What Is Intestinal Methanogen Overgrowth?

What Is Intestinal Methanogen Overgrowth?

What Is Intestinal Methanogen Overgrowth?

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Key Takeaways

  • Intestinal methanogen overgrowth (IMO) is a digestive condition caused by an overabundance of a microorganism called archaea.
  • Common symptoms of IMO include constipation, bloating, and gas.
  • Treatment requires a holistic, individualized approach that may include medication, diet changes, and targeted supplements.

Intestinal methanogen overgrowth (IMO) is a condition that occurs when levels of methane-producing microbes are abnormally high in the intestines. This imbalance can lead to digestive issues and other uncomfortable symptoms.

Your gut microbiome, the collection of microorganisms that live in the gastrointestinal tract, plays a crucial role in digestive health and overall well-being. A balanced microbiome contains the right mix of these microorganisms in healthy ratios. When the balance is disrupted, it can lead to digestive and metabolic issues. 

In the case of IMO, the disruption is caused by an overabundance of archaea, a microorganism that produces methane. This blog article will explore what IMO is, what causes it, and what to expect with diagnosis and treatment.

Nourish offers personalized nutrition counseling and accepts the most popular insurance carriers so you can heal your gut. Get started with a dietitian today.

What Is Intestinal Methanogen Overgrowth (IMO)?

Intestinal methanogen overgrowth (IMO) is the updated name for a type of overgrowth in the small intestine. Previously called methane-dominant small intestinal bacterial overgrowth (SIBO), experts have suggested IMO is a more appropriate name because archaea aren’t actually bacteria at all (although you may still see clinicians who refer to it as methane-dominant).

SIBO refers to an overgrowth of bacteria in the small intestine. The bacteria release gas when they ferment carbohydrates that can cause digestive symptoms, and the type of gas determines what kind of SIBO someone has. 

Until recently, the two primary categories were hydrogen-dominant (bacteria that release hydrogen) and methane-dominant (microbes that release methane). 

Who is at Risk for IMO?

IMO can affect anyone, but certain factors may increase the risk, including:

  • History of food poisoning that compromises gut motility (how quickly food moves through the intestines) or inflammation.
  • Surgeries or other medical issues like inflammatory bowel disease (IBD) affect the normal anatomy of the gut.
  • Specific medications like antibiotics and acid-blocking drugs that disrupt the normal flora of the gut microbiome.

Why is IMO a Problem?

Bacteria and archaea are a normal part of the gut, but when these microbes are found in numbers that are higher than expected, they also produce higher amounts of gas.

IMO can cause significant discomfort that interrupts daily life and, when untreated or severe, can interfere with nutrient absorption.

Symptoms of Intestinal Methanogen Overgrowth

The primary IMO symptoms occur in the digestive tract, but fatigue or poor concentration are also common. Since methanogen overgrowth can look like other health conditions, it may take time to get a proper diagnosis. For example, it’s estimated that up to 78% of people with IBS actually have SIBO or IMO.

Common gut symptoms from methanogen overgrowth include:

  • Constipation.
  • Bloating.
  • Gas.
  • Abdominal pain.
  • Nausea.
  • Heartburn.

These symptoms can be related to slow motility and high methane levels in the gut. 

How to Diagnose IMO

Breath tests are the current diagnostic tool for SIBO and IMO. They aren’t perfect, and studies suggest false positives or negatives are possible, but they are the gold standard for now.

Breath tests are non-invasive and only take a small amount of preparation. Typically the test requires following a specific diet protocol and avoiding certain foods and supplements that may interfere with interpretation (your healthcare practitioner can provide detailed instructions.

On the test day, a lactulose or glucose solution is consumed, and breath is measured at regular intervals to look for higher than expected values of hydrogen, methane (or both). If more methane is produced than expected— levels over 10 ppm at any point during —it indicates IMO.

Some diagnostic companies may offer at-home SIBO testing without requiring a practitioner order. These aren’t recommended because interpretation takes a trained eye.

Treating Intestinal Methanogen Overgrowth

Intestinal methanogen overgrowth treatment is complex, making it essential to work with a provider specializing in SIBO or IMO. In many cases, it may take a combination of trial and error to find what works for you.

Further, treatment goes beyond a single dose of medication. If you have IMO and take medications without addressing why you have an overgrowth in the first place, recurrence is likely.

A combination of the following treatment options may be considered for people with IMO:

  • Antibiotics. The gold standard medical treatment for IMO is a combination of two types of antibiotics: neomycin and rifaxamin for two weeks. Neomycin is a broad-spectrum antibiotic that affects all areas of the body, while rifaxamin stays within the gut. Studies show that combining these two drugs effectively lowers methane gas compared to either alone.
  • Anti-microbials. Anti-microbial herbs are a promising treatment for IMO and SIBO. Herbs like oregano oil, berberine, neem leaf extract, garlic extract (allicin), and others may help reduce archaea in the gut. Some research suggests that herbal antimicrobials could be an alternative to antibiotics (and just as effective). The decision to use herbs should be made in consultation with your healthcare provider.
  • Pro-kinetics. Pro-kinetics are drugs or supplements that help speed up digestion. They can help improve constipation and slow motility associated with IMO. Certain herbs like peppermint and ginger or nutrients like magnesium or vitamin C act like pro-kinetics and may be added in addition to other interventions
  • Nutrition. Foods to address inflammation and constipation are essential when treating IMO. If SIBO and IMO are suspected, a low FODMAP diet may be recommended to help with symptom relief. The low FODMAP diet removes short-chain carbohydrates that are rapidly fermented in the gut, but there are also other diet options depending on your specific needs. A personalized approach is key for diet support, as staying on a strict elimination too long can do more harm than good. For severe cases or relapse, a liquid elemental diet may be considered. An elemental diet provides all the necessary nutrients already broken down into easy-to-digest forms. It should be overseen by a doctor or dietitian who can ensure you get all the calories and nutrients you need. A registered dietitian specializing in digestive health can work with your doctor or care team to support your healing journey. If you need personalized nutrition guidance for IMO, consider booking a virtual appointment with a Registered Dietitian.
  • Meal timing. The timing of meals also matters for IMO. You have two primary types of digestive waves: peristalsis and the migrating motor complex (MMC). Peristalsis helps you digest and push food down the digestive tract. The MMC turns on when you’re fasting between meals to ensure everything is cleared out. People with IMO may need to space meals farther apart or avoid grazing and snacking throughout the day to help turn on the MMC to clean out bacteria and support healthy bowel movements.
  • Supplements. Certain supplements may also be a part of your nutrition plan, including nutrients you may be missing due to malabsorption, certain strains of probiotics to support healthy bacteria, or botanicals that address gut inflammation. These should be personalized to your needs and recommended by your care team.


Intestinal methanogen overgrowth is a complex condition resulting from an imbalance of archaea in the gut. Several factors put someone at risk for IMO, including medications, certain health conditions, and food poisoning. 

Treatment methods for IMO require a multi-faceted approach that may include antibiotics, supplements, and nutrition to support healing. Your healthcare practitioner should work with you to develop an individualized plan to address your specific needs. 

Working with a Dietitian to Heal SIBO

Working with a nutrition professional is essential for symptom management and preventing relapse in the future.

A gut health nutritionist can help you ensure you are getting the nutrients you need while adjusting your diet to support symptoms and healing. They can also help you sort through the misinformation and choose the appropriate supplements for your needs. Nourish offers personalized nutrition counseling and accepts the most popular insurance carriers. Get started with a dietitian today.

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