what causes a really thick stringy mucus
These conditions as well as other possible causes include: 1. Crohnâs disease. Crohnâs disease is an inflammatory bowel disease that affects your GI tract. Early symptoms may include diarrhea or fatigue. 2. Cystic fibrosis. Cystic fibrosis is a genetic disorder that results in thick, sticky mucus. This mucus often builds up in your lung, pancreas, liver, or intestines. 3. Ulcerative colitis. Like Crohnâs disease, ulcerative colitis is an inflammatory bowel disease. Itâs a chronic, or long-term, condition that causes inflammation in your large intestine or rectum. 4.