Hydrogen vs Methane SIBO symptoms

methane vs hydrogen SIBO symptoms SIBO treatment natural SIBO treatment Australian herbalist australian gut health specialist

While it is impossible to determine what type of SIBO you have based on symptoms alone, you can make a pretty educated guess. Today we will be covering the different symptoms that point to either methane SIBO or hydrogen SIBO. 

Small intestinal bacterial overgrowth, shortened to SIBO, is a digestive disorder in bacteria increase in number within the small intestine. In the past it was only on the diagnostic radar when a patient had gone through gastrointestinal surgery or had abnormal gut anatomy. More recent scientific evidence is starting to crop up showing that SIBO may be more of an issue in the broader population (1).


If you are interested in doing a deep dive into all things SIBO then check out The Complete Guide to Small Intestinal Bacterial Overgrowth in all it’s 10,000+ words and 60+ references!

Two Main Types of SIBO

Small intestinal bacterial overgrowth can be divided into a number of different subtypes. The most common form of SIBO is hydrogen SIBO, also known as hydrogen dominant SIBO or diarrhea SIBO. 

Then there is the less common methane SIBO, also known as methane dominant SIBO or constipation SIBO. 

Finally we have the new kid on the block. Hydrogen sulfide SIBO has been hard diagnose. Until recently we haven’t been able to breath test (a common way to screen for SIBO) for hydrogen sulfide SIBO. All of that is changing as new diagnostic testing is validated. 

Now, onto the main topic today. The symptoms of SIBO and how they relate to particular subtypes.  

General Symptoms of SIBO

SIBO symptoms can be vague and hard to pin down. Often there are underlying disease processes that have given bacteria the chance to overgrow in the small intestine. It can be hard to tease out and separate the underlying disease symptoms and the SIBO symptoms.

Let’s try. 

General symptoms include the following (2).

  1. Abdominal bloating 
  2. Nausea
  3. Abdominal distention 
  4. Malabsorption and vitamin deficiency symptoms

Clinically I have also certain symptoms after meals such as burping and flatulence. 

Image taken from: Small intestinal bacterial overgrowth a comprehensive review

Hydrogen SIBO

Hydrogen dominant SIBO, generally diagnosed by a sufficient rise in hydrogen on a SIBO breath test, is also called diarrhea prone SIBO. It should stand to reason that diarrhea is the main symptom that stands out with this particular subtype of small intestinal bacterial overgrowth. 

How might an excess production of hydrogen in the small intestine cause diarrhea?

There are four theories that have been proposed (3). 

  1. The by-products of carbohydrate fermentation create an osmotic-like effect, drawing water into the bowel and causing diarrhea. 
  2. The bacterial overgrowth and fatty acid by-products damage the mucosa that lines the intestinal wall causing diarrhea. 
  3. Damage to the mucosa creates a lactase deficiency. Lactase is the enzyme that we use to break down and digest lactose. Lactose intolerant people often suffer from diarrhea when they consume enough lactose.
  4. Bile salts, used to digest fat, are deconjugated. This leads to fat malabsorption (also known as steatorrhea) and diarrhea. Symptoms of steatorrhea include stools that float and a particular oily stool. 

However, hydrogen SIBO and diarrhea are not strongly correlated (4). 

Meaning, there isn’t strong science showing that excessive hydrogen production in the small bowel (hydrogen SIBO) causes diarrhea. 

While there doesn’t seem to be strong science explaining how patients with hydrogen dominant wind up with diarrhea, clinically most hydrogen dominant SIBO patients present with diarrhea.

Methane SIBO

Methane dominant SIBO, generally diagnosed by an elevation of methane on a SIBO breath test, is also called constipation SIBO

With methane SIBO symptoms that tend to present include

  • Constipation 
  • Straining on the toilet
  • Incomplete evacuations
  • Fresh blood after a bowel movement (probably caused by hemorrhoids or anal fissures) 
  • Abdominal distention upon rising

Hydrogen Sulfide SIBO

As hydrogen sulfide SIBO is a newly defined and diagnosable subtype, specific symptoms associated with this form of overgrowth are lacking. 

One recent paper looked found that abdominal pain and diarrhea were the two main symptoms present in patients with elevated hydrogen sulfide on a breath test (above 1.2 part per million) and no other gas – meaning that only hydrogen sulfide SIBO was present and not methane or hydrogen SIBO as well (4).

Symptoms Aren’t Enough To Diagnose SIBO

While it may be tempting to try to diagnose what type of SIBO you have based on your symptoms alone I would discourage it.

People with methane SIBO often present with constipation and people with hydrogen SIBO often present with diarrhea but it isn’t a sure thing. 

The image below, taken from a study that assessed 551 patients with SIBO positive breath test results, shows that constipation can occur in people with hydrogen SIBO and that diarrhea can occur in methane SIBO. 

Image taken from: Methane Production During Lactulose Breath Test Is Associated with Gastrointestinal Disease Presentation

So what can we make of this? 

The Importance of Testing

It is important to test to determine if you have SIBO and also what type. Symptoms aren’t enough.

Symptoms help to point to the possibility that SIBO is present. Testing helps to confirm it. 

Knowing what type of SIBO you have also helps when you are approaching treatment. As I have covered in the Methane Dominant Treatment Plan, the treatment approach and herbs used are different depending on which form of SIBO you have, hence the need for testing. 

byron herbalist todd mansfield gut health specialist

Need help with your digestion?

Hi, my name is Todd Mansfield. I am a clinical herbalist with a special interest in all things gut health.

If you are looking for digestive health support consider working with me. I see people online as well as in person from my clinic in Byron Bay.

More booking information here.

References and Resources

  1. Gastrointestinal bacterial overgrowth: pathogenesis and clinical significance
  2. Small Intestinal Bacterial Overgrowth (SIBO)
  3. Gastrointestinal bacterial overgrowth: pathogenesis and clinical significance
  4. A Novel 4-Gas Device for Breath Testing Shows Exhaled H 2 S is Associated with Diarrhea and Abdominal Pain in a Large Scale Prospective Trial 
  5. Methane Production During Lactulose Breath Test Is Associated with Gastrointestinal Disease Presentation

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  1. Hello, I have tested for hydrogen dominant SIBO. I have done two rounds of antibiotics and I have the exact same symptoms, mainly severe bloat. I have eliminated MOST dairy and gluten products, having it every now and then. What else do you suggest? Thank you.

  2. I have methane sibo and indigestion ….sugar cravings maybe insulin resistance. Which probiotic I can take also digestive enzym.

  3. I have done the breath test and the Methane levels were ok but; the Hydrogen levels were high. What is the difference in what foods/supplements that I should focus on?

  4. Do you recommend having getting tests done with a GP to confirm if you have SIBO and what type before coming to the Naturopath?

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