First.
Are you sure you have bad breath?
Is there any chance you have halitophobia ?
People with halitophobia are paranoid about the smell of their breath.
They often misinterpret other people's behaviour and comments, thinking they're suggesting they have bad breath.
They become obsessed with cleaning their teeth, chewing gum, and using mouth fresheners.
Here are some possible causes from the British National Health Service web site: Food and drink Eating strongly flavoured foods, such as garlic, onions and spices, is likely to make your breath smell.
Strong-smelling drinks, such as coffee and alcohol, can also cause bad breath.
Bad breath caused by food and drink is usually temporary.
It can be avoided by not eating or drinking these types of food and drink too often.
Good dental hygiene will also help.
Smoking Smoking is another cause of bad breath.
As well as making your breath smell, smoking stains your teeth, irritates your gums, and reduces your sense of taste.
It can also significantly affect the development of gum disease, another major cause of bad breath.
Stopping smoking will lower your risk of gum disease and help prevent bad breath.
Crash dieting Crash dieting, fasting, and low-carbohydrate diets are another possible cause of bad breath.
They cause the body to break down fat, which produces chemicals called ketones that can be smelled on your breath.
Medication
Some types of medication can also cause bad breath.
These include: nitrates – these are sometimes used to treat angina, chest pain caused by a restriction in the blood supply to the heart some chemotherapy medication tranquillisers (phenothiazines)
If the medication you're taking is causing bad breath, your GP may be able to recommend an alternative.
Medical conditions
In rare cases, bad breath can be caused by certain medical conditions.
In dry mouth (xerostomia), the flow and composition of saliva may be affected.
A lack of saliva can cause more bacteria than normal to build up in your mouth, as well as a change in the types of bacteria.
A build-up of these in the mouth may lead to bad breath.
Dry mouth can sometimes be caused by a problem in the salivary glands or by breathing through your mouth instead of your nose.
In some cases, gastrointestinal conditions can also cause bad breath.
For example, a bacterial infection of the stomach lining and small intestine (H. pylori infection) and gastro-oesophageal reflux disease (GORD) have been linked to bad breath.
If a gastrointestinal condition is thought to be causing your bad breath, you may need to have an endoscopy.
This is a procedure where a piece of equipment called an endoscope is used to examine an area inside the body, such as your airways or abdomen.
Other medical conditions that can cause bad breath include diabetes and lung, throat, or nose infections – for example, bronchiectasis, bronchitis, tonsillitis, and sinusitis.
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Breathing odor can be caused by food particles between the teeth.
So the use of dental floss may be appropriate.
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Try brushing your tongue.
From Colgate : You may brush twice a day and even sneak in an extra toothbrushing after lunch, but until you learn how to clean your tongue, you may not be able to get rid of lingering halitosis, or bad breath.
From Healthline : You brush and floss twice a day, but you could be doing your mouth a disservice if you aren’t also attacking the bacteria living on your tongue.
Whether it’s to fight bad breath or just for good dental health, cleaning your tongue is important, dentists say.
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Assuming there is no "smoking gun" you need to correct, there is one effective remedy I know of.
Flossing does help slightly, as does brushing with a toothpaste containing triclosan, but the only really big benefit I experienced came from using a mouthwash containing chlorine dioxide.
You can buy Smartmouth commercially, or you can prepare your own formulation as described in this paper .
If preparing your own, you may use a commercial mouthwash as a base, and you must measure pH. Also, don't mix the two parts until you're ready to use it.
If you mix your own, please don't buy the sodium chlorite from a quack.
There are people saying this chemical cures autism and cancer.
Those people don't deserve your money.
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Do you have dry mouth?
That could be a cause, if so.
There are several OTC products, like mouth washes, lozenges, toothpastes, etc, to help relieve it, and you can get them at any pharmacy store or Walmart/Target, and so on.
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Bad breathe occours in our mouth, when some food particles get deposited among our teeth or when we take some smell generating items like alcohol, tobacco,
spicy foods etc.
