By the time we pass childhood, most of us are familiar with having a runny nose. Those who grow up in places where the winters are cold are familiar with coming inside and having the nose run for a short while, or noticing the same after having a bowl of hot soup. Others know the runny nose and flushing of the face after eating hot, spicy foods such as chili or hot peppers. There are the familiar "head-colds," which produce a runny nose, along with the usual stuffy, sneezy, slightly feverish feeling which most learn to recognize. Most donít worry about a runny nose under these circumstances. However, if the nose runs all the time, one eventually begins to wonder about being allergic to something, prompting a visit to the doctor.

Persistent runny nose or stuffiness of the nasal passages affects at least 15 percent of the population. In fact, half of those have allergy as the cause, but the rest have some other source for the problem. It is important to differentiate between different causes of runny nose because the treatment and management is different depending on the nature of the problem.

The role of the nose is partly to detect smells, and partly to warm, humidify and filter the air before it enters the lungs. In order to accomplish this, the nose must keep itself moist and keep itself from drying out. The moisturizing mucus is fluid that is filtered from the serum of our blood by capillaries which supply certain cells and glands in the lining of the nose and sinuses. The small amount of discharge which is usually produced is 90 to 95 percent salty water, and 2 to 3 percent a viscous chemical called mucin. Normally, during certain phases of life, such as puberty or pregnancy, there may be more nasal discharge than usual, caused by hormonal triggers.

Temporary runny nose may be caused by changes in humidity or temperature. Coming inside from the cold outdoors to a warm room, or having the heater on at night which dries the nose may cause the nose to temporarily go into overdrive in an attempt to flush and remoisturize itself. In this case there is no allergic reaction involved. The capillaries which bring blood to the inner surface of the nose temporarily open up their tiny pores, and the result is the sudden leak of clear serum-like fluid through the nasal opening. A persistent exaggerated form of this response, called vasomotor rhinitis, occurs in some individuals. In such cases the pores in the capillaries become stuck on "open," and are unable to close again as they usually do. Such persons have a clear, runny nose persisting throughout the day an night, regardless of obvious outside triggers. Why the capillaries remain leaky in this way is not known. Short of passage of time, there is usually no cure for vasomotor rhinitis, only management with decongestants or certain medications.

On the opposite end of the spectrum, certain individuals, especially as they become older, damage the lining of the nose, which becomes unable to produce the thin, runny protective mucous fluid. These persons have a persistent thick, dry, gluey mucous in the nose with resultant irritation or perpetual post-nasal drip.

By far the most common cause of persistent runny nose is allergy, though hay-fever allergy also commonly produces other symptoms such as sneezing, itchy nose, and runny itchy eyes. Allergy is a specific process which is driven by overactive biochemical reactions within the tissues of the nose and the blood triggered by various otherwise harmless biochemical substances. The name "hayfever allergy" comes from a time when the majority of the population farmed for a living, and allergic runny noses were most common while cutting the hay. In fact, ragweed and grass pollen are still common triggers for allergic rhinitis, but so are animal dander, feathers, and mites. The allergic process triggers the release of certain chemicals. The nasal lining attracts blood cells called eosinophils, and immune globulin E is released which in turn acts on so-called mast cells to release histamines, which generate an inflammatory reaction. Antihistamines and anti-inflammatory medications are used to dampen this process. Interestingly, simply inhaling warm, humid air has been shown to reduce the severity of both allergic and vasomotor rhinitis. A long, hot shower, or warm salt water rinses to the nose, may be good initial non-medication treatments during allergy season.

Chemicals which irritate the nose can cause symptoms similar to allergy or vasomotor rhinitis. Persons who do not protect their nose while working with solvents, chlorine, paints, varnishes, or gasoline will experience this. Also, persons using a strong decongestant nose spray for extended periods will get a chronic irritation of the nose. The cure is the discontinuation of the decongestant spray.

Infectious organisms which normally don’t belong in the nose can also cause a runny nose. Most familiar is the common cold, which is caused by a virus. Normally the nasal passage has certain colonies of bacteria, but in some persons, the normal colonies may be overrun by certain other bacterial invadors, including staphylococcus or chlamydia pneumoniae. Rarely even yeast or fungus may overgrow especially in those who have used antibiotics for prolonged periods. Bacterial colonization may produce a crusty, sometimes bloody discharge from the nose. In such cases the inside lining of the nose is red instead of the normal pale pink, similar to the inside of the cheeks. Antibiotics in the ointment or pill form may help, though colonies are hard to eradicate, especially in persons who may have problems with immune deficiency.

Chronic runny nose may cause the sinuses to fill up with fluid and mucous, and this fluid becomes a warm and cozy place for bacteria or other infectious organisms to grow. Sinus infection usually produces a pressure feeling over the forehead or cheekbones. The stopped-up sinuses may result in reduced resonance and the well-known "nasal sound" to the voice, and possibly the loss of the sense of smell and taste.

It is important to differentiate between the various causes of runny nose, because treatment is somewhat different for each problem. In general most nasal problems may benefit from warm humid air produced by a hot shower, a humidifier, or warm salt water rinses. Vasomotor rhinitis responds to ipratroprium (Atrovent) prescription nose spray. Allergic rhinitis responds to elimination of the allergic irritant, and to specific medicines which block the allergic response, including leukotriene inhibitors, cortisone-based sprays and antihistamines. Chemically driven irritation of the nose responds to elimination of the chemical agent. Infected nasal passages are managed with antibiotic ointments such as Bacitracin with zinc, or antibiotics in the pill form. Sinus infections may require an extended course of antibiotics along with some decongestants.

If simple measures or "tincture of time" donít stop your nose from running, see your doctor for an accurate diagnosis and specific suggestions tailored to your problem.