, stomach cramps, gas and bloating, or weight loss. Some people also have anemia, which means your body doesn't make enough red blood cells, and feel weak or tired. You also may have acid reflux or heartburn, itchy skin rashes or blisters, numb or tingly feet or hands, joint pain, headaches, mouth sores, or damage to the enamel on your teeth. Kids with celiac disease may be more likely to vomit and have diarrhea or not be very hungry. They can get a potbelly or swollen gut, and they may have foul-smelling stool. Causes: It's not completely clear what causes celiac disease. Certain genes may make you more likely to have it. Some people only get it after pregnancy or severe stress. An infection can also trigger the disease. Long-term risks: Over time, celiac disease can damage the lining of your intestines, and your body may not be able to take in enough nutrients. You also may become lactose-intolerant and get painful gas from dairy products. If you don't get enough calcium and vitamin D from food, your bones can become weak or soft. Kids with celiac disease may not get enough food or nutrients to develop strong muscles or bones. They can lag behind other children in height and weight. About 20% of people with celiac disease who cut out gluten still have symptoms. Some of those people may also have IBS. Irritable bowel syndrome is a disorder that affects your large intestine (colon). About 10% to 15% of people have IBS. Most of them have either mild or moderate symptoms. Symptoms: IBS can cause strong stomach pain or bloating. You also may have constipation or diarrhea or both at different times. Like celiac, IBS pain can flare up after you eat. You may feel an urgent need to go to the bathroom often, and you may have mucus in your stool. Some women with IBS have attacks at different points in their menstrual cycle. They may have belly pain and diarrhea just before their period starts and in the first few days of their flow. They may tend to get gas and constipation in the middle of their cycle. Causes: Doctors don't know what causes IBS. It may be a problem in the way your brain sends signals to your gut about how to digest food. Stress doesn't cause IBS, but it can make you feel worse. Long-term risks: IBS shouldn't cause any long-term health problems. It can, though, affect your quality of life. Symptoms may come and go. If you have severe stomach pain, diarrhea, or gas right after you eat certain foods, see your doctor. Tell her when your symptoms started and what seems to trigger them. She'll probably want to do a few tests to find out what the problem is. Blood test: This may show if you have celiac antibodies or low blood counts, which is a sign of anemia. Endoscopy: Your doctor will look for damage to your small intestine through a long, lighted tube. He also might take a sample of tissue (called a biopsy) to test for signs of celiac. Bone density test: This is a low-dose X-ray that shows how much mineral is in your bones. It can predict how strong your bones are and how likely they are to break. There is no test for IBS. Your doctor will go over your symptoms to rule out other causes like celiac, Crohn's disease, or ulcerative colitis. If you don't have any of those, you probably have IBS. Whether you have celiac or IBS, diet and lifestyle changes can help. Stay away from foods that may trigger flares, and exercise to keep your muscles and bones strong. That also can ease stress. If you have celiac: Completely cut out foods with gluten. That can include things with wheat, barley, rye, spelt, malt, or triticale, and don't drink beer or ale. Grains like rice, oats, and corn or starches like potatoes should be fine. But you may need to avoid cow's milk or dairy foods if they bother you. Watch for gluten in unexpected places, like vitamins or salad dressing. If celiac disease has caused severe damage to your intestines, you may need steroids to calm the inflammation. You also might take calcium, vitamin D, or other vitamin supplements if you can't get enough nutrients from your food. If you have IBS: Figure out which foods are problems for you. You may try to follow a diet called Low FODMAP for a few weeks. This involves cutting out certain carbohydrates and then slowly adding them back to find out what bothers you. You can use laxatives or add fiber to your diet to treat constipation, and you can get loperamide ( Imodium) at your local drug store to treat diarrhea. If you need them, your doctor can prescribe drugs to treat stomach spasms or pain. Certain antidepressants also may help with the symptoms of IBS. But more research is needed to know for sure.