Bad Breath from Stomach Bacteria or Poor Oral Hygiene: Understanding the Causes of Halitosis

Nearly 50% of the human population is said to experience bad breath or halitosis at some point in their lives. It can be an embarrassing condition and can even cause mental distress and persistent anxiety in people. Though some of the most common causes of bad breath are poor oral hygiene and eating foods with pungent odors, other conditions are also known to cause halitosis. Bad breath from stomach and intestinal conditions are also recorded. Conversely, conditions such as morning breath can be fixed by altering lifestyle habits or diagnosing the underlying cause. 

In most cases, maintaining strict oral hygiene recommended by your dentist can help you battle morning breath and other forms of halitosis. However, when the problem fails to reduce despite consistent efforts in maintaining oral hygiene, the issue hints at an underlying disease for your family doctor to diagnose. Whether it’s bad breath from stomach bacteria, reflux, or salivary gland issues, a complete examination will be required to understand the cause of the problem. Read on to know more about foul breath, how to prevent morning breath, and the causes of this distressing condition. 

types of bad breath smells

What Causes Bad Breath?

Understanding the causes of halitosis is essential to prevent bad breath from the stomach, oral cavity, or any other possible sources of the problem. 

  • Poor Oral Hygiene

    • Every day, a thin coating of salivary proteins, remnants of food, and bacterial colonies cover the teeth - called plaque. 
    • Regular removal of plaque is essential for both oral hygiene and to prevent bad breath.
    • Plaque can cause gum disease or periodontitis, a condition that can cause pockets and the collection of debris and plaque. This can lead to bad breath. 
    • Not brushing your tongue, and cleaning your dentures or orthodontic retainers can also produce odors and foul breath. 
    • Proper oral hygiene ensures there are no decaying food particles in the mouth, and also removes plaque and the build-up of coating over the tongue. 
  • Food 

    • Food can get stuck between your teeth and in some of the hard-to-reach parts of your mouth. 
    • The chemical breakdown of food in the mouth by both bodily factors and bacterial effects can result in a foul odor. This can cause bad & morning breath. 
    • Several foods have pungent odors that can cause bad breath as well. The pungent oils and chemicals in food pass into the intestines and are absorbed into the bloodstream, from where they travel to the lungs and are released into the exhaled air causing bad breath. 
    • So, what foods cause bad breath? Here’s a short list: 
      • Coffee
      • Onion
      • Garlic 
      • Spices
      • Alcohol 
      • Certain varieties of cheese
      • Soda 
  • Smoking, Chewing Tobacco & Cancer

    • While both smoked and smokeless tobacco have their odors, these habits result in increased susceptibility to poor oral hygiene, gum disease, and other oral diseases that can cause bad breath. 
    • Tobacco consumption can also lead to oral and throat cancer. Oral cancers often lead to an infection of the mouth which can present as bad breath, in case you were wondering if bad breath is a sign of cancer. 

breath smells like mothballs

  • Infections 

    • You might have noticed when you have a sore throat that bad breath is often a noticeable symptom. 
    • Oral, throat, and ear infections can all produce bad breath. 
    • Dental-origin infections such as tooth abscesses caused by decay, gum infections, surgical wound infections, and improper healing after a tooth removal can all result in bad breath. 
    • Similarly, tonsillitis and tonsil stones too can cause bad breath in people. 
    • Middle ear infections are also known to present with foul odors. 
    • Apart from these infections, upper respiratory tract infections are also causes of bad breath.
  • Medications

    • Certain medications and their side effects can present as bad breath in individuals. 
    • Either the active component in the medication or the byproducts after a bodily breakdown can travel to the lungs and eventually exit the body through the breath leading to foul-smelling breath.
    • Certain drugs also cause dry mouth - an important factor causing bad breath. 
  •  Gastrointestinal diseases

    • Since the mouth is a part of the digestive system’s alimentary canal, issues with the stomach and the intestines can lead to bad breath. 
    • Bad breath from stomach infections and intestinal diseases are a common occurrence. 
    • Stomach ulcers caused by bacteria have been known to have bad breath as a symptom.
    • Diseases like gastroesophageal reflux disease or GERD are also known to be some of the primary causes of bad breath. 
    • Bad breath from stomach bacteria is often a result of illnesses such as gastritis and other inflammatory conditions of the stomach and intestines. 
  • Salivary gland illnesses

    • Salivary gland stones or sialoliths can cause blockages in the duct of the salivary glands, leading to reduced salivary flow and hence a dry mouth. 
    • Saliva keeps the mouth moist and flushes debris and bacteria from the oral cavity. So, does dry mouth cause bad breath? In the absence of saliva, bacterial buildup and food decay are faster which makes conditions more conducive to odor and bad breath. 
    • Severe autoimmune diseases such as Sjogren’s syndrome cause dry mouth or xerostomia, which is characterized by halitosis. 
  • Sexually Transmitted Diseases

