A man checking his breath for signs of halitosis

The causes of bad breath (halitosis)

Bad breath – also known as halitosis, oral malodor and fetor oris – can be an embarrassing and uncomfortable condition. While it can be tempting to turn to mouthwashes, chewing gum, mints and other off-the-shelf products in an attempt to tackle the issue, these are typically only temporary remedies that simply mask the smell rather than remove it. In order to solve the problem of bad breath, you need to find and treat the root cause of the issue.

It’s important to remember that if you’re struggling to put your finger on the root cause of your halitosis, or you’ve found that simple self-care techniques such as regular teeth brushing and flossing don’t solve the problem, it might be time to visit your dentist, hygienist or GP to check your bad breath isn’t a symptom of a more serious health condition. However, before seeking medical advice, there are a number of common causes you should consider ruling out first.  

From certain food groups and health conditions to tobacco products and poor dental hygiene, there are many causes of bad breath. In this handy blog, we’ll run through some of the most common causes of halitosis and help you figure out why you might be suffering from this problem.[1]


Why do I have bad breath?

The primary cause of bad breath is a buildup of bacteria living in your mouth. When this bacteria interacts with the food you eat, as well as the natural proteins and skin cells in your mouth, they produce volatile sulfur compounds (VSCs). These compounds are what cause the release of a bad smell. However, the key to understanding bad breath is knowing what actually causes bacteria buildups. Only then can you decide upon and implement the best treatment to tackle your halitosis.[1]  

The most common causes of bacteria buildup and the resulting increased possibility of bad breath include:  

  • Bad dental hygiene

When you fail to brush and floss your teeth on a daily basis, food particles and sugars can remain on the surface of your teeth. While these particles can cause a bad odour in your mouth of their own accord, when they are not regularly cleaned away, they can also cause plaque to form on your teeth. When left to build up, this colourless, sticky film can fill the gaps between your teeth and around your gums, contributing to halitosis. Failing to brush your teeth or clean your dentures can also lead to odour-producing bacteria being trapped in your tongue and/or under your denture plate. It is also important to brush your tongue as 90% of bad breath is actually the result of the tongue being unclean. You can clean your tongue effectively by using an Orabrush tongue cleaner.[1]

  • Food particles

As mentioned above, one of the most common causes of bad breath is simply the food you eat. When food is broken down in your mouth the bacteria present can start to produce foul-smelling odours. The digestion of some foods, including the likes of onion, garlic, cheese and spices, can also lead to halitosis. This is because particles can enter your bloodstream during digestion and be carried to your lungs. These malodorous particles can then be smelt on your breath. You can help to prevent bad breath by removing food particles from your mouth through regular brushing and flossing.[1] 

  • Tobacco 

The simple action of smoking a tobacco product, whether that’s a cigarette or cigar, can leave an unpleasant odour in your mouth. However, on top of this, smokers also have an increased risk of gum disease – a primary source of bad breath.[1,2]

  • Dry mouth

Saliva helps to clean your mouth by breaking down and removing food particles that could cause bad breath. However, if your body starts to produce less saliva than usual, you can suffer from a condition called dry mouth (or xerostomia) – one symptom of this is bad breath. While many people experience dry mouth, or ‘morning breath’ as a result of sleeping with an open mouth, more chronic cases of xerostomia can be caused by an issue with your salivary glands or as a side effect of a certain medication you are taking.[3] 

  • Infection

Just as infections in other areas of the body can produce a foul odour, mouth infections can cause bad breath. Whether you have tooth decay as a result of poor oral hygiene that has led to an infection or gum disease, or you have picked up an infection following a surgical procedure in or around your mouth, bad breath can be a common side effect. Infections or inflammation in your nose, sinuses or throat can also cause bad breath.[2]

  • Serious health conditions

Although not as common as other causes listed above, other, more serious health conditions and diseases can lead to halitosis too. Some cancers, metabolic disorders, chronic acid reflux, diabetes and even kidney and liver failure can present with dry mouth and halitosis. For this reason, as discussed above, if you’re struggling to find the root cause of your bad breath, seeking professional medical advice is recommended.[1]


[1] https://www.nhs.uk/conditions/bad-breath/

[2] https://www.nhs.uk/conditions/gum-disease/

[3] https://www.nhs.uk/conditions/dry-mouth/

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