Good question

In most cases, bad breath comes from the mouth itself. Bacteria in the coating on the tongue, especially at the back, break down food debris and dead cells and produce volatile sulphur compounds, which smell. Gum problems, dry mouth and certain foods can also play a part.

Many people think so, but it is rarely the case. The oesophagus is normally closed, so odour from the stomach doesn’t escape when you breathe out normally. The source is far more often in the mouth.

Brushing is the foundation, but it is made for your teeth. The tongue has a rough surface where coating settles between the papillae, and the back of it is hard to reach with a brush. Cleaning your tongue with a toothbrush is a bit like cleaning windows with a washing-up brush, a tongue cleaner is shaped for the job.

No. Tongue cleaning comes from the Indian Ayurvedic tradition and is still a daily habit for millions of people in Asia. What’s new is that more people in the Western world have discovered it. Read the story.

They can give a fresh taste, but the effect is short-lived because they mask the odour rather than remove the coating. Feel free to use them as a supplement, but not as a replacement for cleaning your tongue.

For the best result: twice a day, morning and evening, right after brushing your teeth. See the instructions.

It shouldn’t hurt. Use light pressure, stick your tongue well out and start a little further forward. Breathe out slowly while you draw the tongue cleaner forwards. Most people get used to it quickly.

Rinse it under running water after each stroke and after use. Now and then, wash it with a little soap and warm water, and let it dry upright. According to the manufacturer, the plastic doesn’t absorb water.

Replace your tongue cleaner after 2–3 months of use, just like a toothbrush, so the cleaning edge always works at its best.

Yes, but young children should only use a tongue cleaner under adult supervision.

Persistent bad breath can have other causes, such as gum disease, cavities, dry mouth, tonsils or sinuses. Talk to your dentist or doctor.

OraSweet can be bought in a Danish web shop from DKK 25 each, with a volume discount when you buy more. You can have it delivered or pick it up free of charge at Astanga Yoga Studio in Copenhagen N. The shop is in Danish.