Bloating

Struggling with bloating? Here’s what you need to know to find relief.

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What is bloating?

When you’re bloated, your stomach or abdomen can feel full and uncomfortable, or even painful.

This bloating happens when your gastrointestinal tract contains too much gas or air. Bloating can be mild, or more severe, and may present as:

– A visibly distended or swollen abdomen

– Feeling very full and uncomfortable

– Feeling of tightness in the abdomen

– Excess gas – belching and/or flatulence

– Rumbling or gurgling

There are several causes of bloating, so it’s important to diagnose the cause of your bloating and find out why it’s happening to you.

Why does bloating happen?

Prolonged periods of bloating could indicate an underlying health problem, if so you should see your GP.

Possible causes can include:

Irritable bowel syndrome (IBS diagnosis)
Ulcerative colitis, a form of inflammatory bowel disease (IBD), where the inner lining of the large bowel is inflamed and develops ulcers
Crohn’s disease, the other form of IBD, where some parts of your colon are inflamed
Too much bacteria in your small intestine (called small intestinal bacterial overgrowth, or SIBO)
Gastroesophageal reflux disease
Food intolerances, especially lactose or fructose intolerance
Producing too much gas (dysbiosis and fermentation)
Weight gain
Stress or anxiety
Delays in your food and drink moving on from your stomach (called gastroparesis)
Eating too quickly, so that you swallow too much air (called aerophagia)

Diagnosing bloating

Feeling bloated is no fun, but once you know what’s going on you can start to manage your symptoms and the underlying causes.

Testing options:

At the Functional Gut Clinic, we can run the following tests to diagnose the causes of bloating:

Gastric emptying test– which measures how quickly food leaves your stomach

Carbohydrate malabsorption breath test– which finds out if you have certain food intolerances (lactose or fructose)

Small intestinal bacterial overgrowth (SIBO) breath test– which finds out if you have an overgrowth of bacteria in your small intestine (called SIBO)

Oesophageal manometry– which measures the function of your oesophagus (food pipe)

24-hour pH impedance monitoring– which looks at whether you have any reflux

Colonic transit study-a non-invasive test which looks at how long it takes for faeces to pass through your bowl

Find out more and book your test

Learn more about bloating

Launch of a NEW Breath Test to measure intestinal Hydrogen Sulphide

Education| News

April 16, 2025•2 min read

Launch of a New Breath Test to Measure Intestinal Hydrogen Sulphide

Small intestinal bacterial overgrowth (or SIBO for short), as the name suggests, happens when too many bacteria grow in the small intestine where they would not normally be present. This overgrowth can overwhelm the small intestine, leading to difficult symptoms of bloating, abdominal pain, excessive gas, and altered bowel habits.

Breath tests can be used to detect SIBO, by measuring levels of hydrogen and methane which are gases produced by these bacteria. But there’s another type of gas that can also be produced by these bacteria – hydrogen sulphide.

Until recently, it’s been difficult to measure Hydrogen sulphide in breath tests as the gas itself is unstable, which makes it difficult to collect and measure in breath samples. This means that with standard hydrogen and methane breath tests (HMBTs), patients with excess Hydrogen sulphide can go undiagnosed.

In a healthy gut, this gas is present in low concentrations, but if the bacteria in your gut become unbalanced, the levels of Hydrogen sulphide can increase. High levels of Hydrogen sulphide in the gut has been linked with conditions such as ulcerative colitis, Crohn’s disease, and IBS, with higher levels associated with symptoms of diarrhoea, urgency, and abdominal pain, as well as excessive “eggy” smelling wind!

Our new breath test for Hydrogen sulphide works in a similar way to our standard HBMTs.

For the H2S breath test, you collect a series of breath samples across 3 hours after drinking a sugar substrate, which allows us to see how much gas is produced in your gut in response to the drink. You can perform this test at one of our clinics, in London, Cambridge, or Manchester. This new test will fill the gap left in the current breath testing services and can provide an extra option for patients with unexplained gut symptoms.

The Functional Gut Clinic

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