CBS.com; CBS All Access; CBS News; CBSN; Watching Live TV. All Access Live TV; TV Provider
Thick blood may also be caused by the presence of harmful pathogens such as fungi, viruses, bacteria, and parasites. These pathogens can actually activate a coagulation response in the body as a way to avoid being attacked by the bodyâs immune system.
Chemotherapy also causes the immune system to overreact and excessive phlegm is often the result. Food allergies are known to cause excessive phlegm and certain types of food such as dairy products cause a thickening of mucous. Postnasal drip also commonly causes excess mucus at the back of your nose and throat many times after eating.