Bad Breath From Gut: What Issue Could I Have?

Bad breath is a common occurrence for all of us. You may notice that your breath smells particularly bad after eating certain foods or waking up in the morning. While this is a completely normal symptom, there may be an underlying issue if you notice that your breath consistently produces a foul odour. 

Persistent bad breath is typically associated with chronic halitosis, a dental term that describes poor oral hygiene which causes bacteria build-up and gum disease. However, your bad breath could also indicate poor gut health and even a gastrointestinal disorder or condition. 

This page will break down several gut disorders that cause bad breath and provide related symptoms to help identify the reason behind your foul smell. 

What Does Gut Breath Smell Like?

Patients with gut problems have described multiple noticeable smells from the mouth. These include a:

  • Rotten smell that resembles the scent of rotten eggs or sulphur. This is the most common smell people describe when experiencing chronic bad breath due to a gastrointestinal disorder.
  • Sweet/fruity smell that is like acetone, it is typically found in people with diabetes. 
  • Fungal smell that is comparable to mould, this scent is related to bacterial growth and infection. 
  • Poop smell which is a noticeably foul odour and indicates bowel issues such as constipation.
  • Fish smell that closely resembles urine or seafood, it is common in people suffering from kidney disease. 

The first step to determining the underlying cause behind your foul breath is identifying the particular smell. This will help narrow your research into the specific gastrointestinal region that may be causing the issue.

What Causes Bad Breath From the Stomach?

There are various gastrointestinal conditions that could be triggering your foul-smelling breath, ranging from minor issues to more severe health problems. 

Gut problems that cause bad breath include:

  • Bowel obstruction
  • Gastroesophageal reflux disease (GORD)
  • Irritable bowel syndrome (IBS)
  • Kidney disease
  • Excessive gut bacteria
  • Infection in the digestive tract
  • Helicobacter pylori infection
  • Liver disease
  • Gallbladder issues

The following section will define these conditions, noting what kind of smell they produce, how they make the smell and other related symptoms. 

Before you determine the specific gut issue you have, it is important to note any other symptoms you may be experiencing. Ultimately, this will help you draw a better conclusion and guide your decision to seek medical assistance.

Gut breath potential causes (conditions and diseases).

Bowel Obstruction

A bowel obstruction is when your small or large intestine is blocked, causing severe constipation and bloating. 

The blockage traps fermented foods and waste in your intestinal tract. Consequently, the odour emitted from these materials travel upwards to your mouth and cause your breath to smell like faeces.  

Other signs and symptoms of a bowel obstruction include:

  • Severe abdominal pain and cramping 
  • Bloating and swelling of the abdomen
  • Constipation 
  • Nausea
  • Vomiting 
  • Irregular or absent bowel movement
  • Unable to pass wind 

An intestinal obstruction is a serious condition that requires immediate medical attention and possibly surgery to relieve pressure. Obstructions can cause infection and tissue death in the small or large intestine if left untreated.

Gastroesophageal Reflux Disease (GORD)

GORD, sometimes referred to as GERD, is the medical term used to describe chronic acid reflux (heartburn).

GORD occurs when a mixture of stomach acid, bile and undigested food rises into your oesophagus. As a result, this combination entering your oesophageal canal can cause a faecal smelling breath.

Aside from bad breath, other symptoms of GORD are:

  • Regular heartburn (more than twice a week)
  • Consistent belching (burping)
  • Sore throat
  • Oral health problems such as gum inflammation or tooth enamel deterioration
  • Problems with swallowing or drinking
  • Dysphagia (sensation of a lump in your throat)
  • Regurgitating excess acid that is sour tasting

If you believe that GORD is causing your bad breath, consider consulting a gastroenterologist for treatment. 

GORD is often treated with a simple lifestyle and diet change, alongside medications such as a proton pump inhibitor to help reduce your stomach acid. In extreme cases of GORD, your doctor may recommend laparoscopic surgery to help tighten the valve between your stomach and oesophagus. 

For more information on treatment options, visit our service page here.

Irritable Bowel Syndrome (IBS)

IBS is a common chronic gut disorder located in your large intestine. This gastrointestinal disorder varies from patient to patient, causing loose bowel movements in some and constipation in others. 

As a result, those experiencing frequent bowel movements will likely suffer from poor digestion and malabsorption, leading to a rotten smelling breath.

Meanwhile, IBS patients with constipation will notice a faecal smell in their mouth due to their inability to pass stool. 

Aside from your breath and altered bowel movements, other symptoms of IBS include:

  • Abdominal pain, cramping and bloating
  • Presence of mucus in your stool
  • Bowel still feeling full after going to the bathroom 
  • Nausea

Reducing stress and diet changes are popular ways to help reduce the frequency of your bad breath. As IBS is a chronic disease, treatment focuses on management rather than a single cure.

Medical associations and researchers have noted that IBS does not cause any long term damage to the gastrointestinal tract. For further information, head to our IBS management page to find out how you can live with your gastrointestinal disorder.

Excessive Gut Bacteria

Your gut microbiome is home to trillions of different types of bacteria. While this may seem like an unsettling thought, a healthy microbiome actually aids the efficiency of a healthy gut. However, the small intestine is less effective in hosting gut bacteria and can cause many issues.

