Persistent bad breath is usually caused by bacteria in the mouth, though it can also point to gum disease, decay, or other conditions.
Persistent bad breath, or halitosis, most often originates in the mouth itself — usually from bacteria breaking down food particles and dead cells on the tongue and between teeth. While often just an oral hygiene issue, persistent halitosis despite good hygiene can sometimes point to gum disease, decay, or occasionally a cause outside the mouth entirely.
The tongue, particularly the back portion, harbours the majority of odour-causing bacteria, which is why brushing teeth alone often isn't enough. Dry mouth, certain foods, smoking, and untreated dental problems can all contribute or make it worse.
Improving oral hygiene — including cleaning the tongue, not just the teeth — resolves most cases. If bad breath persists despite genuinely good hygiene, a dental check-up can identify and treat an underlying cause such as gum disease or decay that's driving it.
If it persists despite good hygiene, a dental check-up can identify and treat the underlying cause.
