Bad breath is a concern for most of us. It creates worry in social situations, and can make it hard to feel comfortable talking to people. You never want to get close to personal or business acquaintances if you can’t be sure of your breath.

But it could also be more serious than that. Bad breath can be an indicator that something is seriously wrong with your health. But how can you tell the difference? Here’s a guide to some of the causes of bad breath, and how serious they might be.

Is Bad Breath a Health Warning?

Your Last Meal

Sometimes, we eat something that causes bad breath. Peppers, onions, garlic, curries, cheese, and seafood are all culprits in causing bad breath shortly after eating.

This is easy to identify–you can learn which foods cause bad breath and avoid eating them when you are concerned about your breath.

But if you can’t link your bad breath to specific meals, you should suspect other causes.

Your Diet

Sometimes, it’s not any individual meal you’re eating. It’s the combination of your diet as a whole. While it’s good to give up sugar, many people want to go further and eliminate most carbs from their diet. This drives the body to burn other sources of energy, such as fats and proteins. The byproduct of this is ketones, which have a sweet, fruity odor.

Building up too many ketones in the blood can be dangerous, but for most people on a low-carb diet, this isn’t a concern.

Oral Hygiene

Even if food isn’t naturally smelly, it can become smelly if it’s left in your mouth too long. If you’re not cleaning your mouth well enough, food residue can rot in your mouth, causing very bad breath. This is particularly common for people who don’t floss and have residue stuck between their teeth.

Talk to your dentist or hygienist about the best practices for oral hygiene and get regular professional cleanings.

Tonsil Stones

Your tonsils have a very important role. They’re supposed to trap bacteria and debris that would otherwise go into your lungs or stomach. Unfortunately, sometimes they accumulate too much, creating balls of bacterial residue called tonsil stones. These can smell very bad and contribute to bad breath.

You can tell you have tonsil stones if you can see the white deposits trapped in the crevices of your tonsils. Other times, you might notice them when they come out, “appearing” suddenly in your throat or mouth. They are usually white and can be soft and/or gritty.

Tonsil stones may be a warning sign that you have high levels of bacteria in your mouth and need to improve your oral hygiene or adjust your diet.

Dry Mouth

Our mouth is supposed to be full of saliva most of the time. Saliva helps our mouth stay healthy by killing bacteria and repairing our teeth (albeit very slowly). And it helps remove food debris. If you have a dry mouth, it’s easier for odors to build up because of food or bacteria.

Dry mouth can be caused by dehydration, medication, or aging. Once you’ve identified dry mouth, we can look for the cause and try to find a solution.


Bad breath can be a side effect of diabetes. Because the body might have a hard time processing sugars for energy, the body can try to break down more fats, which leads to the production of ketones. The smell is similar to eating a low-carb diet, but unlike a low carb diet, diabetes is likely to lead to a toxic buildup of ketones if not properly treated.

Gum Disease

Gum disease is an infection of the area between your teeth and gums. As the pockets of bacteria grow deeper, anaerobic bacteria flourish. These bacteria “breathe” sulphur instead of oxygen, and produce smelly byproducts. The odor is like rotten eggs or may even be corpselike.

You can also see other signs of gum disease, such as red, swollen gums. Bleeding gums, even receding gums.

Gum disease threatens your teeth, but can also lead to deadly consequences in the form of heart disease, dementia, or cancer.


Smoking or chewing tobacco is terrible for your health, but it’s also terrible for your breath. They dehydrate your mouth and cause residue that causes smells long after use.

If you use tobacco, it’s a good idea to quit, and not just for your breath, either. Tobacco use can lead to tooth loss as well as dental implant failure.

Kidney Disease

As we said before, bad breath can be a sign that things are really wrong in your body. It can mean, for example, that your kidneys are failing. Your kidneys are supposed to filter waste out of your blood, but if they aren’t working properly, it can build up. This can make your breath smell like ammonia, fish, or even urine.

If you or others notice this type of bad breath, it’s important to talk to a doctor right away.

Liver Disease

Your liver is also supposed to filter out toxins. And like the kidneys, when it’s not doing its job, the result can be a toxic buildup that you can smell. The type of breath related to liver disease is called fetor hepaticus, and it’s usually described as a musty smell. If you have this type of bad breath, you need to talk to a doctor.

Infected Tooth

An infected tooth is another place where anaerobic bacteria can build up. An infected tooth is such a good place for bacteria to collect that it can actually serve as the jumping-off point for other infections of the bone, sinuses, lungs, or brain.

An infected tooth needs to be treated with root canal therapy or extracted right away. Signs of an infected tooth include a tooth that becomes discoloured, sores on the gums, local warmth, and fever.

Trying to Find the Cause of Your Bad Breath?

If you experience regular bad breath, but aren’t sure of the cause, we can help you narrow it down. In most cases, we can treat the cause. You’ll enjoy not just fresher breath, but improved general and overall health.

Please call (02) 9686 7375 today for an appointment with a Sydney area dentist at My Hills Dentist in Baulkham Hills.