Runny nose, which is also called rhinorrhea or rhinitis, may occur by itself or in combination with other symptoms such as sneezing and congestion, and usually goes away without medical treatment. You may develop a runny nose at any time, and having a runny nose may be annoying and cause difficulty with sleeping and breathing. The following information from the Mayo Clinic and the National Library of Medicine explain the causes of a runny nose.
Allergies are a common cause of a runny nose and often cause additional symptoms such as sneezing and nasal congestion. You may develop a runny nose due to seasonal allergies to airborne pollen or mold spores, and these allergies usually begin in late spring and last into summer. Other allergens, including pet dander, dust and foods such as dairy, soy and fish, may also cause a runny nose.
The use of certain medications and drugs may cause the nose and sinuses to produce too much mucus, resulting in a runny nose. Medications such as diuretics for high blood pressure, decongestants for stuffy nose and nasal sprays may cause a runny nose. Illegal drugs that are huffed, inhaled or snorted such as aerosol sprays and cocaine may cause a runny nose and nasal bleeding.
Viral and bacterial infections, especially those that affect your respiratory system, may cause a runny nose. Illnesses such as the common cold, bronchitis, sinus infections and influenza are common causes of a runny nose. Other infections such as chicken pox, respiratory syncytial virus, roseola and whooping cough are causes of a runny nose common among children.
Headaches may cause other symptoms besides pain, and these may include swelling, congestion and a runny nose. Cluster headaches in which several headaches occur within a short time can cause a runny nose. Head injuries such as being punched in the face or nose and other head trauma such as falls may also cause runny nose.
Hormonal changes may be a cause of runny nose in women. A runny nose is common during pregnancy and may persist for the entire duration of pregnancy, and pregnant women may not be able to take medications to relieve this symptom. Hormonal changes after childbirth, during premenstrual syndrome and menopause may also cause a runny nose.
Structural problems within the nose along with abnormal growths such as nasal polyps may cause a runny nose. A deviated septum or a broken nose may cause a chronic runny nose if the problem is not corrected. Objects stuck in the nasal passages may also cause a runny nose, and this is more common in children than adults.
Spending time outdoors in extreme weather conditions may cause excessive mucus production, resulting in a runny nose. Very low humidity during the winter months or at high elevations may cause a runny nose and nasal bleeding and irritations. Cold temperatures and bright sunshine or lights may also cause runny nose, especially after a prolonged exposure.