How do you know if you have bad breath?

One's own breath odour is often undetectable because you are used to it.

Many people will have an accompanying bad taste (metallic, sour, fecal, etc) in their mouth depending on oral dryness and the degree of breath odour.

A somewhat effective home method to determine the presence of bad breath is to lick the back of the wrist, let the saliva dry for a minute or two, and smell the result.

Another way would be to lightly scrape the posterior of the tongue with an inverted spoon or a piece of dental floss, and to smell the dried residue.

Alternatively, a spouse, family member, or close friend may be willing to smell one's breath and provide honest feedback.

Highly reliable home tests are now available which use a chemical reaction to test for the presence of polyamines and sulfur compounds on tongue swabs. Remember that breath odour changes in intensity throughout the day depending on many factors, so test several times.

If bad breath is persistent, and all other medical and dental factors have been ruled out, specialised testing and treatment might be required.

Hundreds of dental offices and breath clinics now use a portable sulfide monitor called the Halimeter to test for levels of sulfur emissions (specifically, hydrogen sulfide) in the mouth air. When used properly this device can be very effective at determining levels of certain VSC-producing bacteria. However, it has drawbacks in clinical applications. For example, other common sulfides (such as mercaptan) are not recorded as easily and can be misrepresented in test results.

Certain foods such as garlic and onions produce sulfur in the breath for as long as 48 hours and can result in false readings. The Halimeter is also very sensitive to alcohol, so one should avoid drinking alcohol or using alcohol-containing mouthwashes for at least 12 hours prior to being tested. This analog machine loses sensitivity over time and requires periodic recalibration to remain accurate.

New technology is now appearing in the form of portable gas chromatography machines such as the OralChroma, which is specifically designed to digitally measure molecular levels of the three major VSCs in a sample of mouth air (hydrogen sulfide, methyl mercaptan, and dimethyl sulfide). It is extremely accurate and produces visual results in graph form via computer interface.

Microbiological testing of swab samples of teeth and tongue residue remains the most accurate method of determining the specific bacterial causes of oral malodour.