Bad breath is one of those problems that feels frustrating, embarrassing, and weirdly hard to talk about.

You can brush twice a day, use mouthwash, chew mints, drink water, and still feel like your breath isn’t fresh. And what makes it worse is that most people don’t know whether it’s real or just anxiety.

Here’s the truth: persistent bad breath usually isn’t a brushing problem.

It’s often a sign that something else is going on in your mouth, gums, or even your overall health. And the sooner you identify the cause, the sooner you can stop wasting money on products that only mask the smell for 20 minutes.

This guide covers the 7 hidden causes of bad breath, plus when it’s time to see a dentist in Alexandra Hills.

Why Mouthwash Isn’t Fixing the Real Problem

Mouthwash can make your mouth feel minty, but it rarely fixes the cause of bad breath.

That’s because most mouthwash:

  • temporarily covers odour
  • doesn’t remove bacteria trapped under the gums
  • doesn’t clean between teeth
  • doesn’t treat infection or decay
  • can even worsen dry mouth (especially alcohol-based mouthwash)

If your bad breath comes back within an hour, that’s a sign the source is still there.

Think of mouthwash like perfume. It’s not cleaning the problem, it’s covering it. The smell may reduce for a short time, but the bacteria and buildup causing the odour are still present underneath.

If you’ve been relying on mouthwash daily and nothing is changing, that’s a strong sign you need to look deeper.

The #1 Cause of Persistent Bad Breath: Gum Disease

If bad breath keeps coming back, the most common cause we see is gum disease.

And it’s often present even when people think their teeth look fine.

When plaque and bacteria build up along the gumline, the gums can become inflamed and infected. This creates a smell that is:

  • persistent
  • sour or metallic
  • difficult to cover with mints
  • often worse in the morning

Gum disease also creates pockets around the teeth where bacteria thrive. These pockets trap debris and produce strong-smelling compounds, even if you’re brushing every day.

Signs of gum disease can include:

  • bleeding when brushing or flossing
  • red or puffy gums
  • gums that feel tender
  • plaque buildup around the gumline
  • bad taste in the mouth
  • gums pulling away from teeth over time

The tricky part is that gum disease is often painless at first. Many people don’t realise there’s a problem until the smell becomes noticeable or the gums start bleeding more often.

A professional scale and clean, along with gum treatment if needed, can make a dramatic difference, and it’s one of the fastest ways to reduce long-term bad breath.

Tonsil Stones: The Gross (But Common) Cause No One Talks About

Tonsil stones are one of the most overlooked causes of bad breath.

They’re small whitish lumps that form in the crevices of your tonsils, made up of food particles, bacteria, and dead cells.

And yes, they smell awful.

Some people have large visible tonsil stones, while others have tiny stones hidden deeper in the tonsils that still create strong odour.

Signs you might have tonsil stones include:

  • bad breath even after brushing
  • a constant bad taste
  • sore throat that comes and goes
  • feeling like something is stuck in your throat
  • coughing small white bits up occasionally
  • bad breath that seems worse when you wake up

Tonsil stones are very common, especially in adults, and they can cause strong odour even if your teeth and gums are healthy.

If you suspect this is the issue, we can still check your mouth and rule out dental causes first, which is always the best starting point. Many patients are relieved to learn their teeth are healthy, and that the cause may be throat-related instead.

Dry Mouth: The Silent Trigger Behind Morning Breath That Lasts All Day

Everyone gets morning breath.

But if it lasts all day, dry mouth may be the real issue.

Saliva is your mouth’s natural cleaning system. It helps wash away bacteria, neutralise acids, prevent plaque buildup, and reduce odour-causing compounds.

When your mouth is dry, bacteria multiply faster, and smells become stronger. Dry mouth also makes plaque stickier, which increases the chance of gum issues and decay over time.

