Causes of runny nose


Causes of runny nose

Viruses are the cause of a cold. In particular, the following pathogens are the originators:

  • Rhinoviruses
  • Coronavirus
  • Adenoviruses
  • Parainfluenza viruses
  • Respiratory Syncytial Virus (RSV)

After the cause of the transmission through direct contact with a sick person or through droplet or smear infection, the viruses nest in the cells of the body (host) and cause the typical symptoms of a cold.
The cold (hypothermia, freezing), which is often discussed as the cause of a cold, in all probability contributes to the development of a cold by weakening the immune system. As a result of this reduction in the immune system, the body becomes more susceptible to disease overall, so that the viruses can more easily remove their pathogenic (pathogenic) Can develop an effect and as a result a runny nose develops.


The pathogen as Cause of a runny nose are all viruses that can be divided into different virus families. The names of the virus families can be recognized by the ending "Viridae“(Viruses).
Rhinoviruses belong to the family of Picornaviridae, Influenza viruses to the Orthomyxoviridae and Parainfluenza viruses to the Paramyxoviridae.
With corona and adenoviruses, the family is called like the viruses themselves: Coronaviridae and Adenoviridae. The Respiratoy Syncytial Virus is one of the Pneumoviridae.
Human rhinoviruses as the cause of a runny nose comprise more than 100 subtypes, which in turn can be divided into two groups based on their mechanism of penetration into the cells (major group, minor group). The rhinoviruses are transmitted from person to person by droplet or smear infection.

The time until symptoms of the runny nose appear (incubation period) is one to four days and the sniff takes about seven days. An increase in rhinovirus infections occurs in spring and autumn; In principle, however, infection with a cold is possible all year round. The environmental resistance of these viruses is not particularly high, which is why these rhinitis pathogens cannot survive for long outside the host (target cells of the infection).
The name of Coronavirus results from its electron microscopic image, since its shell looks like a "halo" (corona) impressed. Several different sub-types are also known for this cold-causing virus, although in all probability not all are known yet. The transmission / cause of the runny nose occurs via droplet infection and, in addition to a cold, it can also occur without symptoms (asymptomatic) run. The infection rate is already high in children, which means that many infections with this virus occur at a young age.


Adenoviruses as further pathogens of a runny nose show a high environmental resistance and comprise around 50 subgroups. In addition to rhinitis, they cause other clinical pictures such as Conjunctivitis (Conjunctivitis) or Diarrheal diseases (gastroenteritis). Asymptomatic courses (without complaints) are also possible. It is passed on through droplet or smear infection, with infants and small children being infected by this virus and the level of contamination is correspondingly high. The incubation period is between a few and ten days.
Parainfluenza viruses that cause a cold have four subtypes. The transmission occurs through direct contact or through droplet infection. The first symptoms appear after an incubation period of three to five days. Infants and young children are also frequently infected with parainfluenza viruses, which is why the infection rate in children is between 50% and 90% lies.
That is also one of the rhinitis pathogens Respiratory syncytial virus are divided into two groups (A and B). The name comes from the fact that when cells are infected, they fuse with neighboring uninfected cells and form syncytia called "giant cells". These viruses are transmitted via droplet and smear infection and infect mainly infants and small children, so that even two-year-olds have a high infection rate. More serious illnesses also affect the elderly and those with weakened immune systems (Immunosuppressed).

Causes of an Acute Cold

Acute runny nose is in most cases a classic symptom in the context of a simple one cold or similar infection, e.g. the flu. One then speaks of an infectious rhinitis acute.

The triggers are almost always (cold) viruses that can be transmitted via droplet or smear infection, of which more than 200 different types are known.
The most common are rhinoviruses (from the Picornaviridae family), which in turn have over 100 different subtypes. Furthermore there are i.a. Respiratory syncytial, corona, parainfluenza and adenoviruses, especially in summer Coxsackie, entero and echo viruses in question. The fact that there is usually a large number of different subtypes of these as well explains why it is possible to develop such frequent illness without developing general immunity.

A nasal mucous membrane that has been attacked by dry room air or with poor blood supply due to hypothermia makes it easier for viruses to settle. Other favorable factors include a weakened one immune system (e.g. due to stress, lack of sleep, cold, other illnesses), irritation from chemical substances or cigarette smoke, systemic diseases (e.g. cystic fibrosis) or narrowing of the nasal cavity (due to polyps or a crooked nasal septum). Likewise, runny nose can be caused by infection with the Influenza virus which is the trigger for the "real" flu, which is much more severe than a common cold and starts very suddenly. Viral infectious diseases such as measles or chickenpox or the initial infection with a herpes simplex virus can be responsible for a runny nose.

Bacteria, on the other hand, are only rarely the cause of colds and if they do, then usually only in the context of a bacterial superinfection: through the nasal mucosa damaged in a viral infection or through the i.A. weakened immune system an additional infection with bacteria is favored, here mainly come Staph, streptococci and pneumococci in question. But sometimes bacterial infectious diseases such as Scarlet fever, Whooping cough, legionellosis, typhus, tuberculosis, even syphilis or gonorrhea (gonorrhea) accompanied by a runny nose, whereby the nasal secretion is yellowish to green in color, unlike in viral infections.
A special case is the rhinitis pseudomembranacea as a possible, rare appearance of diphtheria, in which the nasal mucosa is damaged by the formation of a pseudomembrane, so that a bloody-liquid runny nose occurs. Apart from that, the consumption of spicy food can lead to short-term sniffles or a "runny nose". In addition, a fracture of the base of the skull can lead to leakage Brain water (Liquor) get into the nasal cavities (rhinoliquorrhea), which could give the impression of having a cold.

