Runny Nose

A runny nose, medically termed rhinorrhea, is the passage of more fluid or mucus than usual from the nose. This discharge may be watery, clear, thick, sticky, unilateral, or bilateral, and its appearance can help in understanding the underlying cause. Runny nose is a very common symptom and is most often associated with upper respiratory tract infections and allergic processes. Even so, its duration, associated symptoms, and especially whether it is one-sided alter its clinical significance. ^[1][2][3]

A runny nose is often seen together with sneezing, nasal congestion, postnasal drip, throat irritation, cough, or reduced sense of smell. In some people it may increase in cold weather, with spicy foods, or with certain odors; this pattern may support nonallergic rhinitis. In children, prolonged, foul-smelling discharge from one nostril deserves special attention, because conditions such as a foreign body can present this way. Thus, although it seems simple, a runny nose is a symptom that is highly sensitive to context. ^[1][2][4]

What Causes a Runny Nose?

Most common causes: common cold and allergy

One of the most common causes of a runny nose is viral upper respiratory infection. In the common cold, the discharge usually begins together with sore throat, sneezing, fatigue, and sometimes a mild fever. The discharge is often more watery in the first days and may change in consistency over time. This change does not always mean bacterial infection; the duration of symptoms and other findings such as facial pain and fever are considered together. ^[1][3][5]

In allergic rhinitis, on the other hand, clear discharge, nasal itching, repeated sneezing, and watery eyes are more prominent. Symptoms may increase in certain seasons and may be related to triggers such as pollen, house dust, animal dander, or similar exposures. Allergic and viral causes can sometimes look alike; however, marked itching and eye symptoms provide clues in favor of allergy. Even so, the final distinction is made based on symptom duration and the overall clinical picture. ^[2][3][5]

Other possible causes

A runny nose may also be related to nonallergic rhinitis, sinusitis, environmental irritants, hormonal changes, and certain structural causes. In nonallergic rhinitis, the discharge may be triggered by irritants such as perfume, smoke, temperature change, or spicy foods. In sinusitis, facial fullness, headache, reduced sense of smell, and sometimes fever may accompany the discharge. Unilateral, foul-smelling discharge suggests the possibility of a foreign body in children. ^[1][2][6]

In adults, evaluation may be needed for structural problems or other ear, nose, and throat causes when unilateral discharge persists for a long time or occurs together with recurrent nosebleeds or congestion. The color of the discharge alone is not diagnostic; clear discharge does not mean unimportant, and colored discharge does not necessarily mean bacterial. The duration of symptoms, facial pain, fever, congestion, and general condition must all be considered together. ^[1][3][6]

How Do Associated Findings Change the Picture?

A runny nose accompanied by sneezing, itchy eyes, and watery eyes may support an allergic framework. Sore throat, cough, fatigue, and mild fever may be more consistent with a viral infection. A feeling of pressure in the face, headache, and a clear reduction in the sense of smell may suggest that the sinuses are also involved. In summary, a runny nose gains meaning not in isolation, but together with neighboring symptoms. ^[1][3][5]

Unilateral, foul-smelling, bloody, or long-lasting discharge carries a different level of importance. In children especially, this appearance may indicate a foreign body lodged in the nose. In adults, chronic unilateral discharge and congestion may point to different ear, nose, and throat causes. In addition, if shortness of breath, wheezing, or widespread allergic symptoms accompany it, the picture may not be limited to the nose alone. ^[1][2][6]

What Is Asked During Medical Evaluation?

Clinicians ask how long the runny nose has been present, whether it is seasonal or continuous, whether it is unilateral or bilateral, and how it relates to itching, sneezing, and eye symptoms. In children, a history suggesting a foreign body is important; in adults, cigarette smoke, occupational exposures, and contact with allergens are relevant. Nasal congestion, facial pain, fever, nosebleeds, and changes in smell help guide the evaluation. ^[1][2][3]

On examination, the appearance of the nasal mucosa, the type of discharge, the presence of polyps or structural obstruction, and when necessary the ear and throat area are evaluated. The goal is not merely to say “there is discharge,” but to understand whether it fits with infection, allergy, irritation, a foreign body, or another ENT-related cause. Runny nose is a common symptom, but particularly when it persists or follows an unusual pattern it requires diagnostic attention. ^[1][2][6]

When May It Be Considered More Serious?

Faster evaluation is needed if a runny nose is accompanied by high fever, marked facial swelling or pain, shortness of breath, inability to feed in a child, marked fatigue, or a poor general condition. Unilateral foul-smelling discharge, bloody discharge, or long-lasting unexplained symptoms are likewise important. The possibility of a foreign body should be considered promptly, especially in children. ^[1][2][6]

Runny nose is most often related to common causes such as the common cold or allergies; however, it can sometimes also be a sign of other ENT problems. This content does not replace diagnosis. Individual medical evaluation is important when the symptom is prolonged, unilateral, foul-smelling, or accompanied by breathing problems. ^[1][2][3]

It is also important to assess runny nose according to duration. Acute discharge limited to a few days is more often associated with viral infections or short-term irritant exposure, whereas discharge lasting for weeks, recurring periodically, or continuing year-round may favor allergic or nonallergic rhinitis. Especially in school-age children, chronic nasal symptoms that affect sleep quality, feeding, or attention span should not be interpreted simply as “a cold that lasted too long.” The impact of the symptom on quality of life is also part of its clinical weight. ^[2][3][6]

The consistency of the nasal discharge and accompanying complaints of postnasal drip also shape how patients describe the problem. In some people, the main issue is not discharge flowing out from the front of the nose, but mucus draining backward, causing throat clearing, nighttime cough, or morning throat irritation. In that case, the complaint is still considered within the rhinorrhea spectrum. Not reducing the symptom only to visible anterior nasal drainage is especially helpful in understanding chronic ENT complaints. ^[1][2][6]