The nose is used for breathing but it has another important function as well and that is filtering the air that goes into your lungs. It filters out the dust particles, bacteria and other pollutants on a daily basis. This is collected by the fine hair in your nose called cilia and then along with nasal mucus, goes into the back of the throat. In the stomach the bacteria is destroyed by acid. This is a normal bodily function and most people do not even pay attention to it because the mucus is virtually unnoticeable.
Under normal circumstances this does not cause any problem. But if the mucus stays at the back of the throat, the anaerobic bacteria will do its work, breaking down the proteins present in the mucus and phlegm. Once the bacteria start this, they liberate the sulfuric compounds which are released along with the breath and cause bad breath. The post nasal drip thus transforms natural breath into foul breath.
Anaerobic bacteria flourish in phlegm and mucus because these substances offer them protection from external threats, and provide them with nourishment that they need. Milk, dairy products and foods that are rich in protein are also very attractive to these anaerobic bacteria.
When anaerobic bacteria get exposed to open air, they die. Mucus protects them from this situation by keeping them surrounded. This protection, together with the food that mucus provides, allows these bacteria to propagate and keep producing the bad odor we normally know as bad breath. If you have colds or some other illness that makes you produce more mucus, it naturally follows that you will be more prone to having bad breath.
Antihistamines and medications developed for the relief of postnasal drip dry up the sinuses and prevent mucous buildup. This is a good thing because now you can breathe out of both sides of you nose instead on only one or none. The antihistamines, however, may also cause dry mouth. Dry mouth is another source of bad breath because it mimics an anaerobic environment. The way to eliminate dry mouth if it is necessary to take antihistamines or other medications that have a drying effect, would be to remain hydrated throughout the day by drinking plenty of fluids, preferably water. Another way to maintain saliva production if you are experiencing dry mouth would be to chew gum.
If you have a particularly bad case of the colds and oral medications are not enough to get rid of mucus or postnasal drip, you can look at other options. For instances, you can take a warm shower while using a humidifier to keep the air around you damp. Adding a few herbs to your warm bath water can also be helpful. After your warm bath, you can try sipping hot soups with peppermint or other herbs that can help thin out your bothersome mucus. This is very useful especially in cold weather when it is extra difficult to cough out phlegm and mucus.
Relief may be found in a nasal sinus formula or a nasal sinus irrigator to flush the sinuses of oxygenating oral care products that minimize the amount of post-nasal drip you may be experiencing. Nasal sinus drops are intended to cleanse and alleviate excessive mucus accumulation, as are AktivOxigen tablets. These can be used as a mouthwash or a rinse to flood the back of the tongue and throat with oxygen. These products are effective at neutralizing the volatile sulfur compounds.
In conclusion, people who suffer with postnasal drip are more prone to bad breath and lousy tastes because the bacteria will start to extract sulfur compounds from the amino acids that make up these proteins. They love the amino acids, which are common to mucous and phlegm, and also in dairy foods. Remember every case of bad breath, is different and there is no such thing as one formula to treat every case of halitosis. Methods that work for one person may not work for another. If you find you are unable to control your postnasal drip, consult your doctor.