Halitosis-Insights from Medical Research and How Can We Prevent It?

Explore key insights from medical research on halitosis, including causes, diagnosis, and prevention strategies. Learn effective ways to combat bad breath and improve oral health

Have you ever felt that whenever you talk to someone, they just seem disgusted or keep avoiding you? Well, such expressions can subtly hint that you have bad breath. But don’t worry! You aren’t the only one in this situation, as it has been found that about 25% of people worldwide have bad breath all the time!

Another exciting fact about bad breath is that Americans spend $1 billion a year on breath fresheners. Such a statement is, for sure, justified, given that 70% of men and 59% of women said in a survey that they wouldn’t date someone with bad breath. Because of this, if you want to get rid of bad breath, you need to find and understand what causes it. The following article will discuss what causes bad breath and how to avoid it.

What is Halitosis?

The word halitosis is scientifically used for bad breath. The main sign of bad breath is a foul or unpleasant odor coming from the mouth. It can be a sign of many different health problems. To put it another way, it’s like your body is sending you a message to be careful.

Types of Halitosisjcm 09 02484 g001

Knowing the different kinds of bad breath is important to determine what causes halitosis and the best ways to treat it.
One might have halitosis for physiological or pathological reasons. There are two subtypes of pathological halitosis: intra-oral and extra-oral. Let’s get deeper into it,

  • Physiological Halitosis: It is the most common type of halitosis, which is the most common as well. Morning breath or eating food with strong smells like garlic, onions, or specific spices are two common causes of this form of halitosis.
  • Pathological Halitosis: This kind of halitosis is associated with an underlying health problem of medical origin. It is further divided into inta and extraoral halitosis.
  • Transient or Temporary Halitosis: When things like smoking, drinking, dry mouth, stress, or food induce temporary bad breath, it’s called transient halitosis. It goes away with lifestyle modifications.
  • Chronic Halitosis: Chronic or long-term halitosis is usually associated with systemic conditions. Healthcare professionals should examine it to rule it out as the leading cause.
  • Pseudohalitosis or halitophobia: Sometimes, people worry that they have bad breath, even if there is no scientific or societal proof to back their claim. A condition that describes this is called pseudohalitosis. A fear of bad breath, or halitophobia, may be present if the worry does not go away after expert evaluation and reassurance. The prevalence of halitophobia may reach 1% of the population.

Causes of Halitosis

The first thing that needs to be done to treat halitosis is to find its cause.

A large majority of cases (80% to 90%) of halitosis originate in the mouth.

Intra-oral Causes

The breakdown of food particles, dead cells, and saliva by bacteria is the leading cause of intra-oral halitosis. The main culprit behind the unpleasant smell is the emission of volatile sulfur compounds (VSCs) during this process. Among the most prevalent reasons falling into this group are,

  • Poor Oral Hygiene: Bad breath can result from food particles decaying in the mouth. Bacterial development occurs on the teeth, gums, and tongue when routine brushing and flossing are neglected.
  • Bacteria in the mouth: Some bacteria that live on the back of the tongue can react with amino acids in food to make sulfur compounds that smell bad.
  • Dry mouth (Xerostomia): We all know that saliva is necessary for oral hygiene, and in the condition of dry mouth, dry mouth is when the mouth doesn’t make enough saliva. It means the germs are not rinsed away less regularly, and their foul-smelling products pile up. Certain medications can also cause it as a side effect, leading to such halitosis.
  • Gum Problems (Periodontal Disease): Plaque accumulation on teeth is the culprit here. The gums get inflamed because bacteria produce toxins. The gums and jawbone are both vulnerable to the destructive effects of untreated gum disease.
  • Oral Infections: Bad breath can be a symptom of an oral infection, such as a tooth abscess, a surgical incision, or an infection of the gums.
  • Ill-fitted dentures: Orthodontic appliances such as dentures, braces, and other dental equipment that don’t fit properly can lead to inadequate oral hygiene and bacterial growth.
  • Tonsil stones: While tonsil stones aren’t directly connected to the mouth, they develop when foreign material gets stuck in the tonsils and solidifies. Because germs may live in them, they can exacerbate bad breath in the same way as the other causes mentioned above.
  • Smoking:

Extra-oral Causes

Although it is less prevalent, extra-oral halitosis might be a sign of more significant health problems. It can be due to a variety of causes, such as,

Gastrointestinal Causes.

