Bad Morning Breath – Causes and How to Prevent It

Bad breath in the morning is not unusual and can vary from a stale odor to a slightly offensive breath. However in some cases the odor may be so offensive that the breath may resemble the smell of feces, flatus, fish or even rotting or decaying organic matter (similar to a garbage can or dead animal). Despite good oral hygiene before bedtime and a clean bill of health from a dentist, bad morning breath may persist.


A person with chronic bad breath (halitosis) is more likely to have an offensive morning breath. However, bad morning breath can exist almost exclusively with no indication of halitosis otherwise. The cause of bad breath may vary from poor oral hygiene to problems in the mouth, airways, lungs and even the gut. Halitosis must always be investigated by a medical professional and the underlying disease should be treated, if present.

Reason for Morning Breath

With good dental hygiene at night, morning breath has an odor that is between stale and mildly unpleasant. It is often referred to as ‘puppy breath’ or ‘kitty breath’. Sometimes the mouth odor can be offensive. The odor of the common morning breath is due to a combination of factors that affects almost every person irrespective of any underlying disease.

Mouth Bacteria

There are many different species of bacteria that can be found within the mouth. The bacteria thrive within the mouth and releases various gases as a byproduct. This can be a factor in bad breath, irrespective of the time of the day.

Food Particles

Without proper dental hygiene, food particles will remain within the mouth. These food remnants may be broken down by bacteria and decompose rapidly. It is one of the common reasons for morning breath, which is usually a slightly offensive.

Dry Mouth

Saliva production reduces at night while asleep. Since saliva has antibacterial properties, the bacteria can thrive within the mouth while sleeping. This can further contribute to morning breath. It may be worse if there is some problem causing mouth dryness.

Causes of Bad Breath in the Morning

Bad breath in the morning may be due to similar causes as that of halitosis. If good oral hygiene is practiced before sleep yet an offensive or putrid odor is present upon waking, then further medical investigation is warranted. The bad morning breath in these cases can be a symptom of some underlying disease.

Oral Hygiene

Poor oral hygiene is one of the more common causes of bad morning. WIth saliva production being lower during sleep, bacteria can thrive within the mouth. Food particles that remain in the mouth may be consumed by the bacteria and food decomposes within the mouth. Therefore proper oral hygiene (brushing, flossing and a mouth wash) is important before bedtime.

Mouth Breathing

Mouth breathing for any reason may worsen  the breath at night. The oral cavity becomes drier than it normally would during sleep among mouth breathers. Any cause of nasal congestion typically leads to mouth breathing, especially while asleep.

Acid Reflux

A common but often ignored cause of bad morning breath is gastroesophageal reflux disease (GERD). The rising stomach acid with partially digested food can reach the throat and even the mouth. GERD or acid reflux tends to worsen during the night partly due to the increased stomach acid production at this time and lying flat. A morning sore throat may also be present in cases where the reflux worsens at night.

Diseases That May Cause Bad Morning Breath

  • Gum and tooth diseases including gingivitis, dental cavities and dental abscesses. Bad morning breath may at times be the only symptom of these diseases.
  • Infections (bacteria or fungal like oral thrush) or abscess formation in the nose, nasal sinus, throat, tonsils, lungs or esophagus are another common cause. Tonsillitis is a common cause of bad morning breath particularly when it arises with a bacterial infection.
  • Tumors of the nose, throat, mouth, lungs or esophagus may contribute to bad breath, particularly if there is an infection of the tumor.
  • Digestive conditions including gastroesophageal reflux disease (GERD), H.pylori infection of the stomach, small intestinal bacterial overgrowth (SIBO), Zencker’s diverticulum, gastroparesis and extreme dieting especially with ‘starvation diets’.
  • Diabetes mellitus can also contribute to bad morning breath when the body starts breaking down fats. The breath may have a ‘fruity odor’.
  • Certain prescription medication can cause bad morning breath. This is more likely to happen with drugs that reduce saliva product and particularly with medication that is taken in the evening.
  • Excessive alcohol consumption can worsen morning breath. It increases acid reflux and the breakdown products of alcohol present in the breath may combine with other odors in the mouth.

How to Prevent Bad Morning Breath

Any disease that causes bad morning breath needs to be investigated, treated and properly managed. The bad morning breath is just a symptom and it can ease by treating the underlying cause. However, a few simple measures can help to minimize bad morning breath.

  • Brush before bedtime. It is imperative to remove the food particles and to clean the mouth thoroughly by brushing with a fluoride toothpaste, flossing and rinsing with a mouth wash. Nighttime dental hygiene should be as thorough as the morning routine.
  • Keep a water bottle near the bed. Sip on water if there is severe mouth dryness whenever sleep breaks. However, do not drink too much water as it can disturb sleep to urinate.
  • Avoid late night snacks and try not to eat at least 2 hours before bedtime. This is more relevant for people with acid reflux as eating late can worsen the reflux.
  • Assess late evening or night meals. Stay away from foods with strong smelling ingredients like high sulfur foods. Garlic, onions and boiled eggs are come of the foods with a high sulfur content.
  • Do not drink alcoholic beverages before bedtime. Alcohol can weaken the LES (lower esophageal sphincter) and worsen acid reflux.
  • Use an antacid before bedtime if acid reflux is a common problem during sleep. It is always advisable to consult with a medical professional for chronic reflux as prescription drugs may be necessary.

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