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Why does my breath smell bad, and what can I do about it?

Most of us can’t smell our own breath. If someone bravely informs you your breath smells, believe them, and do something about it. Or if you are worried you have bad breath, seek out a trusted opinion.

Your breath can be the first sign something in your body needs attention. Here are some tips to help you identify the cause, and how to fix it.

What causes bad breath?

Of the many causes of bad breath, 90% originate from putrid-smelling bacterial by-products inside our mouth. These by-products form a bouquet of odours that can make our breath smell like rotten eggs (volatile sulphur compounds) or poo (methyl mercaptan/hydrogen sulphide).

The largest and most significant odour-cultivating culprit is our tongue. The back of our tongue is a perfect petri dish for bacteria that feed on dead cells, saliva proteins, sinus ooze and fluids from untreated gum disease.

These bacteria can form a furry coat on our tongue that permeates our breath. The good news is you can fix this by brushing your tongue when you clean your teeth.

Toothbrushes in a holder
Brush your tongue as well as your teeth. Shutterstock

Eating onion and garlic can add a sulphurous tone to your breath for up to three days, due mainly to food particles left behind. Tobacco smoking also causes bad mouth smells to linger. Pus from dental infections can also be a smelly culprit.

Hard-to-reach places in the mouth where the toothbrush just can’t seem to clean can act like greenhouses where unhealthy bacteria thrive. Spaces in faulty or broken fillings, holes in teeth, gaps (pockets) in the gums that form with advancing gum (periodontal) disease, as well as improperly cleaned dental implants, dentures and braces, all contribute to bad odours.

Your dentist or hygienist can help identify these smell-promoting reservoirs, and fix or clean them. They can also help customise your oral hygiene routine to improve your health and reduce malodour.


Read more: Why do I grind my teeth and clench my jaw? And what can I do about it?


What about morning breath?

We all experience morning breath, with some suffering more than others. Morning breath occurs when our saliva flow slows or stops while we sleep. And without saliva to wash, dilute or flush, everything stagnates: food particles ferment and the bacteria multiply to release gassy odours.

This is why it is important to brush your teeth and gums, and use appropriate tools such as floss or interdental brushes before going to bed. If you are unsure, your dentist or hygienist will be able to identify which tools work best for you.

Other factors that reduce saliva include stress, anxiety, fasting, dehydration, antidepressants and blood-pressure-reducing medication, recreational drugs, caffeine and alcohol.

And if you tend to breathe through your mouth rather than your nose while asleep, your morning breath may be worse. Mouth-breathers can have sinus issues that block their noses to prevent proper breathing.

Garlic in a sieve
Eating onion and garlic can add a sulphurous tone to your breath for up to three days. anshu/unsplash, CC BY

More serious causes

Chronic (long-term) sinusitis and tonsillitis can also cause bad breath (especially if the tonsilitis causes tonsil stones – smelly cheese-like clumps of bacteria, dead skin cells, keratin and foreign debris).

Occasionally, young children may insert small objects into their nasal passages, which causes a buildup of bacteria and a yucky smell.


Read more: Is whitening bad for teeth? We asked five experts


What do I do if I have bad breath?

For most of us, good oral hygiene, drinking plenty of water, avoiding tobacco products, regular dental visits, and chronic sinus and tonsillitis management will help avoid bad breath.

In some instances, we may choose to suffer the short-term consequences (because onion and garlic are delicious). Chewing sugar-free gum or mints may temporarily ease any issues caused by last night’s garlic pizza.

If you’re concerned, see your hygienist or dentist, who can diagnose and help you manage the cause of your bad breath.

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