According to scientific research, halitosis (or bad breath) is an indication of gastrointestinal disorders and diseases. Such as,

  • GERD: Gastroesophageal reflux disorder (GERD) is the first of several gastrointestinal issues that can lead to bad breath. Even according to a recent study from 2022 that proved a strong association between GERD and foul breath.
  • Stomach Ulcers: A Helicobacter pylori infection or excessive NSAID use can result in a painful sore on the small intestine’s lining called a stomach ulcer. Research has proven a strong association between H. pylori infection and halitosis. H. pylori bacteria emit sulfur compounds and sulfide compounds, specifically hydrogen sulfide and methyl mercaptan, as the primary cause.
  • Prolonged Vomiting:  Vomiting consecutively for more than 24 hours can also lead to halitosis. The virus or bacteria that causes vomiting, as well as the unpleasant odor in this case, all contribute to a dry mouth.
  • IBD: Irritable bowel diseases such as Crohn’s disease and ulcerative colitis can cause inflammation in the large intestines. This inflammation can narrow the tract and make food absorption and digestion difficult. Thus, food remains in the intestines longer, which can lead to halitosis.
  • Constipation: If the digested food stays longer in the gastrointestinal tract, it can lead to bad breath, like an excrement smell.
  • SIBO: Overgrowth of bacteria in the small intestine is known as small intestine bacterial overgrowth (SIBO). Among the few signs of small intestine bacterial overgrowth (SIBO) that might aggravate bad breath are constipation, indigestion, and gas.
  • Liver diseases: Liver diseases can also lead to halitosis, as mentioned by the National Library of Medicine, which describes fetor hepaticus, an oral condition, as “the odor of a mixture of rotten eggs and garlic.” It is commonly associated with liver illnesses, including cirrhosis, liver failure, and auto-immune diseases.
  • Bowel Obstruction: A bowel obstruction occurs when the small or large intestine cannot pass digested food. When this happens, the excrement flows backward, which can cause an unpleasant odor from the breath.
  • Gallbladder problems: The gallbladder produces bile and digestive enzymes, aiding digestion. A blocked bile duct can cause breath to smell like rotten eggs.

causes of halitosis

Some other causes can cause halitosis. It includes,

Other Causes

  • Kidney Disease: Bad breath might indicate a chronic kidney disease. According to the US National Library of Medicine, the breath in this condition smells strongly of ammonia or fish.
  • Sjögren’s syndrome:  Sjogren’s syndrome is an autoimmune disease that causes bad breath, sore muscles, blurry vision, dry skin, and dry mouth. This condition increases the likelihood of halitosis, as saliva helps clean mouths and eliminate germs that cause bad breath.
  • Medications: Over 400 medications, both prescription and OTC, have the potential to reduce saliva production. These include antidepressants, allergy medicines, and many more. When used, all of these can also lead to halitosis.

Extraoral halitosis, though less common, can be indicative of more serious health issues. These include respiratory tract infections, gastrointestinal disorders, metabolic diseases, and systemic conditions such as diabetes and liver or kidney failure.


The most noticeable sign of poor breath, or halitosis, is a powerful mouth odor. The smell can be more pungent if you smoke, consume coffee, or eat garlic first thing in the morning.

This table lists the different types of smells so that you can figure out what’s causing your bad breath.

Breath Possible Causes Additional Information
Sweet/Fruity Diabetic ketoacidosis, low-carb diets, fasting Linked to ketone release
Rotten/Fetid Mouth, throat, and lung infections; poor dental health; periodontal disease Indicates serious infections or dental issues
Nail Polish Remover Low-carb diets, diabetes Caused by acetone release
Sour Gastroesophageal reflux disease (GERD) Due to stomach contents entering the esophagus
Fecal smell Intestinal blockage Accompanied by bloating, vomiting, and cramping
Ammonia/Urine Kidney damage Known as azotemia, it indicates kidney issues


Since determining your own breath odor might be challenging, it’s better to have a trusted friend or family member do it for you. If you can’t find anybody to ask, you may test the odor by licking your wrist, waiting for it to dry, and then sniffing. If this part of your wrist smells terrible, you probably have halitosis.

