Disorders in the mouth (oral)

Bacteria on the back of the tongue

Unpleasant-smelling tongue scrapings

Healthy gums and teeth

A doctor’s or dentist's examination

Periodontal disorders, such as gingivitis and periodontitis 

Affected gums and teeth noted during the examination

In people with a history of poor oral hygiene

A dentist’s examination

Cancers of the mouth (most are identified during a doctor's or dentist's examination long before they cause bad odors)

Usually identified during the examination

More common among older adults, who often have an extensive history of using alcohol and/or tobacco

Biopsy, CT, or MRI

Disorders outside the mouth (extraoral)

A foreign object (body) in the nose†

Often a pus-filled or bloody discharge from the nose

Seen during the examination

Usually in children

A doctor's examination

Sometimes imaging

Cancer of the nasal passages and upper throat†

Discomfort when swallowing

A doctor's examination

Lung infections, such as a lung abscess, bronchiectasis, or an infection caused by an inhaled foreign object

Cough that produces blood or sputum (phlegm)

Fevers

Chest x-ray

Cultures of sputum

Sometimes CT or bronchoscopy

Imagined halitosis (psychogenic halitosis)

Unpleasant smell not detected by others

Often in people known to exaggerate other normal body sensations

A doctor's examination

Sometimes a consultation with a psychologist

Sinus infection†

A pus-filled discharge from the nose

Face pain, headache, or both

A doctor's examination

Sometimes CT

Zenker diverticulum

Gastroesophageal reflux (GERD) disease

Spitting up of undigested food (regurgitation) when lying down or bending over

Video of the upper digestive tract after barium is given by mouth (barium swallow)

Swallowed or inhaled substances

Alcoholic beverages, garlic, onions, tobacco

Apparent based on the person's history

Diagnosed after the doctor's examination rules out other causes

A doctor's examination

Avoidance of the substance to see if symptoms go away