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If you've followed the above steps diligently and the bad breath persists, you may have a medical issue that needs to be treated. Bad breath is a sign that something is not right in your body. If altering your hygiene practices and your diet does not improve your symptoms of bad breath, there is a good chance that there is some other imbalance, infection, or disease in your body that is causing it. These are lumps of calcified food, mucus, and bacteria that collect in the tonsils and can be seen as white spots. They are often mistaken for a throat infection such as strep throat, although sometimes they are too small to be visible in a mirror.  Tonsil stones are often harmless but cause a reeking bad breath. If you see a small white patch on the tonsil, try swabbing it gently with a cotton swab (be careful not to gag yourself, and don't press too hard). If it comes off on the swab and is a liquid or pus, you likely have a tonsil infection; however, if it doesn't come off or if it comes out as a solid chunk of white matter, it is likely a stone. Smell it and you'll know for sure. You might also notice a metallic taste in your mouth or an obstructed feeling when swallowing. If you have type 2 diabetes, it may be causing your body to burn fat instead of glucose, which releases ketones, a chemical that results in bad breath. Bad breath can be caused by metformin, a type 2 diabetes medication. If you take metformin, talk to your doctor about alternate treatment options. There are a vast array of illnesses that can cause halitosis, including the following:  Trimethylaminuria. If your body can't break down a chemical called trimethylamine, it will be released in your saliva, causing bad breath. It'll also be released in your sweat, so persistent body odor might be an accompanying symptom. Infection: Several types of infections such as sinusitis and infections of the stomach can result in bad breath. It is important to have any unusual symptoms checked out by your doctor, including this one.  Kidney disease or failure: In particular, a metallic or ammonia taste and scent to the breath can indicate severe problems with the kidneys. See your doctor if you have this symptom.
Talk to a doctor. Look for tonsil stones. Consider whether you have diabetic ketoacidosis. Consider other potential culprits.