Bad breath - common causes and treatments

Bad breath (or Halitosis) is a complaint I commonly hear when seeing patients, and is something they often come to the dentist to enquire about how to treat. There are many potential causes of bad breath. Here are some of the most common causes:

1. Bacteria in the mouth

A common cause of bad breath is an excess of bacteria in our mouth. Our mouths are normally home to billions of bacteria, some of which can release volatile sulphur compounds(1) causing an odour. Food debris and biofilm, as well as the back of the tongue are all breeding grounds for bacteria to grow. If these areas are not properly and regularly cleaned through a good oral hygiene routine, then bad breath can occur. 

2. Dental problems 

Bad oral hygiene can also lead to things like dental decay and gum disease. Bacteria can live inside cavities, gum pockets, and on plaque and calculus, which can then elicit inflammation from the gums (gingivitis and periodontitis) and bad breath.

3. Certain foods

Certain foods such as onion and garlic can create a bad odour by being absorbed into the bloodstream, and odours expelled by the lungs(2).

4. Medical conditions

One of the most common medical conditions that can cause bad breath is gastric reflux or indigestion. Acid and food from the stomach is brought up and can cause bad breath. Short-term this can be due to a reaction to certain foods or eating habits, such as eating foods just before bed. Long term this can be due to other medical issues that need to be addressed. Bad breath can also be a sign of a serious illness, such as diabetes, liver failure or kidney disease.

5. Dry mouth

Some medications, medical conditions, smoking and mouth breathing can contribute to having a dry mouth. The lack of saliva often means a lower clearance of bacteria and food debris, which can then result in further bacterial growth and bad breath.