鼻炎（rhinitis），是一个医学术语，用于描述鼻腔中的一些区域受到刺激而产生之炎症。鼻炎典型的病征通常表现为流鼻涕。鼻炎是由于急性或慢性的鼻粘膜如病毒、病菌感染，或刺激物的作用下受损而导致的。鼻炎会导致产生过多粘液，通常会引起流鼻涕、鼻塞等症状。鼻炎不单只是影响鼻子，同时还会影响咽喉和眼睛。它还会影响人的睡眠品质、听力以及学习能力。鼻炎的症状是由过高的组织胺导致的。而导致组织胺增高的最常见原因是空气中传播的过敏原，这些过敏原会感染鼻子、咽喉、眼睛，并使得这些部位产生液体分泌物。

通过美国最近的研究表明，五千万以上的美国人仍是鼻炎患者，相当于美国人口的六分之一。通常儿童在3－13岁之间最容易得鼻炎。

Rhinitis or coryza is irritation and inflammation of the mucous membrane inside the nose. Common symptoms are a stuffy nose, runny nose, sneezing, and post-nasal drip.

In rhinitis, the inflammation of the mucous membrane is caused by viruses, bacteria, irritants or allergens. The most common kind of rhinitis is allergic rhinitis, which is usually triggered by airborne allergens such as pollen and dander. Allergic rhinitis may cause additional symptoms, such as sneezing and nasal itching, coughing, headache, fatigue, malaise, and cognitive impairment. The allergens may also affect the eyes, causing watery, reddened, or itchy eyes and puffiness around the eyes. The inflammation results in the generation of large amounts of mucus, commonly producing a runny nose, as well as a stuffy nose and post-nasal drip. In the case of allergic rhinitis, the inflammation is caused by the degranulation of mast cells in the nose. When mast cells degranulate, they release histamine and other chemicals, starting an inflammatory process that can cause symptoms outside the nose, such as fatigue and malaise. In the case of infectious rhinitis, it may occasionally lead to pneumonia, either viral pneumonia or bacterial pneumonia. Sneezing also occurs in infectious rhinitis to expel bacteria and viruses from the respiratory system.