What causes bad breath even after brushing?

It is quite common for people to experience bad breath in their life. It can be frustrating to have a bad odor on your breath which doesn’t improve with brushing, flossing and the use of mouthwash. This is especially unfortunate for patients who have breath that smells like feces. While there can be benign causes for breath which smells similar to poop, in most cases, the issues causing this phenomenon are quite serious and require medical intervention.

Potential Causes

There are a variety of different issues which can cause the breath to smell like poop. These issues can range from things such as poor oral hygiene to liver failure.

Poor Oral Hygiene

Poor oral hygiene can result in breath that smells like poop. Neglecting to brush the teeth twice daily and floss regularly can make the breath smell as plaque and bacteria easily accumulates on and around the teeth. Food which is not removed through flossing remains on the teeth which causes the breath to have a foul odor.

Bad smelling breath can also be contributed to gum disease, which is caused by a patient neglecting their oral hygiene. When a patient neglects their oral health, it leads to overgrowth of bad bacteria found in the mouth. This bacteria then causes a foul odor on your breath. Dentures and dental appliances which are not properly cleaned can also cause severe halitosis or bad breath.

Obstructed Bowel

Obstructions in the intestinal track are dangerous medical emergencies. These obstructions can occur when there is a blockage formed in the large or small intestine.

A blockage of the intestinal tract can cause breath which smells like feces. This occurs not only due to the feces which are trapped inside the intestines, but also because food which has been consumed is unable to move through the intestinal tract. Anything which is consumed while you are unable to pass a bowel movement will remain inside the digestive tract and ferment. This process ultimately causes bad breath.

In addition to the bad breath odor, patients who have an intestinal obstruction may experience the following symptoms:

  • Reduced appetite
  • Bloating
  • Abdominal cramps, swelling and pain
  • Constipation
  • Nausea
  • Vomiting
  • Diarrhea
  • Unable to pass gas


Prolonged vomiting, and the dehydration that ensues, can also result in bad breath from a dry mouth. Saliva cleanses the mouth and helps to eliminate odor. In cases of dehydration, patients do not produce enough saliva. Vomiting as the result of an obstructed bowel can also cause the breath to smell like feces.

Sinus Infections

Another health issue which can cause the breath to smell like feces is a sinus or respiratory infection. These infections can be from bronchitis, viral colds, strep throat and other issues. When the bacteria moves from the nose into the throat, it can cause an incredibly unpleasant odor. Additional symptoms of a sinus infection can include the following:

  • Thick, yellow or green nasal drainage
  • Cold lasting more than 10–14 days
  • Low-grade fever
  • Headache
  • Fatigue and irritability
  • Postnasal drip which presents itself as nausea, vomiting, cough, or a sore throat
  • Swollen eyes

It is more common for children to develop a sinus infection following a viral cold than adults, however similar symptoms can be present in both.

More on Halitosis : What does Halitosis Smell Like?

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