7 Types of Bad Breath and What They Mean

October 15th, 2019

types of bad breath


Throughout the United States, there are over 50 million people suffering from halitosis, or various types of bad breath. Many do not seek medical or dental assistance though, not least due to the social stigma linked to bad breath.

Foul-smelling breath isn’t all about poor dental hygiene. It’s often about much, much more than that. Here, we talk through some of the primary kinds of bad breath – what they mean from a more serious clinical perspective.

Many studies show that as many as 1-in-10 causes of bad breath are a consequence of causes outside the oral cavity. Bad breath can be a product of liver disease, kidney disease, upper respiratory tract infections and asthma, to name a few.

As part of your NAPLEX test, or other clinical pharmacy examination, you should have a thorough knowledge of these diagnostic indicators.

Whilst you may not be required to issue a formal diagnosis, knowing the patient’s history, in tandem with what odors are linked to specific disease states, can add tremendous practical and clinical detail to your armoury.

Let’s get started.

Types of Bad Breath

Below, we’ve tabulated many of the primary odors, their associated disease states, as well as other key clinical detail you are expected to know.

Odor Indication Comments
Acidic Asthma

Cystic fibrosis

Acidic breath increases during acute attacks.

Lung cancer is often described as “ammonia” or “musty”-like.

Fishy Kidney disease


In chronic kidney failure, urea levels can rise in saliva, giving rise to a fishy or ammonia-like odor.

Trimethylaminuria is caused by an inability of the body to break down choline, leading to an build-up of trimethylamine.

Cheesy Halitosis of nasal origin Combination of bacteria, food, and other secretions.
Fruity Diabetes type 2 Low carb diets and result in fat breakdown, leading to ketone accumulation and a fruity smell.
Ammonia Kidney disease See “fishy” above.
Sweet, musty Liver cirrhosis In liver disease, the body accumulates dimethyl sulphide. The body tries to remove sulfur-based compounds from amino acid degradation.
Fecal Bowel obstruction Obstruction can cause fetalodor to reverse back through the GI tract into oral cavity.


We often don’t think about breath as a diagnostic indicator. Yet, it remains a very powerful tool in the diagnostic process.

As we have learned, disease states have a direct impact on what compounds are produced, as well as how many of these compounds interact with saliva. Identifying halitosis is often just the start of the problem, as many of these disease states are long-term.

Halitosis can remain, at least for the duration of the disease.

NAPLEX Study Guide is the leading online platform to help you pass your NAPLEX exam, or other clinical pharmacy examinations. Check back to our blog soon for more great diagnostic tips to strengthen your knowledge in the months ahead.


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