If you visit a dentist, they often diagnose it based on a person’s medical history and the smell of their mouth. The whole mouth is examined to see if an infection or other reason can be found. If the dentist can’t figure out what’s wrong, he or she will send you to the right expert, like a doctor.

Many advanced devices can give a more accurate reading of an odor. A few of them are mentioned here:

Preventing Bad breath

After we’ve covered the possible causes of halitosis, we can move on to the treatments. There are different ways to treat halitosis based on what is causing it.

1. Staying Hydrated

There is no rocket science in this; hydration is the key to everything. Consuming a suitable quantity of water can greatly enhance the digestive process, reduce dry mouth, improve bad breath and safeguard against dental decay and gum disease. So make sure you consume enough water every day—about six to eight 8-ounce glasses.

2. Maintain Good Oral Hygiene

If the foul breath comes from the stomach, we usually can’t do much about it, so we seek medical help in such cases.

However, if it is related to the mouth, then bad breath may be significantly reduced by practicing excellent oral hygiene.

Brushing and Flossing: According to dental studies, the best way to reduce bad breath is to brush your teeth twice daily and floss daily. By brushing, flossing, and cleaning your tongue daily, you can significantly reduce the number of bacteria in your mouth, lowering the production of volatile sulfur compounds (VSCs).

The most effective way to prevent bad breath is to clean your teeth thoroughly for two minutes, twice a day, and floss once a day.

Brush for two minutes: Another recommendation is to brush for at least two minutes. Divide your mouth into four equal halves and brush each for thirty seconds. Brush every surface of your teeth, even the ones you chew on, not just the ones you see. If you’re not timing yourself, you can fool yourself into thinking you’re brushing for longer than two minutes. Electric brushes with built-in timers are great, but if you don’t have one, you can use a kitchen timer in the bathroom or on your phone.

If your toothbrush gets frayed, replace it within three to four months or sooner if necessary. Select a toothbrush with a soft bristle head as well.

Scrape the tongue: About 85% of bad breath comes from the tongue, so use a tongue scraper every day to reduce the bad breath.

Denture Care: Even though many people care greatly for their teeth and gums, those who use dental appliances can also have bad breath. Dentures, aligners, and retainers are susceptible to the same plaque and bacterial buildup as natural teeth.

If you wear dentures or dental prostheses, try not to wear them all the time and take them out at night. The best practice is to soak them in water overnight and clean them well with a toothbrush before putting them back in. Also, clean your retainers and braces as per your dentist’s instructions.

Talk to your doctor if you use or plan to use oral deodorizing pills or sprays. Some of them only cover up the smell for a short time. Another suggestion is to visit the dentist once a year for an examination of your dentures and any necessary changes in case they don’t fit properly.

3. Regular Dental Check-ups

To reduce the incidence of bad breath, one should visit their dentist every six months to rule out any dental issues. Gum disease, diseases, and dry mouth can all be found during regular check-ups. Professional cleaning can also remove tartar and plaque that contribute to bad breath. If the dentist can’t determine why you have bad breath, they may send you to your primary care doctor for more tests.

4. Risning Mouth With Herbal Mixture

Research indicates that a mouthwash made with tea tree oil, cloves, and basil might enhance dental hygiene, leading to a decrease in bad breath. The research used both commercial and herbal mouthwashes. It was found that plaque and gingivitis decreased dramatically with either rinse. However, unlike the commercial rinse, the herbal rinse also greatly reduces oral bacteria.

5. Keep The Mouth Moist With Chewing

It is very well known that saliva may wash away the germs and food particles that cause bad breath, so the best thing to do is to keep the mouth moist. One way to increase saliva production is to eat sugar-free gum or suck on sugar-free candies. Also, snacking on apples, celery sticks, and carrots can increase saliva production naturally.

