One of the many potential causes of bad breath is the tonsil stone, a collection of collagen and food matter at the back of the throat that forms a pungent ball or "stone." A French study conducted in 2007 found that approximately 6 percent of people have tonsil stones large enough to be detected on medical imaging scans.
Also called tonsilloliths, these stones begin as tiny food particles that get stuck in the folds of the tonsils. They increase in size as they accumulate more decayed food matter and as bacteria continually multiply on their surfaces. Tonsillitis may be a factor in the risk of tonsils stones. One study in the British Dental Journal found that 75 patients treated for the infection had tonsil stones, compared to 6 percent without it.
The smell of a tonsil stone is particularly powerful. Individuals who cough them up may be unable to stand the odor, and touching one may require repeated hand washings to eliminate the smell, which is caused by high concentrations of sulfuric compounds.
Rarely, a tonsil stone may lodge firmly enough to grow to a relatively large size. Medical studies have recorded tonsil stones up to an inch across. These are rare and typically require medical treatment.
To loosen small tonsilloliths, individuals may consider gargling with a specialty breath freshener, which may dislodge the stones and neutralize the compounds that cause halitosis.