It’s hard to diagnose it yourself. Breathing into your hands and sniffing them only tells you if your hands smell. Licking the back of your wrist and smelling it after 10 seconds isn’t accurate either. Flossing and then smelling is only likely to reflect any decaying food. The taste in your mouth isn’t closely related to how your breath smells. Breath clinics have machines such as halimeters that measure sulphur emissions, but the most reliable way is for an expert to smell and score the level and type of odour. Or failing that, a close friend.
In 85% of people, halitosis originates in the mouth. You may think that’s obvious, but tonsillitis, acid reflux in the oesphagus and kidney and liver problems can also make the breath smell. However, it’s the 600-plus bacteria in the mouth – particularly the ones producing unstable sulphur compounds from proteins breaking down – that are usually the culprits.
A BMJ review says that it is poor oral hygiene that’s usually to blame. The most likely cause is food and bacterial plaque on the tongue and teeth – especially when this causes gum inflammation. The main culprit is the back of the tongue, and some people happen to have grooves that allow a white coating to accumulate. A coating that is only 0.1mm thick can reduce the oxygen to the tongue, allowing the bacteria that grow best without oxygen to flourish and produce smelly compounds.
Regular teeth-brushing and flossing will reduce the problem. A systematic review found that tongue scraping (which I always thought was a stupid idea) might work – but do it gently, back to front, as there are more bacteria at the back. Another review found that mouthwashes with chlorhexidine gluconate, which reduce bacterial levels, can help, especially after tongue-brushing when the bacteria are exposed and defenceless (although too much mouthwash can stain the teeth). Using before bedtime may also work well, as bacteria multiply at night when the mouth is dry and gets less oxygen. Ones without alcohol are best as they avoid drying out the mouth.
But all these things need to be used continually. Chewing sugar-free gum stimulates saliva and reduces bad breath and is a good insurance policy during the day.