Causes of a chronic runny nose

In principle, infections and the possible colds associated with them can occur if the immune system is permanently weakened (e.g. as part of a HIV infection) become chronic or keep recurring. In addition, there are many other different causes of chronic runny nose, some of which have their own names.

That is particularly common allergic rhinitis (Allergic rhinitis). This includes above all the so-called hay feverwhich only occurs seasonally during the spring, summer and (depending on the region) autumn months and can be triggered by a wide variety of grass and flower pollen. Many other allergens such as Animal hair, dust mites, mold, certain foods or different work materials such as Wood dust or hair dye can also cause a runny nose, but it persists throughout the year (perennial).

It is similar to the allergic runny nose vasomotor rhinitis (Rhinitis vasomotorica), but with the difference that no allergy or other cause can be proven, which is why the term in this regard NARE syndrome (Non-Allergic Rhinits with Eosinophilia Syndrome) is used. A dysregulation of blood vessels leads to inflammation of the nasal mucous membrane, which can obviously be favored by factors that promote blood circulation, e.g. extreme temperature changes, stress or alcohol. Various drugs, such as the Birth control pills, Beta blockers or ACE inhibitors can cause colds (especially the drying out and swelling of the nasal mucosa), but by far the most common is the rhinitis medicamentosa caused by long-term use (> 10 days) of decongestant nasal sprays. Due to a so-called rebound effect, the nasal mucous membrane swells automatically after stopping the spray because it has "got used" to the effects of the drug.

As Rhinitis sicca in turn, chronic runny nose with particularly dry, thinned mucous membrane that is caused by mechanical or toxic Exposure (e.g. chronic cocaine consumption or certain toxins / irritants in the workplace).

Another form is the Atrophic rhinitis (Ozaena or also "Stink nose"), in which the tissue shrinkage of the nasal mucous membrane promotes the colonization of germs and thus unpleasant smells as well as drying out and the formation of crusts.
In addition to the hereditary form, there are other causes for such a disease, e.g. Tumors of the nasopharynx, malformations of the nasal septum or surgery.

Sometimes, however, there is also an increase in volume of the lower and middle turbinates (Hypertrophic rhinitis) or developing on it Polyps Reason for chronic complaints.

Changes in hormonal balance, e.g. Possible causes in the context of pregnancy or an overactive thyroid, or systemic diseases such as Wegener's granulomatosis or sarcoidosis.

Also read: Runny nose during pregnancy

Causes of a bloody runny nose

Show up in the course of a cold Blood in nasal secretions, this is usually just a sign of a strong one irritation the mucous membrane.
Infections, allergies or other triggers of colds can attack the mucous membrane in such a way that it comes to light superficial bleeding. A dry nasal mucous membrane (e.g. due to dry room air) and mechanical loads such as a fall, the introduction of foreign objects, "Nose picking" or frequent blowing of the nose, but also high blood pressure and blood clotting disorders increase the risk.
Long-term use of decongestant nasal sprays or chronic cocaine use can also damage the mucous membrane.

In the case of a few infectious diseases, a bloody runny nose is even its own, specific symptom. So does the innate syphilis in children for a bloody-purulent runny nose, while diphtheria a bloody runny nose (Pseudomembranous rhinitis), in which the mucous membrane is damaged by the formation of a pseudomembrane. Purulent-bloody discharge, especially In connection with obstructed nasal breathing, bad smell from the nose and other complaints, it can also be an indication of a tumor of the nose or sinuses.

Mental causes

Psychological stress, especially emotional and professional stress (work, study, family, relationship, etc.) can do that immune system significantly weaken and thus favor infections or increase the risk of colds and extend the duration of the illness.
Permanent stress has a particularly negative effect on the immune system. Even allergic reactions or hypersensitivity reactions to food or other substances and the associated colds can be intensified. Psychological stress cannot trigger an allergy, but it can make the symptoms worse. It is also possible that allergy sufferers react allergic simply by thinking of the allergen in question or seeing it in a photo, especially if they have already been confronted with this allergen frequently.
In children in particular, strong psychological stress (e.g. pressure to perform) can also occur Epistaxis favor.

Causes of runny nose in babies and young children

As with adults, the main cause of the runny nose in babies and toddlers is a variety of different Viruses in question, which can be transmitted by droplet or smear infection.
Since the immune system of children is not yet fully developed, they are much more susceptible to colds than adults and are correspondingly more likely to get sick. In addition, the frequency distribution and severity may be different than in adults; for example, children are much more likely to suffer from human metapneumovirus and an infection with the respiratory system Syncytial Virus usually results in a more severe course in them.
A cold can also be used in the context of childhood illnesses, such as measles or chickenpox occur, but is usually not in the foreground as a symptom.
An additional infection with bacteria on the basis of a viral infection (bacterial superinfection) is also possible and can cause colds or make them worse.

Chronic runny nose also occurs in children; this is mostly done Allergies Against house dust mites or pollen, for example, but can also be caused by various irritants such as cleaning agents or perfume. Otherwise, all other rarer causes (e.g. polyps) that are also possible in adults are possible. Especially in small children, the complaints can also be caused by an undiscovered foreign body (e.g. a marble) can be triggered in the nasal cavity, which manifests itself in a one-sided, purulent runny nose. An enlarged pharynx should also be considered, this can also be responsible for a cold that does not heal in winter. Breasted breast milk that has got into the nasal passages can cause cold-like symptoms or a "runny nose" in babies.