Author: Lizzie Smith – blog last updated on Wednesday 6th December 2023

There are many possible causes for halitosis, or bad breath, as it’s more commonly called. It used to be thought that the odour mainly came from the stomach. But today, it’s known that 85% of cases of bad breath originate from the oral cavity. In this article, we’ll look at the possible causes of bad breath.

Causes of bad breath in the oral cavity

1. Plaque and deposits on the tongue

Both plaque and the yellow or white deposits on the back of your tongue are a mixture of saliva, food residues and bacteria. They’re anaerobic bacteria, which means they thrive in an oxygen-poor environment. They live on sugars and carbohydrates, which they convert into sulphurous gases. The more harmful bacteria are in your mouth, the more smelly substances such as methanethiol, ammonia, and hydrogen sulphide are produced. 

Most people remove plaque from their teeth twice daily. Ultimately, that’s the purpose of brushing your teeth. But the tongue is often forgotten. So, even if you clean your teeth properly, you can still have bad breath due to a thick layer of deposits on your tongue.

white tongue coating

2. Gingivitis

If you don’t completely remove plaque from your teeth, for example, by only brushing and not flossing or brushing, this will not only make your breath more unpleasant, but the plaque that remains between your teeth can smell. You also run a greater risk of tooth decay and inflamed gums. Harmful bacteria also flourish in an infection, contributing to bad breath.

3. Disturbed oral flora

Not all microbes in your mouth are harmful. Most of them are actually very useful and contribute to a clean mouth and healthy digestion. To achieve this, the oral flora must be in balance, otherwise harmful bacteria will proliferate. They then produce even more smelly gases, which you exhale. In addition, you may get a metallic taste in your mouth, and the fungus Candida albicans can cause an oral fungal infection.

4. Tonsil stones

Almond stones or tonsil stones are smelly white or light yellow lumps. They can form in the tonsil crypts and the grooves of your tonsils. Tonsil stones also contain anaerobic bacteria, which feed on mucus, blood cells and minute food residues within the stone. Their abundant food supply leads to the excretion of smelly sulphurous gases. That’s why almond stones smell really bad, and you’re exhaling that smell.

bad breath tonsil stones

5. Dry mouth complaints

Regardless of the cause, a shortage of saliva will always help harmful bacteria to thrive. Saliva contains oxygen precisely to keep these types of bacteria under control. So, a dry mouth is often accompanied by bad breath.

Causes of bad breath in the rest of the body

1. Bacteria in the nasal cavity

Just above the mouth, in the nasal cavity, bacteria can also cause bad breath. For example, when you have a cold or sinus infection, so many bacteria can be present that the nasal mucus starts to smell.

Then there’s the post-nasal drip. This natural reaction ensures the nasal mucus that doesn’t come out through the nostrils drips into the pharynx. That may not sound so fresh, but it ensures the pressure in the nasal cavity doesn’t become unbearable.

solutions bad breath

2. Diet and fasting

Dieting or fasting can quickly cause bad breath. For example, with a low-carb or keto diet (minimal carbohydrate intake), the body burns fat to obtain energy. Ketones are produced, which are used as energy for body processes instead of carbohydrates. During these processes, acetone is released, which is excreted through respiration and urine. Hence, a specific acetone smell exists in people on a low-carb diet.

This process can also take place during fasting. In addition, a dry mouth, for example, due to not being allowed to drink during Ramadan, can cause bad breath.

3. Zenker diverticulum

A Zenker diverticulum is an abnormality in the oesophagus. It’s a bulge – a kind of bag that hangs on the oesophagal wall. Food sliding down the oesophagus can end up in the diverticulum. These food remains can then rot, which doesn’t smell so fresh.

cure bad breath

4. The sphincter between the oesophagus and stomach doesn’t close properly

If the stomach isn’t closed correctly, stomach acid and foul-smelling gases can rise from the stomach. A poorly closing sphincter muscle often occurs with a diaphragm hernia. That isn’t an actual fracture but a weakening of the diaphragm – the separation between the chest and abdomen. This certainly isn’t rare, as it’s estimated 40 per cent of people over 60 suffer from it. This condition, also called “sliding hernia,” can cause heartburn (reflux) and bad breath. Yes, it’s annoying. But, fortunately, it’s not severe.

