The cause of nasal discharge can be identified based on the type of discharge.
The inner lining of the nose consists of mucus membrane that contains mucus-secreting glands. Mucus is a thin secretion made up of water, antibodies and proteins. The mucus helps to keep the nasal passages moist and prevent dust or infective particles suspended in the air from reaching the lungs. In some conditions, the mucus production increases and manifests in the form of a running nose. Inflammation of the nasal mucosa is referred to as rhinitis. The excess mucus may drip down the throat, resulting in irritation and frequent clearing of throat. This condition is referred to as postnasal drip. The excess mucus can also block the eustachian tube which connects the nose with the ear resulting in ear infection and pain.
The cause of nasal discharge can often be identified by examining the patient. The type of discharge gives a clue to the underlying cause. For example -
- A thin and clear discharge indicates common cold, flu or allergy.
- A thick and yellowish or greenish yellow discharge indicates bacterial infection.
- A watery discharge following a head injury may indicate leakage of cerebrospinal fluid
- A blood-streaked nasal discharge may be due to aggressive blowing of the nose or excessive dryness of nasal membranes.
- A thick, green colored, one sided and foul smelling discharge may indicate the presence of a foreign body in the nose.
Various causes of nasal discharge are listed below:
Allergic Rhinitis: Allergic rhinitis is a condition characterized by nasal itching, swelling and watery discharge. It is also accompanied by other symptoms like itching and watering of eyes with swelling of eyelids, sneezing and rash with itching. Some patients may show the presence of additional symptoms like cough, wheezing and the presence of nasal polyps. The patients usually have other people in the family suffering from the same condition. Symptoms may be seasonal i.e. appear when the person is exposed to pollen in spring and summer months, or perennial, i.e., caused by substances that the patient is exposed to all year around like dust mites and cockroach debris.
Infective Rhinitis / Rhinosinusitis: Infective rhinitis or rhinosinusitis (inflammation of nose and sinuses) is caused by bacterial, viral and rarely fungal infection.
- Viral Infection: Infections with viruses like rhinoviruses and adenoviruses result in viral rhinosinusitis or common cold. Symptoms include clear mucus secretion, decreased ability to smell and nasal congestion. Other associated symptoms include malaise, headache and cough. The nasal mucosa appears red and swollen on examination. Symptoms usually last for less than 10 days and resolve without treatment. However, if the infecting virus is the influenza H1N1 virus, the patients may require treatment especially if they belong to groups that are at a risk for complications like very young or old patients, pregnant women, patients with respiratory or immune disorders or adolescents younger than 19 years receiving aspirin therapy.
- Bacterial Infection: Infection of the nasal mucosa with bacteria usually follows a viral infection. The patient experiences thick, yellow-green nasal discharge. In addition, the patient also experiences loss of sensation of smell, a blocked nose and bad breath. Associated symptoms include fever, headache, facial pain and cough.
- Fungal Infection: Fungal infection of the nose and sinuses is rare and affects only patients with reduced immunity like patients with diabetes, kidney disease or those undergoing treatment for cancer. The nasal discharge is usually clear or straw colored. The patient complains of facial pain and sometimes visual symptoms. The black fungus may be obvious on examination of the nose.
Vasomotor Rhinitis: Vasomotor rhinitis is a non-allergic, non-infective type of rhinitis in which the patient, often an elderly, suffers from clear watery discharge. The discharge may be stimulated by conditions like warm or cold air, odors, scents, light or particulate matter.
Foreign Body in Nasal Passage: A foreign body stuck in the nasal passage causes unilateral and foul smelling nasal discharge. The presence of a foreign body should especially be suspected in children with such symptoms.
CSF Rhinorrhea: A head injury could lead to a fracture in the skull and result in the leakage of fluid surrounding the brain (called the cerebrospinal fluid) through the nose. Thus, presence of a clear nasal discharge following a head injury should be treated as an emergency.
Medications: Medications like aspirin, ibuprofen, beta blockers, antidepressants, oral contraceptives or drugs used to treat erectile dysfunction are some of the medicines which can result in a clear nasal discharge. Treatment with local nasal decongestants can cause a rebound increase in congestion and clear nasal discharge once the effect of the medicine is over.
Hormonal Changes: Changes in the hormone levels due to pregnancy, oral contraceptives, menstruation and hypothyroidism result in increased congestion and watering of the nose.
Emotional States: Nasal discharge that accompanies crying is due to passage of the tears through a small opening on the inner side of the eyelid into the nose.
Hot and Spicy Foods: Hot and spicy foods stimulate the mucus glands to increase nasal secretion.
- Current Medical Diagnosis and Treatment 2012
- Rhinitis (Nasal Allergies) - (http://www.aafa.org/display.cfm?id=8&sub=16&cont=66)