We should take the following steps to get rid of bad breath.1.Firstly, we should minimise the use of alcohol, tobacco, coffee and spicy foods.2.After taking any kind of food or meal, we should wash or rinse our mouth properly with water so that no food article remains deposited on or between our teeth.3.
We should make our habit of brushing our teeth daily twice, in the morning and at night before sleeping.
We should brush properly each tooth on front, back and top chewing surface with up and down strokes.4.
We should make our habit of flossing our teeth daily, before sleeping, with dental floss available from floss despenser.5.
We should clean our tounge also with a brush to remove bacteria.6.
We can use green tea which has antioxidants that reduce inflammation in gums.7.
Hydrogen peroxide can be used as a mouth wash or as a gel to kill bacteria with a precaution that it is not swallowed.8.If suffering from the gum disease, we can use warm salt water rinse.
It reduces inflammation and kills bacteria, but its daily use should be avoided as it will kill the teeth.9.
We should get our teeth checked every six months from a reputed dentist.
Some gas problem in the stomach can also cause bad smell from the mouth and we should take care of the stomach problem to remove the chances of bad breath.
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I brush multiple times in a day, use mouth wash as well. Take mouth fresheners multiple times. But, seem to never get rid of bad breath. I don't have bad gums either. Any suggestions?
How to get rid of bad breath
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There are many causes for bad breath, but it is generally agreed that many of them can be addressed by practising good dental hygiene, including flossing or brushing your tongue. On top of this, avoiding strong smelling foods and drinks may also reduce the risk of bad breath, and not smoking will also help. Bad breath can also be a sign of some gastrointestinal problems. The options are to check to see if you have halitophobia, check your diet for problem foods, practice good dental hygiene, avoid coffee and alcohol, stop smoking, take treatment for dry mouth if applicable, check any medications you are taking and check for problems with saliva glands or stomach, use dental floss, brush your tongue, use a mouthwash containing chlorine dioxide, try a dry mouth product and see a dentist regularly.
There are many causes for bad breath, but it is generally agreed that many of them can be addressed by practising good dental hygiene, including flossing or brushing your tongue. On top of this, avoiding strong smelling foods and drinks may also reduce the risk of bad breath, and not smoking will also help. Bad breath can also be a sign of some gastrointestinal problems.  Strong-smelling drinks, such as coffee and alcohol, can also cause bad breath, as do some medications and smoking. Good dental hygiene will also help. This includes having dental check ups every 6 months, using dental floss and brushing the tongue. Green tea has antioxidants that reduce inflammation in gums. Stomach problems can also cause bad smell from the mouth.
Good dental hygiene, regular dental checks, brushing your tongue, using dental floss and stopping smoking all help to avoid bad breath. Toothpaste with triclosan and mouthwash with chlorine dioxide are also recommended. To prevent bad breath, the main solution will be to maintain good dental hygiene, including flossing, mouth wash and regular trips to the dentist. You may also want to try brushing your tongue and, if applicable, stop smoking.
Check to see if you have halitophobia, check your diet for problem foods, practice good dental hygiene, avoid coffee and alcohol, stop smoking, take treatment for dry mouth if applicable, check any medications you are taking and check for problems with saliva glands or stomach. Use dental floss. Brush your tongue. Use a mouthwash containing chlorine dioxide. Try a product for dry mouth. See a dentist regularly and check for stomach gas problems.
 Strong-smelling drinks, such as coffee and alcohol, can also cause bad breath, as do some medications and smoking. Good dental hygiene will also help. This includes having dental check ups every 6 months, using dental floss and brushing the tongue. Green tea has antioxidants that reduce inflammation in gums. Some gas problem in the stomach can also cause bad smell from the mouth.
Good dental hygiene, including flossing and trips to the dentist will help prevent bad breath. You might want to try brushing your tongue. Flossing or mouthwash may be a good way to prevent bad breath. Stopping smoking will help prevent bad breath.