Hydrogen Sulphide breath test
Hydrogen Sulphide breath test

Hydrogen Sulphide breath test

The Functional Gut Clinic in partnership with OMED Health is delighted to announce the launch of a novel breath test to detect the presence Hydrogen Sulphide producing bacteria within the GI tract. Hydrogen Sulphide is a highly volatile gas most commonly associated with an ‘eggy’ smell and is only usually present in the gut in very low concentrations.

High gut levels of Hydrogen Sulphide (H2S) are associated with an array of gut symptoms such as diarrhoea, abdominal pain and excessive mal-odorous (eggy) flatulence. High levels of H2S have also been shown to increase gut permeability and inhibit the effectiveness of the gut’s immune system to trap and kill pathogenic bacteria. H2S levels are also higher in some patients with Inflammatory Bowel Disease (IBD) and may interfere with the beneficial effects of some short chain fatty acids.

We have recently established the normal range of H2S levels in a healthy population and found that this lies within the parts per billion (ppb) range (see graph below) requiring sophisticated analysis using Mass Spectrometry1. H2S Breath samples are taken using collection bags which are commonly used in breath analysis with proven sample stability.

This graph shows our normal range for H2S (blue) which is below 25ppb at baseline and does not rise following the Lactulose challenge. The orange line shows a positive H2S test which is typically higher at baseline and also increases following lactulose challenge. 

Because hydrogen sulphide producing bacteria often out compete other gut microbes for hydrogen gas in the gut lumen, patients with a H2S predominant profile often produce a ‘flat-line’ false negative hydrogen and methane breath test. Our new innovation will fill the gap left by current breath testing modalities and reduce the number of false negative tests for patients with unexplained gut symptoms.

We are now offering in-clinic H2S breath testing either as a stand alone or combination test (along with hydrogen and methane breath testing). If you are interested in referring a patient for a H2S breath test then please complete the online referral form for “Hydrogen Sulphide Breath Test”.

Test combinations and self pay prices:

H2S – standalone Lactulose breath test in clinic– 4 breath bags (0-min, 45-min, 90-min, 180-min) with Lactulose – £200

H2S Combo – Lactulose SIBO Hydrogen and Methane Breath Kit done in clinic for on the day test results with 4 breath bags shipped for H2S analysis (results usually within 5-days).

If you / your patient has private medical insurance the cost of the HMBT will be deducted from the combo price.

Treatments for a positive H2S test:

H2S levels can be reduced by reducing the amount of sulphurous foods in the diet such as broccoli and cabbage as well as dried fruits. Non-absorbable antibiotics such as Rifaximin can also be effective.


  1. Establishing normal values for Gastrointestinal Hydrogen Sulphide production in breath using selected-ion flow-tube mass spectrometry (SIFT-MS). Hobson et al – Abstract Digestive Disease Week, Chicago, USA May 2023.