causes - dry air, smoking, disease, allergens, infection, PND serious vs not sleep
REFERENCES & RESOURCES
- http://umm.edu/health/medical/altmed/condition/cough
- http://umm.edu/health/medical/altmed/condition/pharyngitis
- http://www.health.harvard.edu/staying-healthy/that-nagging-cough
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205006/
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2802352/
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4223129/
- http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2862067/
- https://nccih.nih.gov/health/flu/ataglance.htm