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Bad breath


Bad breath, also known as halitosis, is a common problem that can affect anyone of any age. Most people have short periods of bad breath at some point, and it is estimated that up to 50% of people have persistent bad breath.

What causes bad breath?

Bad breath can have several causes:

  • In most cases, bad breath is caused by bacteria in the mouth breaking down bits of food.
  • Persistent bad breath is often a sign of gum disease.
  • Eating strongly flavoured foods, such as onions and garlic, can cause your breath to smell unpleasant.
  • Smoking and drinking a lot of alcohol can also cause bad breath.
  • Occasionally, bad breath is the result of an infection or illness, or taking some kinds of medication.

See Bad breath - causes for more information.

Treating bad breath

Good oral hygiene is usually enough to prevent and treat bad breath. See Bad breath - treatment  for more information.

Your dentist can advise you on how to improve your oral health and can refer you for further investigation if they think there may be another cause for your bad breath.

How to find out if you have bad breath

It can be difficult to know if you have bad breath. Other people usually notice it first, and they may find it difficult to tell you. If you are worried that you have bad breath, you could ask a close friend or family member to tell you honestly whether they think you have.

A simple test you can do yourself is to lick the inside of your wrist and wait for the saliva to dry. If the area you licked smells unpleasant, it is likely that your breath does too.

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There are several causes of bad breath.

Poor oral hygiene

The most common cause of bad breath is poor oral hygiene.

Bacteria that coat your teeth, tongue and gums can cause plaque (the soft white deposit that forms on the surface of the teeth), gum disease and dental decay. These bacteria combine with saliva and food in the mouth, breaking down food particles and proteins. This releases an unpleasant-smelling gas. 

If you do not brush and floss your teeth regularly, any food that is trapped between your teeth will be broken down by the bacteria, causing bad breath.

These bacteria can also live in the rough surface of the tongue. Therefore, as well as brushing your teeth, cleaning your tongue can help control bad breath.

Persistent bad breath or a bad taste in your mouth can be warning sign of gum disease or tooth decay.

Any oral hygiene problems should be picked up and treated in regular check-ups with a dentist or hygienist.

Morning bad breath

Most people have bad breath when they wake up in the morning. This is normal and occurs because the mouth dries up overnight. This slows down the flow of saliva that normally washes away food particles. Bacteria quickly break down any bits of food left in the mouth, and an unpleasant, stale smell is released. The flow of saliva usually increases once you start eating.

Food and drink

Eating strongly flavoured foods, such as garlic, onions and spices, often cause your breath to smell. Strong-smelling drinks, such as alcohol and coffee, can also cause bad breath. This type of bad breath is usually temporary and can be easily avoided by not eating or drinking these types of food or drink. Good dental hygiene also helps.


Some medication can cause bad breath. Medicines that have been associated with bad breath include:

  • nitrates - sometimes used to treat angina
  • some chemotherapy drugs
  • phenothiazines (tranquilisers)

Talk to your GP about possible alternative medicines.


If you smoke, your breath is likely to smell of stale smoke. As well as making your breath smell, smoking also causes staining and loss of taste and irritates your gums. This increases your risk of gum disease, another cause of bad breath. Stopping smoking will lower this risk and help prevent bad breath.

Medical conditions

Bad breath can be caused by a medical condition, although this is rare.

Dry mouth (xerostomia) is a condition that affects the flow of saliva. This can cause bacteria to build up in the mouth, leading to bad breath. Dry mouth can be caused by salivary gland problems or continually breathing through the mouth instead of the nose. As you get older, you may produce less saliva, which can lead to bad breath.

Other medical conditions that can cause bad breath include:

  • infections in the lungs, throat or nose
  • bronchitis
  • sinusitis
  • diabetes
  • liver or kidney problems
  • gastritis (inflammation of the lining of the stomach) and food reflux

Crash dieting, fasting and low-carbohydrate diets, such as the Atkins diet, can also cause bad breath. These cause the body to break down fat, which produces chemicals called ketones that can be smelt on the breath.


Some people are convinced that they have bad breath when they do not. This psychological condition is known as halitophobia.

People with halitophobia are paranoid about the smell of their breath and often misinterpret other people's actions and comments, thinking that they are suggesting they have bad breath. They become fixated with cleaning their teeth, chewing gum and using mouth fresheners.

Treatment for halitophobia involves talking therapies and cognitive behavioural therapy to help the person overcome their paranoia and fixation on the smell of their breath.

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Treatment for bad breath depends on what is causing it.

The simplest and most effective treatment is usually improving your dental hygiene. To avoid bad breath, keep your mouth and teeth clean:

  • regularly brush your teeth and gums
  • floss in between your teeth
  • keep your tongue clean

Keeping your teeth and mouth healthy

Your dentist is likely to recommend that you brush your teeth at least twice a day using toothpaste containing fluoride.

  • Choose a small to medium sized toothbrush with soft, multi-tufted synthetic bristles. 
  • Replace your toothbrush every 3-4 months.
  • Brush your teeth for a minimum of two minutes each time. 
  • Brush all areas of your teeth, and particularly where the teeth meet the gums.
  • Your dentist or hygienist may recommend a special single-tufted brush for specific problem areas of your mouth.
  • Use a separate toothbrush, or tongue scraper, to lightly brush your tongue (some toothbrushes have a ‘tongue cleaner’ on the reverse of the brush head).
  • Use dental floss to clean between your teeth and remove any trapped food that could cause tooth decay.
  • Your dentist may suggest daily rinsing with an anti-bacterial or anti-odour mouthwash (this should not replace brushing, but can be included in your daily routine).
  • Avoid brushing your teeth for 30 minutes after drinking an acidic drink, such as fruit juice, or eating acidic fruit, such as oranges, to help prevent tooth erosion.

How can your dentist help?

Your dentist can recommend the best way to clean your teeth and gums and show you any areas you might be missing. Regular check-ups with your dentist will make sure any plaque is removed from your teeth, especially in hard-to-reach areas. It will also ensure any signs of gum disease are noted and treated early on.

Wearing dentures

If you wear dentures, take them out at night to give your mouth a chance to rest and clean them twice a day:

  • Do not clean dentures with toothpaste, which can scratch the surface and cause stains to build up.
  • Clean them thoroughly with soap and lukewarm water, a denture cream or a denture-cleaning tablet.
  • Use a separate toothbrush to clean your dentures.

This routine should make sure your dentures stay fresh and clean and avoid the build-up of plaque, which could cause bad breath.

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