Rhinitis

I am a 231 days / 7 months 3 weeks old baby

Rhinitis (pronounced /raɪˈnaɪtɪs/), commonly known as a runny nose, is the medical term describing irritation and inflammation of some internal areas of the nose. The primary symptom of rhinitis is nasal dripping. It is caused by chronic or acute inflammation of the mucous membrane of the nose due to viruses, bacteria or irritants. The inflammation results in the generating of excessive amounts of mucus, commonly producing the aforementioned runny nose, as well as nasal congestion and post-nasal drip.[1]

Causes

Rhinitis is caused by an increase in histamine. This increase is most often caused by airborne allergens. These allergens may affect an individual's nose, throat, or eyes and cause an increase in fluid production within these areas.[2]

Allergic Rhinitis

Allergic rhinitis is an allergic response to outdoor or indoor allergens. Outdoor triggers of allergic rhinitis include ragweed, grass, tree pollen, and mold spores. Indoor triggers include dust mites, pet dander, or mold that grows in humid indoor places such as carpets. Outdoor allergens cause seasonal allergic rhinitis (also known as hayfever), that typically occurs during the spring and summer. Indoor allergens can cause pereniall (year-round) allergic rhinitis.[3]

-----
[1] Wikipedia
[2] ibid
[3] About.com