Almost everyone feels bloated from time to time — after a large meal, a fizzy drink or a rich weekend. But when a tight, swollen or gassy tummy becomes a regular part of your week, it is reasonable to ask what is driving it. Bloating is rarely caused by one thing, and while it is usually harmless, a few well-chosen blood tests can help rule out treatable conditions and point you in the right direction.
Common causes of persistent bloating
Most ongoing bloating comes down to how your gut handles food, gas and movement. Frequent contributors include:
- Irritable bowel syndrome (IBS) — a very common functional cause, often linked to certain foods and stress.
- Coeliac disease — an immune reaction to gluten that can cause bloating, wind and altered bowel habits.
- Food intolerances — such as difficulty digesting lactose or certain fermentable carbohydrates.
- Helicobacter pylori infection — a stomach bacterium that can cause indigestion and bloating.
- Constipation and gut motility — a sluggish bowel traps gas and causes distension.
- Hormonal changes — many women notice cyclical bloating around their period.
Which blood tests can help
Blood tests cannot see bloating directly, but they can check for the underlying conditions that produce it. A sensible first-line set often includes a coeliac antibody screen, a test for H. pylori, thyroid function (an underactive thyroid slows the gut), a full blood count to look for anaemia, and inflammation markers such as CRP or ESR. Together these help separate a functional problem like IBS from something that needs specific treatment.
The gluten point that catches people out
If you are considering a coeliac test, one detail matters enormously: you must be eating a gluten-containing diet at the time. The coeliac antibody test relies on your immune system reacting to gluten, so if you have already cut it out, the result can be falsely negative. Keep eating normal amounts of gluten — roughly the equivalent of a few slices of bread a day — for several weeks before testing, and speak to a clinician before making dietary changes.
Investigate bloating
Coeliac antibody and H. pylori testing check two of the most common treatable causes of persistent bloating — a practical first step before wider investigation.
Book bloating bloodsWhen to see a doctor promptly
Most bloating is benign, but some symptoms should never be ignored. See a doctor without delay if bloating comes with unexplained weight loss, rectal bleeding or blood in your stool, difficulty swallowing, persistent vomiting, a new and lasting change in bowel habit, or if you are a woman with persistent bloating that does not settle — this last pattern always warrants assessment. These red flags need proper medical evaluation rather than self-management.
Putting it together
For most people, bloating improves with a combination of dietary tweaks, regular meals, managing stress and staying active — once serious causes have been excluded. Blood tests give you the confidence to make those changes knowing you are not missing something important.
Investigate bloating
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Specialist interest: Cardiovascular Medicine · OneMedicine, CQC-registered clinic