Use the table of contents below to jump to each section as needed.

i. First things first – cover the basics and do them well

If you are 100% confident that you have nothing to learn about the basics (flossing, scraping, NOT rinsing, hydration), then jump to the lesser-known reasons here.

1. Flossing

If you haven't started flossing yet, this is your first port of call – and it becomes a non-negotiable for the rest of your life.

Flossing is about removing the biofilm and bacteria that's breeding between your teeth. Smell your floss and you'll find a culprit for your bad breath, often coming from specific teeth.

Twice a day, morning and evening, and do it BEFORE brushing. Learn how to do it properly (YouTube video guide).

Everyone will experience bad breath if they aren't flossing, so this needs to be a standard daily practice. If you're flossing and still have bad breath (which is likely in the case of a chronic issue), then...

2. Tongue scraping

Invest in a metal tongue scraper, and use it morning and evening. Rinse the scraper after each pass down your tongue. After scraping, rinse your mouth with cold water and spit it out.

Everyone gets debris on their tongue, but for those who have a particularly high amount of it, that is often a symptom of a deeper problem. Either way, it's still important to control the symptom and get rid of it daily.

Tongue scrapers are affordable. Buy one immediately, and use it daily (Amazon results for tongue scrapers).

3. Stop rinsing after brushing

Brush your teeth, spit out the excess, get the froth off of your lips and chin, then STOP.

Keep the thin layer of toothpaste in your mouth and on your teeth. It continues to both strengthen your teeth and tackle any remaining bacteria in your mouth.

You end your cleaning routine here. Floss > Scrape > Rinse > Brush > Spit > NO RINSE. That includes mouthwash.

4. Hydration

If you're not drinking water, your mouth is going to get dry. You don't need to know all the details – just know that dry mouth = higher likelihood of bad breath.

Hydrate. A small glass every hour is enough. Just make sure your first glass is at least 30 minutes after you brushed.

ii. The lesser-known reasons for bad breath and their solutions

The lesser-known reasons are tonsil stones, mouth guard hygiene, sinuses and their structure, and acid reflux. Look into these things immediately and get them under control – there is a high likelihood that your problem is found here. 

1. Tonsil stones

Do you have tonsils? If no, skip to point 2. If yes, this should absolutely be your #1 suspicion for the cause of your chronic bad breath.

Get a flashlight, stand in front of a mirror, open your mouth, and start getting familiar with the back of your throat. 

Your tonsils are located approximately in-line with your uvula (the small hanging 'tongue'), found to the left and right of it tightly against your throat walls. 

Depending on your tonsil structure, you might immediately notice some white areas on them. Those are tonsil stones. For most people, you'll need to poke them a bit either with a tonsil stone kit (examples on Amazon here) or with a clean finger.

If you poke and pull them a bit, a stone might show itself or even pop out. If you have exceptionally deep or complicated 'crypts', you might just see a white foam-like substance come out that looks a bit like saliva (but isn't). That's a sign that stones are there.

After looking around with your finger, smell it. If your sense of smell is typically reliable, you will likely find a bad smell on your finger. That's another sign that the stones are there.

Some other quick, easy signs of tonsil stones that may or may not be present...

• A bad taste in the back of your mouth

• Feels like something is stuck in the back of your throat

• Throat irritation

• Swollen or inflamed tonsils

There are some communities on Reddit where you can learn more and figure out if this is what's affecting you. Here is r/TonsilStones (NSFW) and here is r/Tonsillectomy.

The solution to tonsil stones?

There are a few things you can do about tonsil stones, ranging from least to most effective.

(Least effective)

• Remove them manually daily with a tonsil stone removal kit. Tonsil stones are likely to appear at least weekly, so as you remove them more will start to develop, and it's unlikely you'll be able to remove them all at once.

• Use a therapeutic mouthwash. Brands like TheraBreath receive particularly high praise from r/TonsilStones, but of course the effects wear off and doesn't address the root cause.

• Improved oral hygiene, described at the top of this page. This helps reduce bacteria and debris in your mouth, and slows down the formation of tonsil stones, but doesn't cure the problem or address existing stones.

• Salt-water gargles are anti-septic and the motion can help dislodge stones, reduce inflammation, and reduce bacteria. Quite unreliable and hard to measure the results.

• Specific dietary changes, particularly reducing mucous-producing foods from your diet like milk and cheese, and increasing your hydration so there's less debris that can find its way into your tonsils.

(Moderately effective)

• Laser tonsillectomy. A laser tonsillectomy basically closes up the gaps in your tonsils and smooths them over, leaving less or little space for stones to develop. In some cases you can totally remove the tonsils while leaving the bed of the tonsil in place. This often requires multiple sessions, and there is risk that your tonsils develop more crypts or have some crypts left, which is quite a problem.

• Water flossers, used at low-pressure settings, can flush out tonsil stones. It's safer, more thorough and less irritating to the tonsil than the usual removal kit, but you need to do this frequently and the stones will continue to form.

