Cold temperature<unk>  is especially common during winter months and certain low temperature seasons. Cold-induced<unk>  occurs due to a combination of thermodynamics and the body's natural reactions to cold weather stimuli. One of the purposes of nasal mucus is to warm inhaled air to body temperature as it enters the body. In order for this to happen, the nasal cavities must be constantly coated with liquid mucus. During cold, dry seasons, the mucus lining nasal passages tends to dry out, meaning that mucous membranes must work harder, producing more mucus to keep the cavity lined. As a result, the nasal cavity can fill up with mucus. At the same time, when air is exhaled, water vapor in breath condenses as the warm air meets the colder outside temperature near the nostrils. This causes an excess amount of water to build up inside nasal cavities. In these cases, the excess fluid usually spills out externally through the nostrils. Inflammatory Infection<unk>  can be a symptom of other diseases, such as the common cold or influenza. During these infections, the nasal mucous membranes produce excess mucus, filling the nasal cavities. This is to prevent infection from spreading to the lungs and respiratory tract, where it could cause far worse damage. It has also been suggested that<unk>  is a result of viral evolution, and may be a response that is not useful to the host, but which has evolved by the virus to maximise its own infectivity.<unk>  caused by these infections usually occur on circadian rhythms. Over the course of a viral infection, sinusitis (the inflammation of the nasal tissue) may occur, causing the mucous membranes to release more mucus. Acute sinusitis consists of the nasal passages swelling during a viral infection. Chronic sinusitis occurs when one or more nasal polyps appear. This can be caused by a deviated septum as well as a viral infection. Allergies Pollen grains from a variety of common plants can cause an allergic reaction.<unk>  can also occur when individuals with allergies to certain substances, such as pollen, dust, latex, soy, shellfish, or animal dander, are exposed to these allergens. In people with sensitized immune systems, the inhalation of one of these substances triggers the production of the antibody immunoglobulin E (IgE), which binds to mast cells and basophils. IgE bound to mast cells are stimulated by pollen and dust, causing the release of inflammatory mediators such as histamine. In turn, this causes, among other things, inflammation and swelling of the tissue of the nasal cavities as well as increased mucus production. Particulate matter in polluted air and chemicals such as chlorine and detergents, which can normally be tolerated, can make the condition considerably worse. Crying<unk>  is also associated with shedding tears (lacrimation), whether from emotional events or from eye irritation. When excess tears are produced, the liquid drains through the inner corner of the eyelids, through the nasolacrimal duct, and into the nasal cavities. As more tears are shed, more liquid flows into the nasal cavities, both stimulating mucus production and hydrating any dry mucus already present in the nasal cavity. The buildup of fluid is usually resolved via mucus expulsion through the nostrils. Non Inflammatory Head trauma If caused by a head injury,<unk>  can be a much more serious condition. A basilar skull fracture can result in a rupture of the barrier between the sinonasal cavity and the anterior cranial fossae or the middle cranial fossae. This rupture can cause the nasal cavity to fill with cerebrospinal fluid. This condition, known as cerebrospinal fluid<unk>  or CSF<unk> , can lead to a number of serious complications and possibly death if not addressed properly. Other causes<unk>  can occur as a symptom of opioid withdrawal accompanied by lacrimation. When it occurs after exercise, it is a symptom of exercise-induced rhinitis. Other causes include cystic fibrosis, whooping cough, nasal tumors, hormonal changes, and cluster headaches. Due to changes in clinical practice,<unk>  is now reported as a frequent side effect of oxygen-intubation during colonoscopy procedures A simple, innovative way to reduce rhinitis symptoms after sedation during endoscopy" by Nai-Liang Li, et al., Canadian Journal of Gastroenterology, 2011, Feb; volume 25(2): pages 68–72..<unk>  can also be the side effect of several genetic disorders, such as primary ciliary dyskinesia.
Rhinorrhea
Cerebrospinal fluid rhinorrhoea
Creatorrhea
Logorrhea 
Leukorrhea
Gonorrhea
Blennorrhea
Aerobic vaginitis