Why do I have a bad taste in my mouth?
Short answer: A bad taste that keeps returning is usually caused by bacteria somewhere they should not be: gum disease, an infection around a tooth, food trapped under a failing filling, or dry mouth. A sudden foul, salty taste with relief from pressure often means an abscess has drained — that needs seeing promptly even though the pain has eased.
The usual causes
Gum disease
The most common. Bacteria in pockets below the gum line produce sulphur compounds — the same chemistry behind persistent bad breath. Usually accompanied by bleeding when brushing. See gum disease treatment.
An abscess that has drained
A sudden salty or metallic foul taste, often with the pain suddenly easing, can mean pus has found a way out. The relief is misleading — the infection is still there. Book promptly, and read swollen face if there is any swelling.
Food trapping
A failing filling, a gap opening between teeth, or a broken tooth creates a space food packs into and stays. Often noticed as a bad taste from one specific spot, and floss coming out smelling strongly from that gap.
Dry mouth
Saliva is the mouth's rinse cycle. Many common medications reduce it, as does mouth-breathing and dehydration. Less saliva means more bacterial activity and more taste.
Not dental at all
Reflux, sinus infections, some medications and some medical conditions can all cause a persistent bad taste. If your mouth is healthy on examination, that is useful information rather than a dead end.
What to do
Start with the mechanical causes, because they are the common ones: clean between the teeth daily — properly, not occasionally — and use a tongue scraper, since a large share of odour-producing bacteria live on the back of the tongue. Drink more water. Chew sugar-free gum if your mouth is dry.
What does not work is masking it. Mouthwash for a bad taste is treating the smoke alarm. Strong alcohol-based rinses can dry the mouth further and make it worse.
If a good routine has not shifted it in a couple of weeks, get it looked at — the cause is usually specific and findable. See also how to stop bad breath.
Common questions
What does a bad taste in the mouth mean?
Most often bacteria where they should not be — gum disease, an infection at a tooth, or food trapped under a failing filling. Dry mouth, reflux and some medications can also cause it.
I have a sudden salty taste and my toothache stopped. What is that?
That combination often means an abscess has drained. The pain easing is not recovery — the infection remains and needs treating. Book promptly, and seek same-day care if there is any facial swelling.
Can mouthwash fix a bad taste?
It masks it briefly. Strong alcohol-based rinses can dry the mouth and make the underlying problem worse. The cause is usually mechanical and needs finding.
Why does floss smell bad from one spot?
That usually means food is packing into a specific space — a failing filling, a gap between teeth, or a broken tooth — and stagnating there. It is worth showing your dentist exactly which gap.