The science of bad breath: understanding the causes

Bad breath, also known as halitosis, is a common and sometimes embarrassing problem that affects millions of people worldwide. Whilst most people experience bad breath from time to time, chronic halitosis can be a sign of underlying health issues.

The good news is that bad breath is often preventable and treatable with the right knowledge and habits.

In this article, we will explore the science of bad breath, including the causes and solutions. From understanding the role of bacteria in our mouths to identifying foods and habits that contribute to bad breath, we’ll provide you with the information you need to tackle this pesky problem head-on.

So, whether you’re dealing with bad breath yourself or simply curious about the science behind it, read on to discover the causes and solutions of bad breath.

Understanding the causes of bad breath

Bad breath can have various causes, including poor oral hygiene, certain foods, and underlying health issues.

The most common cause of bad breath is poor oral hygiene. When we don’t brush and floss our teeth properly, food particles can get stuck in our teeth and gums, leading to the growth of bacteria. These bacteria produce sulphur compounds that cause mouth odour.

Another cause of bad breath is the food we eat. Strong-smelling foods such as garlic and onions contain volatile compounds that can linger in our mouths and cause bad breath. Smoking and alcohol consumption can also contribute to bad breath.

In some cases, bad breath may be a sign of underlying health problems such as gum disease, respiratory infections, and digestive disorders. If you have chronic bad breath that doesn’t improve with good oral hygiene, you should see a dentist or doctor to rule out any underlying health issues.

The science behind bad breath

The science behind bad breath is fascinating. Our mouths contain millions of bacteria, some of which are good for our oral health, while others are harmful. When we eat, the bacteria in our mouths break down the food particles, producing sulphur compounds that cause bad breath.

Saliva plays a crucial role in preventing bad breath. It helps to wash away food particles and bacteria from our mouths, keeping our breath fresh. However, when we don’t produce enough saliva, our mouths become dry, which leads to bad breath.

Moreover, certain medical conditions can affect the salivary glands and the production of saliva, leading to dry mouth and bad-smelling breath. These conditions include diabetes, Sjögren’s syndrome, and Parkinson’s disease.

Types of Bad Breath Smells

Bad breath can present with a variety of distinct odours, each potentially indicating different underlying causes:

• Morning Breath: Often smells stale or sour due to reduced saliva production overnight, allowing bacteria to multiply.
• Food-Related Odours: Foods like garlic, onions, and certain spices can cause lingering odours, not just from particles in the mouth but also as their compounds enter the bloodstream and are exhaled through the lungs.
• Sweet or Fruity Breath: May indicate uncontrolled diabetes or a state of ketosis, where the body produces ketones that have a sweet or acetone-like smell.
• Rotten or Fetid Odour: Can be a sign of oral infections, abscesses, or decaying food trapped in dental appliances or cavities.
• Sour Breath: Often associated with acid reflux or gastroesophageal reflux disease (GERD), where stomach acids reach the mouth.
• Ammonia or Urine-Like Smell: May be linked to kidney problems, where waste products build up in the body and affect breath odour.

If you notice a persistent or unusual breath odour, especially one that is sweet, rotten, or ammonia-like, consult your dentist or doctor for further evaluation.

Common misconceptions about bad breath

There are several misconceptions about bad breath that people believe. One of the most common myths is that bad breath comes from the stomach. While some digestive disorders can cause bad breath, most bad breath comes from the mouth.

Another common misconception is that mouthwash is a cure for bad breath. While mouthwash can help to freshen your breath temporarily, it doesn’t address the underlying causes of bad breath. Moreover, some mouthwashes contain alcohol, which can dry out your mouth and make bad breath worse.

How to prevent bad breath

Preventing bad breath starts with good oral hygiene. You should brush your teeth twice a day and floss at least once a day to remove food particles and bacteria from your mouth. It’s also essential to clean your tongue regularly as the tongue harbours a significant amount of bacteria.

In addition to good oral hygiene, you can prevent bad breath by drinking plenty of water to keep your mouth hydrated. Chewing sugar-free gum can also help to stimulate the production of saliva, which prevents bad breath.

Solutions for bad breath: products and remedies

If you have bad breath, there are several products and remedies you can try. Mouthwash can help to freshen your breath, but you should choose one that doesn’t contain alcohol, as it can dry out your mouth. You can also try using a tongue scraper to remove bacteria from your tongue.

If you have a dry mouth, you can try using a saliva substitute to keep your mouth moist. Several over-the-counter products, such as lozenges and sprays, can help to freshen your breath.

