Causes of Bad Breath: Post Nasal Drip

Post-nasal drip can keep you up at night. It can interfere with your ability to speak and swallow. It can interfere with your ability to enjoy sexual intercourse. And it can give you bad breath.

Effective treatment of post-nasal drip can make your whole life better. But getting rid of post-nasal drip is not always an easy process. In the nineteenth century—a period of American history when most Americans smelled bad—post-nasal drip was so common that both American and British physicians wrote papers about “American catarrh.” The relative abundance of pollens in North America, in some places all year around, caused nearly all Americans to have post-nasal drip and to have it all year round, resulting in horrible bad breath. But why should such a simple ailment cause such terrible breath.

What Causes Post-Nasal Drip? And Why Does It Cause Bad Breath?

Before explaining the causes of post-nasal drip and why it causes bad breath, let’s go over some basic human anatomy. There are pockets of open space in your skull known as sinus cavities. They are behind your nose, beneath your eyes, and between your cheeks.

Nobody really knows what the sinuses do. Some experts say that they decrease the weight of the skull and reduce stress on the brain stem. Others claim that the sinuses act as a cushion to protect the brain and spinal column. Whatever sinuses really do, any time you are aware of your sinuses, it is not a pleasant experience.

When we say that our “sinuses” are acting up, we are really referring to the nasal cavity below the nose. This structure strains dust and other particles from the air before it goes to the lungs. The openings to the sinus can get clogged by excessive mucus, which can slowly drip down the back of the throat.

Post-nasal drip is more than just a stuffy nose. When the immune system detects bacteria, it usually tries to destroy them with inflammation. The result is the stuffed-up feeling we all know well.

But post-nasal drip can also be caused by allergies. Chronic post-nasal drip is often caused by food allergies. If you have chronic post-nasal drip and there is a food you eat absolutely every day, it is the most likely culprit. But it is also possible for post-nasal drip to be caused by infection and allergies at the same time.

Why does post-nasal drip cause bad breath? Mucus is made up of proteins. Bacteria consume these proteins but don’t use all of the amino acids in the protein, especially cysteine, cystine, and methionine. These amino acids are rich in sulfur. Enzymes in the lining of the throat and enzymes secreted by bacteria can transform these amino acids in hydrogen sulfide, the odor we associate with rotten eggs, and methyl mercaptan, the odor we associate with sewer gas. In turn, these chemicals themselves can loosen healthy cells from the lining of the throat, cutting them off from oxygen and nutrients, and creating more food for bad breath bacteria.

What Can You About Post-Nasal Drip?

Getting rid of post-nasal drip often gets rid of bad breath. But how do you get rid of post-nasal drip?

Let’s skip any discussion of treatments that don’t work very well and get right to the things you can do that really will stop post-nasal drip.

  • Allergen avoidance. If there is a substance in your diet or your environment that causes a constant allergic reaction, avoiding it will stop post-nasal drip and clear up bad breath. It is no longer necessary to endure scratch testing to identify your allergies; there are also blood tests that tell you which foods or substances you are allergic to. If you can’t afford allergy testing, then try (1) careful cleaning of your home and office and (2) trying totally different and new foods for at least 3 days—nothing you ordinarily eat. If cleaning drapes or mattress covers or carpets stops your post-nasal drip, you know how to prevent it in the future. If eliminating all your regular foods stops your post-nasal drip, you know it is some common food that causes your allergies. It’s usually something you eat every day or even every meal. Eliminating that food will get rid of both post-nasal drip and bad breath.
  • Antihistamines, steroids, and decongestants stop nasal drip, but because they also dry out the mouth, they often make bad breath worse. Overuse of decongestants can result in rhinitis medicamentosa, in which the medications for post-nasal drip perpetuate post-nasal drip.
  • Treating non-allergic rhinitis. Constant exposure to caustic odors or tobacco smoke can cause constant post-nasal drip. Remove the caustic odors or the tobacco smoke, and post-nasal drip and bad breath go away with them.
    Treating senile rhinitis. After the age of 55, some people get runny nose that doesn’t seem to have anything to do with infections or allergies. It’s caused by the same cardiovascular reactions that cause some people to get headaches after having sex. Dealing with this kind of post-nasal drip involves dealing with recurring strong emotions, avoiding changes in position that cause blood to rush to the head (or seeing the doctor about changing blood pressure medications that cause blood to stay in the lower body), and dealing with changes in air pressure caused by frequent flying or working in labs with negative air pressure to keep chemicals or biological agents inside.
  • Treating gustatory rhinitis. If you have gustatory rhinitis, it may not be onions or garlic that give you bad breath. It may be peppers or curry. Certain kinds of spicy foods activate the vagus nerve, increasing tear production and salivation. In some people, the reaction does not shut off when the meal is over. Some people can get post-nasal drip from eating spicy foods, and eating spicy foods every day will indirectly cause bad breath. The only treatment, short of having a surgeon install a pacemaker to the nerve (there are a few people who have had this procedure), is to avoid the spicy foods that cause post-nasal drip.


Click here to learn how to cure bad breath in 3 days