Celiac disease is a lifelong (chronic) condition that occurs when gluten triggers an abnormal immune system response that damages the small intestine. Tiny, fingerlike tissues (villi) line the small intestine. The villi create a large surface that absorbs vitamins, sugars, and other nutrients as food passes through the small intestine.

When a person with celiac disease eats gluten, the villi flatten out and the intestinal lining becomes inflamed. This decreases the area in the intestine that can absorb nutrients. In some cases, the inability to absorb nutrients (malabsorption) may be severe enough to stunt growth and weaken bones. The loss of vitamins and minerals may lead to illnesses such as iron deficiency anemia, folic acid deficiency anemia, rickets, or osteoporosis.

People with celiac disease may have periods when their symptoms seem worse. Symptoms may sometimes not be noticed at all.

Celiac disease in children

In some children, symptoms begin shortly after introducing cereal into the diet, usually after 6 months of age.

A child who has celiac disease may not grow and gain weight normally because the child's body is not absorbing needed vitamins and other nutrients. Children who have untreated celiac disease can become very ill. They may need hospitalization for treatment with fluids and medication to restore nutrients. These treatments are usually short-term, and most children recover completely.

As children who have celiac disease grow into adulthood, they may be at a slightly increased risk for developing cancer (lymphoma) in the small intestine, the mouth, or esophagus, although the evidence for this is not clear. However, one study has found that following a gluten-free diet for 5 years lowers the risk for lymphoma to that of the non-celiac population.³ Even if a child with celiac disease does not have symptoms after eating gluten, it is critical that he or she stay on a lifelong gluten-free diet to avoid intestinal damage.

Although a gluten-free diet relieves symptoms and promotes the health of the intestines, children may not reach their full height if prolonged lack of nutrient absorption stunted their growth before treatment began.

Celiac disease in adults

Many adults who have celiac disease do not have any symptoms, or they have only mild symptoms. Symptoms may occur at any age but most commonly develop during the 20s, 30s, and 40s.

Adults who have celiac disease have a slightly higher-than-average risk of lymphoma, which usually develops in the intestine. They also may have a slightly increased risk of developing cancer of the esophagus.

You are likely to get better if you consistently and permanently follow a gluten-free diet. About 70% of people find their symptoms improve within 2 weeks of beginning a gluten-free diet.⁴ After the villi return to normal, which usually takes several months to several years, the body can absorb nutrients properly. Maintaining a gluten-free diet even when symptoms disappear is very important. Doing so usually prevents symptoms from returning and reduces the risk for complications of celiac disease, which may include lymphoma.