Remember, however, that some of these solutions are only short-term fixes for treating bad breath. Using a mouthwash or sucking on a mint will mask the odour of bad breath in the short term, however, if you are not following a proper oral hygiene routine or you have underlying health issues, these products and remedies will not provide a long-term fix.

If you notice that you have bad breath more often than usual, it is best to make an appointment with your dentist sooner rather than later to identify the potential cause of the bad breath and put a plan in place to combat the problem.

Home Remedies for Bleeding Gums and Bad Breath

Bleeding gums and bad breath often go hand-in-hand, typically due to gum disease or poor oral hygiene. Here are some home remedies to help manage these symptoms:

• Brush and Floss Regularly: Gently brush twice daily and floss once a day to remove plaque and food particles.
• Use an Antibacterial Mouthwash: Choose an alcohol-free mouthwash to reduce bacteria without drying out your mouth.
• Saltwater Rinse: Rinse your mouth with a solution of warm water and salt to soothe gums and reduce bacteria.
• Eat Crunchy Fruits and Vegetables: Foods like apples and carrots help clean teeth and stimulate saliva production.
• Stay Hydrated: Drink plenty of water to keep your mouth moist and help wash away bacteria.
• Avoid Tobacco and Limit Alcohol: Both can irritate gums and worsen bad breath.

If bleeding gums persist for more than a week or if you notice swelling or pain, see your dentist promptly, as these may be signs of gum disease.

Foods that can help combat bad breath

Certain foods can help to combat bad breath. Crunchy fruits and vegetables such as apples, carrots, and celery can help to clean your teeth and stimulate the production of saliva. Yoghurt and other dairy products can also help to neutralise bad breath as they contain probiotics that balance the good and bad bacteria in your mouth.

Green tea is another excellent food for combating bad breath. It contains polyphenols that help to reduce the growth of bacteria in your mouth, leading to fresher breath.

When to see a dentist or doctor for bad breath

If you have chronic bad breath that doesn’t improve with good oral hygiene, you should see a dentist or doctor to rule out any underlying health issues. Your dentist or doctor will examine your mouth and may order tests to determine the cause of your bad breath.

Bad breath in relation to other health issues

Bad breath can be a sign of underlying health issues. For example, gum disease is a common cause of bad breath. If left untreated, gum disease can lead to tooth loss and other health issues.

Bad breath can also be a sign of respiratory infections such as pneumonia and bronchitis. In some cases, bad breath may be a symptom of digestive disorders such as acid reflux and lactose intolerance.

Summary

In conclusion, bad breath is a common and embarrassing problem that affects millions of people worldwide. While most people experience bad breath from time to time, chronic halitosis can be a sign of underlying health conditions. The good news is that bad breath is often preventable and treatable with the right knowledge and habits.

Understanding the causes of bad breath is the first step in preventing and treating it. Maintaining good oral hygiene, drinking plenty of water, and chewing sugar-free gum can help prevent bad breath. If you have chronic bad breath, it’s essential to visit your dentist or doctor to rule out any underlying health issues.

By following the tips and remedies outlined in this article and seeing your dentist regularly, you can keep your breath fresh and enjoy better oral health. Remember, prevention is always better than a cure, so take care of your oral health, and your breath will thank you!

FAQs

Why Do I Have Bad Breath After Brushing?

Experiencing bad breath even after brushing can be frustrating. Possible reasons include:

• Tongue Bacteria: The tongue harbours bacteria that produce odour; brushing your tongue or using a tongue scraper can help.
• Gum Disease: Brushing alone may not address underlying gum disease, which can cause persistent bad breath.
• Dry Mouth: Some toothpastes or mouthwashes (especially those with alcohol) can dry out your mouth, reducing saliva and allowing bacteria to thrive.
• Diet or Medical Conditions: Certain foods or health issues (like acid reflux) can cause bad breath that brushing doesn’t eliminate.

If bad breath continues despite good oral hygiene, consult your dentist to rule out other causes.

Does Dehydration Cause Bad Breath?

Yes, dehydration is a common cause of bad breath. Saliva helps cleanse the mouth and control bacteria. When you’re dehydrated, saliva production decreases, leading to a dry mouth where bacteria can multiply and produce foul odours. Drinking water throughout the day and avoiding excessive caffeine or alcohol can help maintain healthy saliva flow and fresher breath.

Post first published 14 August 2023 and last updated 16 April 2025