Bad breath that won't go away
You brush, you floss, you chew mint. Within an hour the smell is back. Other people may notice it before you do.
Breath that keeps coming back is not a cleaning problem alone. It usually means germs are living somewhere your brush does not reach. The two most common spots are the back of the tongue and the pockets under the gum line.
This page sits under gum disease because deep gum pockets are a top cause of long-lasting bad breath. But they are not the only cause. The rest of this page helps you tell them apart.
When to see someone
Book a dental visit if the smell lasts more than two weeks after you start cleaning your tongue and between your teeth.
See a dentist within days for gums that bleed most times you brush, gums that look pulled back, or a bad taste that will not go.
See a dentist urgently for pus at the gum line, an adult tooth that feels loose, or a gum lump that hurts.
Go to urgent care or an emergency room for face or jaw swelling, fever with mouth pain, trouble opening your mouth, or trouble swallowing or breathing. A tooth infection can spread fast.
See a doctor for a sore or white or red patch in the mouth that has not healed in two weeks. Also see a doctor for a lump in the neck, a hoarse voice for more than three weeks, or coughing up blood.
See a doctor the same week for fruity breath with heavy thirst, lots of peeing, and weight loss. That can be high blood sugar and it needs a test.
See a doctor if a young child has a smelly nose on one side with thick discharge. An object may be stuck up the nose.
Tell your doctor if a new drug dried your mouth out. There is often another choice or a way to help.
Why it happens
Your mouth holds many kinds of germs. Some of them feed on bits of food, dead cells, and blood. As they feed, they give off sulfur gases.
Those gases are what people smell. They can smell like rotten eggs, old cheese, or a drain. Even a small amount carries a long way.
In gum disease, the gum pulls away from the tooth and makes a small pocket. That pocket is warm, dark, and low in air. It is a near perfect home for the germs that smell the worst.
The back of the tongue works the same way. Its surface is rough and holds a soft coating. Germs sit in that coating all day.
What else it could be
Gum disease. The smell is steady and often worse near one part of the mouth.
Look for gums that bleed when you brush, gums that pull back from the teeth, or a bad taste that will not shift. A tooth may feel loose or your bite may feel different.
Tongue coating. The smell is strongest in the morning and comes back through the day.
Look at the back of your tongue in a mirror. A thick white or yellow film points this way, and gums look fine.
Dry mouth. The smell rises when you are quiet, asleep, or on a long drive. Spit washes germs away, so less spit means more smell.
Many drugs cause it, including ones for blood pressure, allergy, pain, and low mood.
Tonsil stones. You may cough up small white or yellow lumps that smell awful when crushed.
Your throat may feel like something is stuck in it. Teeth and gums can be perfectly healthy.
Sinus drip or sinus infection. Mucus runs down the back of your throat and feeds germs there.
You may have a blocked nose, a night cough, or facial pressure. In a young child, a smelly nose on one side only can mean an object up the nose.
Reflux. Acid and food gas come up from the stomach. Expect burning in the chest, a sour taste, burping, or a hoarse voice in the morning.
Reflux is blamed for bad breath far more often than it deserves.
Food, smoking, and alcohol. Garlic, onion, and some spices leave the body through the lungs for a day or so.
Brushing will not stop that, because the smell is coming from your blood, not your mouth. Smoking adds its own smell and also raises gum disease risk.
Low-carb or keto eating and fasting. Breath may smell sweet, fruity, or like nail polish. This tracks with your diet, not your brushing.
Rare but serious. Breath that smells fruity with heavy thirst and weight loss can point to high blood sugar.
A fishy or ammonia smell can point to liver or kidney trouble. These come with other body symptoms, not just breath.
How to read the grades below
The options below come from our page on Gum Disease (Periodontitis). Each one carries two labels.
The first label is the evidence grade. A means strong trials in people, B means smaller or mixed studies, and C means early or limited findings. D means lab work only, and “insufficient” means the research cannot settle it yet.
The second label is the traditional tier. T3 means long use in more than one tradition, T2 means long use in one, and T1 means known use. T0 means no such record.
These grades come from research on Gum Disease (Periodontitis), the parent Health Topic, not on bad breath that wont go away.
A grade tells you how strong the research is, not how well something will work for you. Talk to a doctor or pharmacist before you start anything, above all if you take other medicines.
What to try first
Start with the tongue. Most of the smell lives there. A tongue scraper or a soft brush is one option for cleaning the tongue.
Start at the back. Pull forward. Rinse the tool.
Do this once a day.
Brush twice a day. Clean between your teeth once a day.
Floss or small gum brushes are two ways to clean between the teeth. A brush alone misses the gum line.
Sip water all day. A dry mouth smells worse. Chew sugar-free gum to make more spit.
Skip harsh mouthwash with alcohol. It dries the mouth. The smell can come back stronger.
Try a Saltwater Rinse. It has an evidence grade A and a traditional tier T3. Stir half a teaspoon of salt into a cup of warm water.
Swish for 30 seconds. Spit it out. Do this once or twice a day.
If gums are the cause, get a dental cleaning. No rinse or pill takes the place of that. The germs sit under the gum, out of reach.
Some options are used to help gum health. Lactobacillus reuteri has an evidence grade A and a traditional tier T0. Probiotics (Lactobacillus plantarum P8) has an evidence grade C and a traditional tier T0.
Aloe Vera Topical has an evidence grade B and a traditional tier T3. It is used as a gel on the gums. Cranberry extract has an evidence grade A and a traditional tier T1.
Spirulina has an evidence grade B and a traditional tier T1. Ubiquinol/Coenzyme Q10 (CoQ10) has an evidence grade B and a traditional tier T0. Melatonin has an evidence grade A and a traditional tier T0, studied for gum health.
Four more are used with much weaker proof. Turmeric has an evidence grade insufficient and a traditional tier T3. Green tea extract (Camellia sinensis) has an evidence grade insufficient and a traditional tier T3.
Resveratrol has an evidence grade insufficient and a traditional tier T0. Omega-3 (EPA/DHA Fish Oil) has an evidence grade insufficient and a traditional tier T0. Insufficient means we do not yet know if they work.
Ask your dentist or doctor before you add any of these. Some can affect drugs you take. None of them can promise your breath will change.
How long it takes
If the tongue is the cause, daily scraping often helps within two or three days. If nothing changes after a week of good cleaning, the cause is likely somewhere else.
If gum disease is the cause, expect weeks, not days. A deep cleaning at the dentist is usually the turning point. Gums often stop bleeding two to four weeks after that, and the smell fades as they settle.
Dry mouth improves as soon as spit flow improves. Food smells like garlic clear in about one to two days on their own. Tonsil stones and sinus drip come and go, so the smell may cycle rather than fade.
Give any supplement you try a fair window of about eight to twelve weeks. Keep doing your basic cleaning the whole time. Stop anything that upsets your stomach or gives you a rash.