(Most effective)

• Standard tonsillectomy. Just get the tonsils removed entirely from your throat. You can find endless relief and success stories within r/Tonsillectomy, and how this has totally changed people's lives for the better. The surgery and recovery is tough, but the benefits are long-lasting and well worth it. If you have tonsil stones and are serious about fixing this problem, speak to your healthcare provider and seriously consider this as your solution. If tonsil stones were an issue for you, then you will also find that you have far less to scrape off your tongue in the mornings after you recover from the tonsillectomy.

2. Mouth guards, dentures, retainers, bite plates – anything you sleep with in your mouth needs to cleaned

Bacteria gathers on your mouth piece during the night. If you rinse and leave it during the day, the mouth piece dries out and the bacteria multiplies. Each night you put it in your mouth, you make the problem worse and it transfers into your mouth's ecosystem.

Your mouth piece might not even smell – yet. But eventually it will, and by then it's far too late – your mouth and breath will already be noticeably bad. So control it – early and often. You need to wash it every single day. Not just a rinse under warm water – it needs to be properly and deeply cleaned.

Three ways you can clean your mouth piece...

• Brush it with a very very soft toothbrush and non-grainy toothpaste. Be very careful with this option, because a toothbrush that's too hard or a grainy toothpaste can leave micro-scratches in your mouth piece, which then become a breeding ground for bacteria that is nearly impossible to get rid of.

• Use mouth guard cleaning tablets. Here is a product randomly found on Amazon to show you what to look for. You just leave your mouth piece to soak for a while, and you're good to go. This is effective and should be good enough to keep bad breath at bay.

• Use an ultra-sonic cleaning device. These use ultra-high frequency shockwaves to basically dislodge bacteria and other debris from your mouth piece. It's gentle yet thorough, and prevents any scratches or damage on your mouth piece. This is best used together with cleaning tablets. If you take this route, you are 100% covered from bad breath from a mouth piece. Here are search results on Amazon.

3. Sinuses and their structure

Your sinuses are the drainage system for fluids and mucous in your head.

If your sinuses are particularly narrow, deviated or restricted, or even if your adenoids are too large, you will have a host of problems – bad breath included.

This bad smell can either come from your nose or your mouth, and it can be hard to tell which of the two.

If you often experience sinusitis, pressure in your face from blocked sinuses or feel clogged up, this could be you.

Unfortunately, the only way to test this is to go to an ENT (Ear, Nose and Throat doctor) to check on...

• The size of your adenoids, which can block the flow of fluids. These can be removed through an adenoidectomy, often done in tandem with a tonsillectomy.

• The structure of your sinuses, usually done via X-Ray.

• Your throat, to see if you have a persistent post-nasal drip. If you do have one, this is a key cause of bad breath, and it's usually a consequence of the first two points (adenoids and sinus structure).

If your sinus structure has issues, there are a few things that can be done. These can include surgeries to increase the size of your sinuses so the fluids can flow better, or correcting the pathway if there's a deviation. Depending on your ENT, surgery may be seen as a last-line solution. Whatever it is, solutions exist, and you should explore it and seriously consider it with your ENT.

4. Acid reflux (also known as GERD)

GERD is a condition where stomach acid flows back into your esophagus because the 'valve' between your throat and stomach doesn't close well enough.

Signs that you have GERD are usually heartburn or the feeling of your food 'coming back up', sometimes unpleasantly into your mouth. In reality it could be food particles, digestive enzymes or bacteria. The acid itself has a sour odor to it, and it basically irritates your throat, dries out your mouth, and encourages bacteria growth in your mouth.

To figure out if you have GERD, visit a gastroenterologist. Even if you don't recognize the key signs of GERD in yourself, the gastroenterologist can check if you have key signs of it like burns or inflammation in your throat from the acid, and a variety of other tests including looking into your digestive system.

Before you get to the gastroenterologist, you can also try a few 'GERD-reducing' steps to see if you notice any improvement. These include...

• Raising your head/chest higher when you sleep, which basically keeps the acid down.

• Eat smaller meals and avoid lying down for 2 - 3 hours after eating, to reduce the chances of back-flow and make it harder for the acid to flow up.

• Try a short course of over-the-counter antacids and see if you notice any difference in either your breath or your symptoms.

• Identify your trigger foods, which are often spicy food, alcohol, caffeine, tomato sauces or citrus. Your triggers will be unique, so pay attention to your body.

iii. Dental-related reasons for bad breath

These are easily identified and fixed at a decent dentist. As such, they don't require much detail but you should be aware of them and explicitly rule these out as causes together with your dentist.

1. Gingivitis (mild gum disease) and periodontitis (advanced gum disease)

Plaque buildup forms around the teeth and causes inflammation of the gums. The bacteria from the plaque gives off bad odors, resulting in bad breath. With gingivitis, your gums will look red and they'll typically bleed from flossing or brushing. If untreated, it develops into periodontitis where the infection spreads to deeper tissues. The bacteria starts to build up in deeper pockets, and there you are – chronic bad breath.

2. Cavities and broken fillings

Food gets trapped in the holes in your teeth, breeds, and gives off bad odors. Pain, sensitivity, visible holes or rough-textured teeth are key signs of this.

3. Dead and rotting teeth

A dead tooth starts at the nerve – when the nerve dies, it can become infected and start producing pus and bad odors. If the tooth is simply rotting but the nerve is still alive, the bacteria will produce sulphur compounds and give you bad breath.