    • Several STDs affect the oral cavity and cause infections in it. 
    • Syphilis, gonorrhea, and chlamydia can make one’s breath smell bad. 
    • Bad breath due to STDs is an important symptom in diagnosing some of these diseases. 
  • Other Causes

    • There also exist several other systemic causes of bad breath. In case you’ve been wondering “why does my breath smell bad even after brushing?”, it might be time to make a dentist’s appointment as this is often a sign of an underlying condition. 
    • Fishy breath and malodor are often a result of kidney disease - a serious condition. 
    • Bad breath can also be a sign of undiagnosed diabetes in individuals. 
    • Diseases of the metabolism and hormonal mechanisms of the body can also result in bad breath. 
    • Sinus infections and sinusitis can cause bad breath as several sinuses have openings in the mouth. 

Understanding Halitosis: Types of Bad Breath Smells & Odors

Certain causes of halitosis can lead to very specific smells that can tell you about the nature of the condition, some of the types of bad breath smells and their meanings are as follows:

  • Fruity breath/Fruity morning breath: Caused by diabetes
  • Fishy breath: Kidney disease 
  • Mothball breath: Sinusitis or gum disease
  • Rotten egg breath: GERD 
  • Moldy breath: Sinus infections and candidiasis 
  • Fecal breath: Bowel obstruction or sexually transmitted diseases

Diagnosis & How to Know if You Have Bad Breath

  • Knowing if you have bad breath can often be a complicated affair as it is tough to objectively judge your breath odor. Asking friends and family is not entirely reliable either. 
  • A lot of people that do not have halitosis often experience anxiety over the fear of having bad breath or morning breath, whereas those that usually have it are unaware of the problem. 
  • Visiting the dentist regularly helps as they’re trained to check for these issues. 
  • The dentist will undertake a comprehensive examination of your mouth, tongue, and throat. They might even smell your breath to make a complete diagnosis. 
  • Modern tools like halimeters are designed to measure volatile sulfur compounds - chemicals known to cause bad breath. High concentrations of these chemicals are determined by this device and aid dentists in diagnosing halitosis and morning breath. 
  • Your dentist will ask you questions about your dental, medical, and family history. They will also ask about your oral hygiene regimen and practices. 
  • If the cause seems to be originating from your mouth and teeth, the dentist will suggest procedures and the right method to brush your teeth so you know how to prevent morning breath. 
  • However, if the problem seems to be systemic, your dentist might refer you to your family physician for further examination of the problem. 

How to Prevent Morning Breath & Other Forms of Halitosis

Here are some easy methods by which you can prevent morning breath and halitosis: 

  • Get regular dental check-ups. A complete oral examination every six months is essential. Your dentist will check for any anomalies and will also give you a teeth cleaning, helping you get rid of stubborn plaque and tartar deposits. 
  • Brush your teeth twice a day. Use a trustworthy fluoride toothpaste and floss regularly to relieve the trapped particles of food between your teeth. Don’t forget to brush your tongue and keep it clean from the build-up of deposits. You can also use an antibacterial mouthwash to keep your breath smelling fresh for a few hours. Replace your toothbrush every 3 months, and in case you wear dentures, brush and sanitize them every night. Do not go to bed while wearing your dentures.
  • Keep yourself hydrated by drinking a lot of water. In case you have xerostomia or dry mouth, use a saliva substitute suggested by your dentist or doctor. 
  • If you smoke or chew tobacco, try to quit the habit. Get in touch with help in case you’re finding it difficult to quit the habit. 
  • Cut down on your alcohol and caffeine intake to promote better breath. 
  • Eat fresh food like fruits and vegetables 
  • Brush at night without fail to prevent morning breath. 
  • Keep a tab of the foods you eat and chew on sugar-free gum to make sure you have regular salivary flow and fresh smelling breath.


  • Treating bad breath often involves addressing the cause. 
  • If your dentist identifies gum disease, dental decay, or any other oral infections, they might address and treat these causes. 
  • Deep cleaning is often done to treat gum disease, and your dentist will put you on an antibiotic regimen to clear oral infections. Fillings and root canal treatments address decayed teeth. 
  • If your dentist thinks it’s a systemic issue, they might refer you to your family physician that might run a number of tests before they diagnose the true cause of bad breath. 

bad breath from stomach

While bad breath might be indicative of an oral problem, it is not to be taken lightly, as it can also manifest as a symptom of a number of underlying diseases. Get in touch with your dentist or your physician to address your issues with bad breath at the earliest.