Excessive bacteria in the small intestine can cause extreme amounts of rotten-smelling gas and belching, causing your breath to have an unpleasant smell. This condition is referred to as small intestinal bacterial overgrowth (SIBO).

Other symptoms of SIBO include:

  • Loss of weight and appetite 
  • Abdominal pain, cramping and bloating
  • Malnutrition 
  • Diarrhoea
  • Constipation 
  • Excessive fatigue

SIBO is most common in people with IBS or other intolerances such as lactose or fructose.

To resolve bad breath caused by SIBO, you will need to see a gastroenterologist. Most commonly, a doctor will prescribe you probiotics and recommend lifestyle changes to eliminate the bad bacteria from your gut.

Infection in the Digestive Tract

An infection in your digestive system is another potential cause of your bad breath. Most of these diseases come from infected water or food particles that attack our gut.

The most common type of infection in the digestive tract is giardiasis, which creates a foul-smelling belch that can cause bad breath. 

Alongside this, other symptoms of giardiasis include:

  • Watery or greasy stools 
  • Stomach issues such as cramping or bloating 
  • Constantly passing wind

Typically, most gut infections go away after two to three weeks. However, if you find yourself with severe symptoms alongside bad breath, you may need a course of antibiotics. 

Helicobacter Pylori

Helicobacter Pylori is another type of healthy bacteria located within your gut. However, when an excessive overgrowth of h pylori occurs in the gut, it can cause various stomach problems. This condition is most common when you contact infected food, drink or people. 

H pylori infections are known for producing a rotten smelling breath, with peer-reviewed studies noting high sulphide levels in infected patients’ breath tests.

Other certain symptoms of this gut infection include:

  • Pain and bloating around the upper abdomen 
  • Black stool
  • Peptic stomach ulcers 
  • Nausea 
  • Vomiting 
  • Belching

Most infections require a set of antibiotics to help expel the excessive bacteria. To limit the amount of excess acid produced by the body, a doctor may also prescribe proton pump inhibitors. These will help reduce the intensity and frequency of the foul odour coming from your mouth.

Liver Disease

Bad breath is another common indicator of liver disease, as it can cause a build-up of waste and toxins within your body. 

When your liver starts to fail, it can no longer effectively process waste products like the kidney. Consequently, this causes a range of health implications alongside a fishy or faecal smelling breath.

Other liver disease signs and symptoms to keep an eye on include:

  • Yellowing of the skin (jaundice)
  • Excessive fatigue 
  • Diarrhoea 
  • Bruising or bleeding easily 
  • Itchy skin

Liver disease is a serious medical condition that will need to be treated as fast as possible. Failure to manage the disease can result in liver failure, which has extensive and severe health implications. Check out our liver disease management service to understand your treatment options.

Gallbladder Issues

Your gallbladder’s role is to produce bile and other digestive juices. However, when the bile ducts are blocked, it can cause a foul-smelling belch that causes your breath to smell similar to rotten eggs. 

Other symptoms that may indicate issues with your gallbladder include:

  • Sharp abdominal pains on the upper right-hand side
  • Fever 
  • Nausea 
  • Vomiting 
  • White or pale stools 
  • White or pale tongue 
  • Skin rash
  • Discolouration of the skin underneath the eyes

If you think that you have an issue with your gallbladder, you should seek medical assistance as soon as possible. In some severe cases, you may require gallbladder removal to prevent further complications.

Kidney Disease

While not related directly to your gut health, chronic kidney disease is another common cause for bad breath. The kidneys’ main responsibility is to process any waste or toxins in your blood.

When your kidneys stop functioning, it decreases your body’s ability to expel waste and causes a toxin build-up. 

A common symptom of excessive toxins in the body is a fishy smell on your breath. This is known as ammonia breath. 

Assessing the symptoms of kidney disease is a difficult task, as most patients often exhibit little to no signs. However, some general symptoms include:

  • High blood pressure
  • Excessive fatigue
  • Loss of appetite and weight

If you have noticed a fishy odour on your breath, you should consider consulting a doctor for a physical examination. A healthcare professional may recommend a blood test to measure your toxin levels.

How to Stop Bad Breath From Gut

If you believe that your bad breath results from a gut condition or disorder, you should consider seeing a gastroenterologist for an examination. 

Gastroenterologists effectively help treat and manage your disorder or condition, which can minimise the frequency of your bad breath. Treatment options range from simple solutions such as probiotics in your diet to more complex surgeries. 

Check out The Centre for Gastrointestinal Health’s service page for more information on professional treatment options. Alternatively, you can contact us via phone or email with any questions that you may have concerning your bad breath. 


Bad Breath from Stomach Home Remedies 

There are some home remedies that you can use to minimise the intensity of your bad breath.

Home remedies for bad breath caused by stomach problems include:

  • Practice good oral hygiene: Ensuring that you brush your teeth twice a day with strongly scented toothpaste can help mask the odour for a short period. 
  • Use gum: Chewing flavoured gum creates excess saliva, reducing the smell’s intensity. 
  • Avoid triggers: Particularly for GORD, take note of the foods that trigger your bad breath and try to eliminate them from your diet. 
  • Stop smoking: Cigarette smoke can also cause stomach acid to enter your oesophagus, which creates a strong smell. 

While effective, it is worth noting that these are temporary solutions that only mask the odour. If you want a permanent resolution to your gut breath, you should see a gastroenterologist.