common causes of bad breath

11 common causes of bad breath

Diseases, Gastroenterology

Halitosis, better known as bad breath, is a common but unusual condition. Often the person who has it does not realize it, and others, who know of the problem, are unlikely to tell the person affected. Think of the gums, lozenges, and mouthwashes that promise to fight bad breath, and the extent of the problem is obvious.

Some people who know they have bad breath will do almost anything to cure it. Untreated, it can be a deal-breaker for relationships, could stop an otherwise good employee from being promoted, or a salesman from making sales. In our post today, we discuss 11 common causes of bad breath. Our next post is about prevention and treatment.

Common causes of bad breath

Poor oral hygiene

The most common cause of bad breath. Food left on the tooth surfaces, between teeth, on gums, the tongue, or dental appliances will grow bacteria that produce unpleasant gases. If you have gingivitis—chronic gum infection—or dental cavities, the problem will be even worse.

Food and drink

After digestion of strong-smelling foods like onions, garlic, and many spices, the breakdown products are carried to the lungs which you exhale around you. Coffee and alcohol are also common causes of temporary bad breath. Brushing your teeth will not help much.

Certain diets

Very low carbohydrate, fasting, or crash diets can push your body to break down fat to get energy, which produces foul-smelling ketones that you exhale. A high protein diet, especially animal proteins, can contribute to ketone breath as well.


Some medications such as nitrates, chemotherapy, certain tranquilizers, large doses of vitamin or herbal supplements can have this side effect.  Especially any medication (such as anticholinergics) that decreases your saliva and dries your mouth can cause bad breath.

Mouth breathing

If your nose is obstructed due to allergies or some anatomic obstruction, you will breathe through your mouth and quickly dry your saliva. Saliva is nature’s oral lubricant that helps wash away food particles and bacteria, and neutralizes oral acids.


Maybe it’s hot or you have been exercising or just haven’t taken in enough water. Your salivary flow will slow and thus your natural cleaning fluid is depleted.

Refux or stomach problems

This is a common cause that many people never think of. Stomach acids coming up into your esophagus smell bad. If you are infected with the H. pylori bacteria—which causes a majority of stomach and duodenal ulcers—the bacteria produce gases that travel up to your mouth.

Medical conditions

Chronic sinus infections with post-nasal drip, chronic tonsil or lung infections, uncontrolled diabetes, certain liver or kidney conditions, metabolic disorders, and even some cancers can produce bad smelling chemicals that are exhaled.


This habit works in at least three ways to make your breath bad. It dries your mouth, damages your teeth and gums, and the product itself produces bad smelling gases.

Morning breath

A person who breathes through their mouth at night or snores badly (often due to obesity) develops a dry mouth and typically has bad breath when they wake up. Only after they drink clear fluids such as water does it improve.


It is believed that up to 1% of people have this condition. Halitophobia is when you believe you have bad breath but do not. Even after confirmed by a dentist and friends that there is no problem, some people become so obsessed with this that they avoid approaching others. It can be a serious (non) condition.

Note that bad breath may be several of these issues acting together. In our next post we discuss ways to cure the problem.

To find a doctor, of any specialty, anywhere in Brazil, check out our website:

See also in ProcuraMed:

What is your microbiome, and why it is your friend

How to improve your internal microbiome

Esta postagem também está disponível em: Portuguese (Brazil)

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