Why does bad breath happen?
Bad breath comes from sulfur compounds produced when bacteria in the mouth break down food debris, shed cells from the lining of the mouth, and blood from the gums. This gas, which smells like rotten eggs, is the main component of bad breath. So looking at where bacteria thrive — the back of the tongue, under the gums, and between the teeth — usually reveals the cause.
The smell when you wake up in the morning is physiological bad breath caused by reduced saliva during sleep. If it goes away after brushing and drinking water, that's normal. What I see as a problem in the treatment room is bad breath that comes back within an hour or two even after brushing.
Why do I have bad breath even after brushing?
Because the cause is somewhere the toothbrush doesn't reach. In order of how common they are, the causes are as follows.
| Cause | Typical signs | Where it's resolved |
|---|---|---|
| Tongue coating | The back of the tongue is covered with a white or yellow layer | Habit of cleaning the tongue |
| Gum disease (gingivitis, periodontitis) | Bleeding when brushing, swollen gums, teeth feel loose | Dental clinic: scaling, gum treatment |
| Cavities, gaps around restorations | Food gets caught in a specific spot, floss comes out smelling | Dental clinic: cavity treatment, replacing restorations |
| Dry mouth | Worse in the morning and afternoon, medication use, mouth breathing | Drinking fluids, checking medications that cause it |
| Tonsil stones, nasal conditions | Something felt at the back of the throat, yellow rice-grain-like lumps, stuffy nose | ENT clinic |
| Stomach or systemic conditions | With acid reflux or heartburn; rarely diabetes, liver, or kidney disease | Internal medicine |
If there's no cause in the mouth but the smell persists, that's when to see an ENT doctor or internal medicine. If you reverse the order, you may end up taking only stomach medicine and miss gum disease.
Is there a way to check my own bad breath?
Your nose quickly gets used to your own breath, so it's hard to notice it yourself. Instead, you can get a rough idea with the methods below.
- Floss smell: Smell the floss after using it. If it's strong only between certain teeth, suspect a cavity or gum problem in that area.
- Tongue check: Stick your tongue out in front of a mirror and look at the color at the back.
- Wrist test: Lick the inside of your wrist and smell it after about 10 seconds. This gives a rough sense of the front of your tongue.
- Ask someone close to you: This is the most accurate method.
How do I get rid of bad breath, and where do I start?
Start by cleaning your tongue and between your teeth. For most people, changing just these two things makes a noticeable difference.
- Gently clean the back of your tongue once a day with a tongue cleaner. I've explained how in How to use a tongue cleaner.
- Clean between your teeth once a day with floss or an interdental brush.
- Drink water often, and avoid alcohol-based mouthwash, as it can dry the mouth further. If you often have a dry mouth, also check the medications you're taking and whether you breathe through your mouth.
- If nothing changes after 2–4 weeks, have your tartar and gum condition checked at a dental clinic.
Mouthwash and gum only mask the smell for a while; they don't remove the cause.
How we do it at Wonjin Dental
When you come in for bad breath, I check gum depth, tartar, cavities, restoration margins, and the condition of the tongue in that order. If tartar is the cause, we start with scaling. Those aged 19 and over can get health-insurance scaling once a year; otherwise, scaling not covered by insurance is ₩60,000. If there is inflammation deep in the gums, it continues with gum treatment, which is mostly covered by insurance. If no cause is found in the mouth, I recommend seeing an ENT doctor or internal medicine.
Frequently asked questions
If I can see tonsil stones, will the dentist remove them?
Tonsil stones are a problem of the tonsils at the back of the throat, so an ENT clinic is the right place. Forcing them out with a cotton swab or similar can injure the tonsils. At the dental clinic, we can check whether there is also a cause in the mouth.
Tongue coating comes back even though I clean it every day. Is that normal?
The surface of the tongue is bumpy, so it's normal for coating to build up again every day. Cleaning gently every day matters more than scraping hard. Why it comes back is explained in more detail in Why tongue coating comes back.
What should I suspect if my bad breath suddenly gets worse?
If your gums have recently been swollen or bleeding, gum inflammation; if food gets caught on only one side, look first at a cavity or cracked tooth. If it follows a cold or rhinitis, it may be a nose or throat problem. Sometimes a newly started medication dries the mouth.
Can there be a smell around implants or crowns too?
Yes. If a gap forms at the margin of a restoration or the surrounding gums are inflamed, there can be a smell. If floss comes out with blood or a smell, get it checked.