5. Helicobacter Pylori

The bacterium Helicobacter Pylori doesn’t cause lasting problems for most people. It’s striking that people with this bacteria in their stomach almost always suffer from bad breath. It’s not the bacteria that smells, but its presence seems to cause more smelly gases in the digestive tract. If Helicobacter Pylori is found in someone, they’ll immediately be prescribed a course of antibiotics.

6. An unbalanced intestinal flora

Like the oral flora, intestinal flora is a community of bacteria and other microbes that must keep each other in balance. Most of the bacteria in the intestines are useful and downright indispensable because they’re the ones that digest your food. If everything is in balance, there’s nothing wrong. But just like in the mouth, the balance of intestinal flora can be disturbed. This often happens during a course of antibiotics. However, one-sided nutrition due to a strict diet or neglect can disrupt the balance.

Temporary imbalances can usually be corrected with probiotics, yoghurt, kefir or other fermented milk products.

7. Blockage of the intestines

Gases are released in the intestines during the digestion of food. That’s normal, but they don’t come out through your mouth. If stool remains in the intestines for too long due to a blockage (constipation), it can ferment. Sulphur gases are then released, which the body must get rid of. The gases pass through the intestinal wall via the bloodstream into the lungs. They only have to be breathed out there, which obviously doesn’t smell very nice.

8. Metabolic diseases

In metabolic diseases, foul-smelling gases can also enter the bloodstream and be exhaled through the lungs. This is called alveolar gas exchange. In the condition of trimethylaminuria, for example, the substance trimethylamine is not broken down or isn’t broken down sufficiently.

The body must then excrete the substance through sweat and urine. That wouldn’t be so bad if it weren’t for the fact that trimethylamine smells like fish. People with this condition, also called fish odour syndrome, smell like fish, which leads to problems in dealing with others. The only cure for an overly pungent fishy smell is a diet that omits foods that are easily converted into trimethylamine.

9. Kidney and liver diseases

If the kidneys don’t work correctly, too many waste products remain in the body, circulating in the blood. The liver also has the task of filtering waste products from the body.

If one of these organs doesn’t work correctly, the waste must be discharged differently. They often end up in the lungs and leave the body through exhalation. Obviously, that doesn’t make the breath any fresher.

prevent bad breath

How to combat bad breath

Because, in most cases, the cause of bad breath is in the oral cavity, you can often solve this with better or more extensive oral hygiene.

  • Brush your teeth at least twice a day.
  • Use dental floss, dental arches, toothbrushes or sticks once a day to remove plaque between your teeth.
  • Rinse your mouth daily with a good mouthwash.
  • Choose toothpaste and mouthwash without alcohol and harmful chemicals. Use oral-friendly products that support your oral flora instead of disrupting it.
  • Clean your tongue daily with a tongue scraper, a special tongue brush or a tongue cleaner that combines these functions.
  • Treat dry mouth complaints.
  • Treat irritated gums before they become gingivitis
  • Don’t neglect your oral hygiene when you’re sick, but extend it to your nose with natural, non-addictive nose drops 
  • Visit the dental hygienist and dentist regularly for professional check-ups and cleanings
  • Check your tonsils for tonsil stones and remove them if necessary

RyttPro Fresh Breath Kit

With this RyttPro total package for fresh breath, you can kill several birds with one stone. It contains RyttPro Toothpaste, RyttPro Mouth Spray and RyttPro Mouthwash. The active formula of these products is based on a combination of active oxygen (stabilised chlorine dioxide), CPC (cetylpyridinium chloride) and zinc. Together, they effectively tackle harmful bacteria whilst respecting a  balanced oral flora. 

solutions bad breath

Naturally, these products protect your teeth against caries (cavities) while hydrating and caring for the soft tissues in your mouth. The mouth spray helps care for your teeth and freshen your breath during the day or while travelling.

The Kit also contains the RyttPro Tongue Cleaner – an effective tongue cleaner that’s a tongue scraper and tongue brush in one.

tongue cleaner


If you still suffer from bad breath after following these measures, it’s advisable to consult your doctor. They can refer you to a specialist to examine and treat the cause.


British Dental Association:  Improving oral health

British Dental Journal: Help your patients tackle bad breath