Coeliac disease is an immune reaction to gluten that damages the small bowel. It is diagnosed with a blood test and usually a gastroscopy, both while you are still eating gluten. A strict, lifelong gluten-free diet allows the bowel to heal and prevents complications.

What is it?

In coeliac disease, eating gluten (a protein in wheat, barley and rye) causes the immune system to attack the lining of the small bowel. The finger-like villi that absorb food become flattened, so nutrients such as iron, calcium, vitamin D and folate are poorly absorbed. It is an autoimmune condition, not a food allergy and not simply intolerance.

Who gets it?

• It can start at any age, from childhood to old age
• It runs in families: up to 1 in 10 close relatives (parents, brothers and sisters, children) are also affected
• It is more common in people with type 1 diabetes, autoimmune thyroid disease, Down syndrome, and some other autoimmune conditions

Symptoms

Symptoms vary widely, and some people have none:

• Diarrhoea, bloating, abdominal pain or constipation
• Tiredness and iron-deficiency anaemia that does not respond to iron tablets
• Weight loss, or poor growth in children
• Mouth ulcers, an itchy blistering skin rash (dermatitis herpetiformis)
• Thin bones (osteoporosis), raised liver enzymes, fertility problems

Diagnosis

• You must keep eating gluten until testing is complete. Going gluten-free beforehand can make the tests falsely normal
• Blood test: tissue transglutaminase antibody (tTG-IgA), with a total IgA level
• If the blood test is positive, adults usually have a gastroscopy with small biopsies from the duodenum to confirm the diagnosis
• If you have already stopped gluten, your doctor may ask you to reintroduce it for about six weeks before testing

Treatment: the gluten-free diet

There is no medicine that replaces the diet. A strict, lifelong gluten-free diet is the treatment, and a dietitian's help at the start is strongly recommended.

• Avoid: wheat (including bread, khubz, pasta, couscous, semolina, bulgur, freekeh), barley, rye, and foods made from them
• Naturally gluten-free: rice, corn, potato, millet, fresh meat, fish, eggs, milk, laban, fruit, vegetables, legumes, dates
• Oats: pure oats labelled gluten-free are tolerated by most people once the disease is controlled; introduce them with your team's advice
• Watch for hidden gluten: stock cubes, sauces, spice mixes, some medicines and supplements, and asafoetida (hilteet), which is often mixed with wheat flour
• Avoid cross-contamination: separate toaster, clean surfaces, and care with shared frying oil

Symptoms often improve within weeks, but the bowel lining may take months to years to heal fully.

Follow-up

Follow-up includes a repeat antibody blood test (which should fall over 6 to 12 months), checks of iron, vitamin D, folate and B12, and a bone density scan if advised. Your doctor may also recommend some vaccines. Your close relatives should be offered a blood test.

Common questions

This leaflet is general information and does not replace advice from your own doctor. Version 1.0, October 2026. Next review October 2028.