Common causes of dry mouth include:

  • mouth breathing (especially during sleep)
  • snoring or sleep apnoea
  • dehydration
  • caffeine
  • certain medications
  • stress and anxiety
  • alcohol-based mouthwash
  • smoking or vaping

A lot of people don’t realise that mouth breathing at night can affect their breath all day. If you wake up with a dry tongue, sticky saliva, or a dry throat, this may be part of the problem.

If you wake up with a dry mouth and feel like your breath stays bad even after brushing, dry mouth is a major suspect, and it’s worth addressing early before it starts affecting your teeth.

Cavities & Old Fillings: When Tooth Decay Causes Odour

Bad breath isn’t always a gum issue.

Sometimes it’s caused by tooth decay.

Cavities can trap bacteria and food in areas you can’t reach with brushing. Over time, this creates a smell that can be rotten, sour, persistent, and worse after eating.

Old fillings can also cause issues if they:

  • crack
  • leak
  • trap food underneath
  • break down around the edges
  • leave small gaps where bacteria can sit

Many people have a cavity for months without pain, especially if it’s slow-growing. That’s why it’s possible to have “mystery bad breath” even when you don’t feel anything wrong.

If your bad breath has been lingering for a long time, a check-up and X-rays can help identify hidden decay. Fixing one cavity or replacing one failing filling can sometimes solve the issue immediately.

Your Tongue Might Be the Problem (Even If Your Teeth Are Clean)

Even if your teeth are spotless, your tongue can still be the main source of bad breath.

The tongue surface is textured, which makes it a perfect place for bacteria to live. Think of it like a carpet. You can vacuum the floor (your teeth), but if the carpet (your tongue) is holding bacteria, the smell will remain.

This bacteria produces sulphur compounds, which create that classic bad breath smell.

Signs your tongue is the culprit include:

  • a white or yellow coating on the tongue
  • breath that improves after tongue cleaning
  • a bad taste that returns quickly
  • a “furry” feeling on the tongue

What helps:

  • gentle tongue brushing once daily
  • a tongue scraper used carefully
  • drinking water regularly
  • avoiding smoking and vaping
  • reducing sugary snacks (which feed bacteria)

Tongue cleaning is one of the fastest improvements most people can make. It’s simple, it’s free, and it often works better than mouthwash.

Diet & “Healthy” Foods That Can Still Cause Bad Breath

A lot of people assume bad breath only comes from junk food.

But many healthy foods can still trigger odour, especially when eaten regularly or combined with dry mouth.

Common bad breath triggers include:

  • onions and garlic (even in salads)
  • tuna
  • eggs
  • coffee
  • protein shakes
  • low-carb or keto diets
  • citrus (in some people)
  • fermented foods
  • strong spices

Some foods release sulphur compounds. Others change your saliva balance or increase dryness. High-protein diets can also lead to a distinct keto breath smell.

Coffee is another big one. It dries the mouth and leaves compounds behind that can cling to the tongue.

If you’ve recently changed your diet and noticed bad breath started around the same time, this could be a big clue. The good news is that diet-related bad breath is usually manageable once you understand what’s triggering it.

When Bad Breath Means It’s Time to See a Dentist in Alexandra Hills

Bad breath becomes a dental issue when it is:

  • persistent for more than 2 to 3 weeks
  • noticeable even after brushing and flossing
  • paired with bleeding gums
  • paired with a bad taste
  • paired with sensitivity or pain
  • paired with swollen gums
  • affecting your confidence and social life

The best thing you can do is stop guessing and get a professional opinion.

At Alexandra Hills Dental, we can check for:

  • gum disease
  • plaque buildup
  • hidden decay
  • old fillings that may be leaking
  • infection
  • oral hygiene issues that are easy to miss at home

And if your mouth looks healthy, we’ll let you know and guide you on next steps, including when to speak to your GP if needed. Sometimes the cause is outside the mouth, but it’s still worth ruling out dental issues first.

If you’ve been feeling self-conscious, avoiding close conversations, or constantly worrying about your breath, you don’t have to keep living like that. This is one of the most common issues we help patients with, and it’s almost always fixable once you find the real cause.