Bad breath, also called halitosis, is a common problem. Foods such as garlic, onions, or fish often cause it. Halitosis can also be related to a problem with the teeth, gums, or tongue that a change in hygiene could help.

Other causes of bad breath can involve the esophagus, stomach, or intestines, requiring medical treatment to resolve.

1. Improve Digestion and Gut Health

A healthy eating plan is important for overall health and may help prevent bad breath. Eating processed foods (like those with added sugars) can disrupt the friendly microbes that populate the mouth and digestive system, leading to tooth decay, less effective digestion, and bad breath.

Working with a healthcare professional, such as a registered dietitian, can help you adopt an eating plan that supports gut health and manages or prevents halitosis.

2. Treat Acid Reflux and GERD

Occasional acid reflux or its chronic counterpart, gastroesophageal reflux disease (GERD), can cause bad breath. Acid reflux occurs when the stomach’s contents, including stomach acid, bile, and undigested food, move back up the esophagus (food tube) and into the mouth. Reflux leads to symptoms of heartburn, bad breath, and a sour taste in the mouth.

You can treat occasional heartburn with over-the-counter (OTC) antacids. When acid reflux occurs more than twice a week, a healthcare provider may diagnose GERD and prescribe a proton pump inhibitor (PPI) drug.

Changing your lifestyle may also help. You may want to avoid food and drinks that trigger acid reflux. These vary by individual, but some common ones are:

• Acidic foods and beverages
• Caffeine
• Carbonated beverages
• Chocolate
• Mint
• Spicy foods

Not eating before lying down, quitting smoking, and managing weight are also helpful in avoiding acid reflux and GERD.

3. Avoid Trigger Foods 

Certain foods can also cause bad breath. Most people learn which foods cause bad breath by eating them and sensing the results. The foods that cause halitosis will be different from person to person.

Some of the more common foods that causing bad breath include:

• Alcoholic beverages
• Coffee
• Cruciferous vegetables, including broccoli, cauliflower, cabbage, and kale
• Dairy products
• Fish
• Garlic
• Onions
• Pickled foods
• Spicy foods
• Tuna fish

4. Maintain Good Oral Hygiene Practices

Keeping up with good oral hygiene also helps manage bad breath. This means:

It’s commonly suggested that people get their teeth cleaned every six months or so. People with certain conditions affecting the mouth or digestive system might need to get their teeth cleaned more often.

5. Make Lifestyle Changes

People who notice they frequently have bad breath may want to consider changing their everyday habits. What is causing the bad breath may not be obvious, so some trial and error may help them track it down.

In addition to avoiding trigger foods and being consistent with oral hygiene, things to try include:

• Using mouthwash that contains mint to mask the smell
• Cutting back or avoiding alcoholic beverages altogether
• Drinking enough water every day to prevent dry mouth (a cause of bad breath)
• Stopping smoking

6. Kill Harmful Bacteria (H. Pylori and Gut Issues)

The gut microbiome refers to all the helpful and harmful bacteria living within the digestive system. Sometimes, the “bad” bacteria can start to grow out of control. One such bacterium is Helicobacter pylori (H. pylori).

An infection of H. pylori can cause many digestive problems, including ulcers in the stomach and bad breath. Antibiotics are used to reduce the amount of H. pylori in the stomach. After treatment, the halitosis improves.

7. Address Gum Disease

Gum disease is common and can cause bad breath. It may not cause symptoms, such as pain, that prompt immediate treatment. However, gum disease, such as periodontitis, could worsen without treatment.

The buildup of bacteria in the mouth forms plaque, which starts a cascade effect leading to gum disease and bad breath. Regularly seeing a healthcare provider, such as a dentist or dental hygienist, can help detect and treat gum disease.

8. Manage IBD

Inflammatory bowel diseases (Crohn’s disease, ulcerative colitis, and indeterminate colitis) can also cause bad breath. Both genetics and environmental triggers can lead to these autoimmune diseases that produce inflammation in the digestive system.

People with IBD, especially ulcerative colitis, have higher rates of bad breath than people who don’t live with these diseases.

Treating IBD involves managing the inflammation it causes in the digestive system. Treatment can include medications, lifestyle changes, and adjunct (additional) therapies. If there’s less inflammation causing problems in the mouth and digestive organs, bad breath may be reduced.

9. Manage Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a digestive condition that can cause several symptoms, including pain, cramping, constipation, and/or diarrhea. It is challenging to diagnose and treat.

Some people with IBS report bad breath. There’s no clear reason why the two are connected, except that problems with digestion may lead to halitosis. Bad breath is not a classic sign of IBS, but people with IBS have reported it.

10. Natural Remedies for Stomach-Related Bad Breath

Home remedies for bad breath may not address the underlying cause but could provide some relief. They include:

• Chewing herbs such as basil, parsley, and mint, which releases their essential oils
• Eating apples, citrus fruits, fermented foods, probiotic foods (foods with friendly bacteria, such as yogurt) or pineapples
• Green tea, which may help inactivate bacteria connected to bad breath
• Mouthwashes of essential oils, such as tea tree, being careful not to swallow any
• Using a mouthwash containing baking soda (sodium bicarbonate)

Other Causes of Bad Breath From the Stomach

Other medical conditions that could lead to bad breath include:

• Achalasia (a swallowing disorder)
• Colon cancer
• Esophageal diverticula (pouches in the lining of the esophagus, or food tube)
• Gastric cancers (such as esophageal cancer)
• Liver disease
• Pyloric stenosis (a narrowing between the stomach and the first part of the small intestine)

When to See a Provider About Persistent Bad Breath

Bad breath that is particularly foul, lasts a long time, and does not respond to lifestyle changes should be diagnosed by a healthcare provider.

Most people find it helpful to first see a dentist or dental hygienist to address bad breath. If the problem is caused by gum disease or an overgrowth of bacteria, a cleaning or other treatments may help.

If the mouth is not the problem, a visit to a primary care provider, internal medicine specialist, and/or a gastroenterologist. There are reasons for bad breath that don’t involve the digestive system, but H. pylori infection and GERD are two of the most common causes. A gastroenterologist or, in some cases, an internal medicine specialist can treat these conditions.

Summary

Bad breath, or halitosis, is common. It may be possible to pinpoint foods that cause bad breath, and avoiding those may help. There could also be more systemic reasons for bad breath that may require treatment from a healthcare provider.

Some of these causes involve the mouth, directly or indirectly, and a dental professional may help. Others are related to more persistent or serious digestive diseases, for which working with an internal medicine specialist or a digestive specialist (gastroenterologist) may be necessary.