Woman hiding mouth in jumper

What causes bad breath and what can you do about it?

Bad breath (halitosis) can be embarrassing, but you’re not alone – in some countries, up to half the population have issues with halitosis1. Once you understand what causes bad breath, and how to freshen breath, you can make positive changes.

We’ll explore the reasons and solutions for bad breath, including the potential link between oral probiotics, bad breath, and tongue bacteria2. Bad breath is usually easy to combat by taking care of your oral hygiene.  

What causes bad breath?

Bag of garlic

Some of the main reasons for bad breath3 include the following: 

  • Bacteria in the mouth: This can be on the tongue, gums or in between the teeth. It’s the main cause of halitosis for most people. 
  • Dry mouth: Saliva is naturally antibacterial and cleanses the mouth, so a lack of it can mean bacteria can grow rapidly. You might have a dry mouth because of dehydration or as a side effect of medication.
  • Medical conditions: These are uncommon reasons for halitosis, but it can be caused by sinus infections, tonsillitis, nasal polyps, dental abscesses, diabetes, acid reflux, and lung infections. You’ll usually have other symptoms too.
  • Medicines: Some medications can lead to bad breath. You can check if this might be the case by looking at the list of side effects and speaking with your doctor.
  • Strong-smelling food and drink: Spicy food, garlic, and alcohol, for example, can cause temporary bad breath because chemicals get into the bloodstream and are breathed out via the lungs.
  • Smoking: Chemicals left in the mouth after smoking can be a source of halitosis, so if you want to know how to remove bad breath, consider taking steps to quit smoking.
  • Dieting: Fasting, low-carb diets and crash dieting can be behind a bad smell on the breath, because when fat is broken down in the body it makes chemicals called ketones, which are then breathed out.

Most common cause of bad breath: bacteria

As we’ve discovered, a build-up of bacteria is one of the major reasons for bad breath. But why does halitosis arise from gum, tooth, and tongue bacteria? Bad breath in this scenario comes from the gases that bacteria release when they break down debris and proteins in the mouth.

You can get a build-up of debris and bacteria in the mouth due to:

  • Having a coating on the back of your tongue. This might be caused by postnasal drip (mucus from the back of your nose). Lots of bacteria can live on this coating.
  • Having particles of food stuck between your teeth. It can be hard to remove small bits of food with regular tooth brushing. As this food rots, bacteria increase.
  • Having dental plaque or tartar on your teeth. When bacteria, saliva, and food combine, they form plaque, which is full of bacteria.

How can you deal with bacteria? Although it might sound unpleasant, it’s actually easy to tackle, with good oral care practices. You might have heard about halitosis probiotics too and want to know what probiotics are good for bad breath, so let’s explore that now.

Prebiotics and probiotics for bad breath

We have both good and bad bacteria in the mouth, and having the right balance of the two will help keep your gums and teeth healthy, and your breath smelling fresh. As Dentist Surina Sehgal explains ''In the oral microbiome, organisms associated with health exist side-by-side with those associated with disease.''

Maintaining a state of harmony with your oral microbiome is crucial, to prevent the overgrowth of disease-associated bacteria and keep oral problems at bay.
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Dentist Surina Seghal

So, you want to eat foods with probiotics for bad breath to be kept at bay. But what’s the difference between oral probiotics and prebiotics? Put simply, probiotics are good bacteria, whereas prebiotics are ingredients that feed good bacteria. Bad breath can be managed when we help the bacterial ratio. Examples of probiotics for bad bread include: 

  • Fermented foods such as kefir and kimchi 
  • Yogurt 
  • Tempeh 
  • Sourdough bread

How to freshen breath

Zendium Extra Fresh Toothpaste

Freshen Breath by having a thorough oral hygiene regime to clear away bad breath bacteria: 

  1. Gently brush teeth and gums for two minutes twice a day  
  2. Floss between your teeth daily (or use interdental brushes) 
  3. Clean your tongue daily with a tongue scraper  
  4. Attend regular dental check-ups  
  5. Use oral care products that help keep your mouth naturally healthy 


Extra tips for how to remove bad breath4 include:  

  • Keep hydrated 
  • Eat less strong-smelling food and alcohol  
  • Limit the amount of sugary food and drink you consume (these encourage bacteria in the mouth)
  • Chew sugar-free gum if you have a dry mouth 
  • Avoid smoking 
  • Get treatment for medical conditions that might be the cause

The natural antibacterial enzymes and proteins in Zendium’s Extra Fresh Toothpaste have a prebiotic benefit, by supporting a healthy environment that helps to combat bad bacteria and boost good bacteria. Its mild formulation supports the mouth’s natural defences gently and effectively, and it is clinically proven to give you naturally fresher breath for up to 12 hours.


1 Patient Access – Bad Breath: Halitosis

2 Halitosis: The Multidisciplinary Approach

3 Patient Access – Common Causes of Bad Breath

4 NHS – Bad Breath

The advice in this article does not constitute medical advice; it is solely available for information purposes. We recommend that you consult your dentist if you are experiencing any tooth or gum problems.