People back away from you whenever you talk to them. Or someone has told you frankly that you have bad breath. The most obvious and immediate cause is eating a dish laced with peperoni, onions, garlic or blue cheese. But there are plenty of other possible causes.

Perhaps you’re a smoker; or could it be that you don’t brush your teeth or floss often enough? Gum disease is another common cause of bad breath. If you have an abscessed tooth or a sinus infection, your unpleasant breath is almost certainly a side-effect.

Other suspects include certain prescription drugs, a chronically dry mouth or too many cups of coffee.

It’s a common misconception that minty mouthwashes or breath mints will make your breath fresh. However, most mouthwashes contain alcohol, which dries up saliva. When you use them, you actually make your breath worse afterwards. And mint sweets are just a cover-up; they actually feed the odour-producing bacteria with more sugar.

Just how bad is your breath? To find out, perform a "sniff test" on dental floss after you have pulled it gently between your teeth—but make sure you choose only an unwaxed and unflavoured variety.

Another alternative is rubbing a flannel across the tongue and smelling it. If you are worried about your breath, talk to your dentist or hygienist.

They will also be able to advise you on mouth hygiene and will check to see whether gum disease or poor mouth hygiene are likely causes.

A dry mouth is a haven for the bacteria that cause bad breath. So find a tap and swish the water around in your mouth. Water will temporarily dislodge bacteria and make your breath a bit more acceptable.

At the end of your business lunch or romantic dinner, munch the sprig of parsley that’s left on your plate. Parsley is rich in chlorophyll, a well-known breath deodoriser with germ-fighting properties.

If you can get hold of an orange, peel and eat it. The citric acid it contains will stimulate your salivary glands and encourage the flow of breath-freshening saliva.

If there are no oranges in sight, eat whatever is available, except known breath-pollutants such as garlic, onions or stinky cheese. Eating encourages the flow of saliva, which helps to remove the unpleasant, odour-causing material on the surface of your tongue.

Vigorously scrape your tongue over your teeth. Your tongue can become coated with bacteria that ferment proteins, producing gases that smell bad. Scraping your tongue can dislodge these bacteria so you can rinse them away.

If you have a metal or plastic spoon to hand, you can use it as an effective tongue scraper. To scrape safely, place the spoon on the back of your tongue and drag it forwards. Repeat four or five times. Scrape the sides of the tongue as well, with the same back-to-front motion. But don’t push the spoon too far back in your mouth as you may activate your gag reflex and cause yourself to vomit.

Cloves are rich in eugenol, a potent antibacterial. Simply pop one into your mouth and dent it with your teeth. The pungent aromatic oil may burn slightly, so keep the spicy clove moving. Continue to bite until the essence permeates your mouth, then spit it out. Don’t use clove oil or powdered cloves; they are too strong and can cause burns.

Chew on fennel, dill, cardamom or anise seeds. Anise, which tastes like liquorice, can kill the bacteria that grow on the tongue. The others will help to mask the odour of halitosis.

Suck on a stick of cinnamon. Like cloves, cinnamon is effective as a mouth antiseptic.

Most popular branded products advertised as breath-fresheners are rarely, if ever, effective in the long term. But it appears that a chlorine dioxide rinse can combat the sulphur compounds responsible for bad breath.

Use a toothpaste that contains tea tree oil, a natural disinfectant. If you can’t find it in the pharmacy, look for it in health-food shops.

Use an oral irrigator, is a handheld gadget that rapidly pulses a small jet of water into your mouth, to flush out the bad bacteria. It can go deeper than a brush or floss can reach.

Carry a toothbrush with you and brush after every meal. Brushing thwarts the development of plaque, the soft sticky film that coats the teeth and gums. It is not necessarily good advice to brush immediately after a meal: if you have consumed anything potentially erosive, like cola or citrus fruit, this can cause added damage to dental enamel. In this instance, brushing an hour after a meal is better.

Keep chewing gum in your pocket or bag. Chewing a stick of gum, especially after meals, will stimulate saliva flow and clear away food debris.

To keep your toothbrush free of bacteria, store it, head down, in a lidded plastic tumbler of hydrogen peroxide. Rinse the brush well before you use it.

If you wear dentures, it’s possible that they are absorbing the bad odours in your mouth. Always soak them overnight in an antiseptic solution, unless your dentist has advised you otherwise.

Don’t skip meals. When you don’t eat for a long period of time, your mouth can get very dry. It becomes a perfect breeding ground for bacteria.

Some things can sour your breath even when there are no bad bacteria. These include cigarettes, alcohol, onions, garlic and especially strong cheeses such as Camembert, Roquefort and other blue cheeses. In situations where sweet breath is a must, use the commonsense approach—just say no.

Ask your doctor if a medication could be fouling the air you expel. Any drug that dries out your mouth, thereby depriving it of saliva, is suspect. These include over-the-counter antihistamines, decongestants, diet pills and also prescription medications for depression, rheumatoid arthritis and high blood pressure.

While all of us have bad breath from time to time, good oral hygiene should keep it to a minimum. But bad breath that lingers for more than 24 hours can also be a sign of gum disease, intestinal problems or a more serious condition.

If you brush and floss diligently, but can’t banish bad breath on your own, see your doctor or dentist. You should also see a doctor if your breath smells sweet or fruity, as this could be a sign of diabetes.