6. Use Essential Oils

Certain oil extracts have also been found to reduce the incidence of bad breath by controlling the number of volatile sulfur compounds produced by different foods.

For example, a 2017 study found that cinnamon oil kills the S. moorei bacteria that cause bad breath. Impressively suggesting that it could be a game-changer in oral care items to fight bad breath. But the study also pointed out that care for cinnamon essential oil shouldn’t be placed directly on the skin or ingested. Instead, it should be diluted with a carrier oil to make it safer.

Another 2016 study found that tea tree oil can kill bacteria in the mouth that cause bad breath. This is similar to how chlorhexidine in mouthwash kills bacteria. To use, mix one drop of tea tree oil with vegetable oil in warm water, swish your mouth around for 30 seconds, and spit. Do not swallow it, as it is usually toxic to the body.

7. Use PrebioticsOrange 4 Ways to Overcome Bad Breath Instagram Post

Along with their many other benefits, prebiotics can also help prevent bad breath by supporting the growth of good bacteria. The University of Connecticut literature review also approved this. So, taking probiotics, using a probiotic-containing mouthwash, and keeping your mouth clean will all help strengthen your good oral bacteria.

Another best strategy is to add fermented foods like yogurt, sourdough bread, miso soup, and other natural foods such as bananas, which can actually help reduce bad breath with their prebiotic activity.

8. Reduce the Triggers

We now know that having bad breath and having a healthy gut are closely connected. It’s important to pay attention to what we put in our bodies. The best way to reduce halitosis is to avoid trigger foods. The most common trigger foods in such cases are,

  • Garlic
  • Milk
  • Onions
  • Canned tuna
  • Cheese
  • High sugar foods

We have compiled a table of the best and worst foods for halitosis below here,

Best Foods for Oral Halitosis Worst Foods for Oral Halitosis
Water Garlic and Onions
Yogurt (unsweetened) Dairy Products
Fruits high in vitamin C Coffee
Crunchy fruits and vegetables Alcohol
Green tea High-sugar foods
Parsley and other fresh herbs Processed Foods
Whole grains Acidic Foods
Nuts and seeds Spicy Foods
Fibrous vegetables Tuna and other Seafoods
Herbal teas Tobacco Products

9. Quit smoking and avoid tobacco products.

Just in case you needed more convincing, here’s an easy one: One of the causes of foul breath is smoking. Even after cleaning your teeth, the bad odor from tobacco might remain in your mouth. Tobacco also tends to dry up your mouth. So, all these factors do force you to quit smoking for good.

The same goes for alcohol. Although there are temporary solutions to cover up the unpleasant effects of alcohol, the most certain way is to remove it from your lifestyle completely.

10. Manage Systemic Conditions

Taking care of the underlying systemic conditions is very important for people with systemic halitosis. In this case, talking to doctors about stomach problems, diabetes, or other important diseases may be necessary.

When to Visit Doctor

Diagnosing bad breath from the mouth can take a bit more time. But you can check for any ongoing issues with digestion or bowel movements. If you encounter any of the following symptoms in addition to foul breath, it is necessary that you consult a medical professional without delay:

  • Belching or burping
  • Difficulty passing stool
  • Acid Reflux/Heartburn
  • Completely unable to defecate
  • Experiencing abdominal pain and cramping
  • Feeling uneasy
  • Throwing up

The root of bad breath isn’t always easy to pinpoint, and it’s not always as simple as forgetting to brush. So you can discuss your symptoms with your doctor and get to the bottom of what’s wrong. Note everything you’ve tried so far. That way, you can tackle the problem directly and strive for better breath!

As we wrap up our look at halitosis, keep in mind that oral health is only one part of our general health. Read our in-depth piece on body odor here for a broader view on how to deal with body odor and keep yourself clean.

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Dr Aimen

Being a Doctor by profession, Aimen is passionate about helping people get better health in their lives. Aimen enjoys her research on Prime With Time subjects and strives to create better awareness of the problems and changes related to women's health.
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