A runny nose, also known as rhinorrhea, is a common symptom experienced by most people at least once in their lifetime. It is often a symptom of a viral infection, such as the common cold, which usually goes away after a few days.

However, there are cases when a runny nose occurs without any apparent cause or persists for an extended period. In this article, we explore some potential culprits behind an unexplained runny nose.

1. Allergies

Allergies are a common cause of a persistent runny nose. When exposed to an allergen, such as pollen, pet dander, or mold spores, the immune system produces histamine, which causes the nasal passages and blood vessels to swell.

This swelling results in an increase in mucus production and a runny nose. Allergic rhinitis, also known as hay fever, is a common type of allergy that causes symptoms such as sneezing, itchy eyes, and a runny nose.

2. Non-allergic Rhinitis

Non-allergic rhinitis is a type of rhinitis that causes a runny nose, sneezing, and nasal congestion without any known allergy.

The exact cause of non-allergic rhinitis is unknown, but it is commonly triggered by environmental factors such as pollution, smoke, changes in temperature, or humidity. Some people with non-allergic rhinitis may also experience nasal polyps, which are small growths in the nasal passages that can cause blockages and persistent nasal congestion.

3. Sinusitis

Sinusitis is an inflammation of the sinuses, which are the air-filled spaces in the bones of the face.

When the sinuses become inflamed due to infection, allergies, or environmental factors, mucus can build up and cause a persistent runny nose, facial pain, and pressure. Acute sinusitis usually goes away within a few weeks, while chronic sinusitis can last for several months or more.

4. Medications

Some prescription medications, such as blood pressure medications, antidepressants, and hormonal contraceptives, can cause a runny nose as a side effect.

If you experience a runny nose after starting a new medication, you may want to talk to your doctor about adjusting your dosage or switching to a different medication.

5. Hormonal Changes

Hormonal changes, such as those that occur during pregnancy or menopause, can cause a runny nose. These changes can lead to an increase in mucus production, which can cause nasal congestion and a runny nose.

Hormonal changes can also affect the immune system and make you more susceptible to infections that can cause a runny nose.

6. Structural Abnormalities

Structural abnormalities in the nasal passages, such as a deviated septum or enlarged turbinates, can cause blockages that lead to a runny nose.

Deviated septum is a condition in which the wall that divides the nasal passages is crooked, causing one side to be smaller than the other. Enlarged turbinates are small structures in the nasal passages that can become inflamed and swollen, causing blockages and a runny nose.

7. Neurological Conditions

Some neurological conditions, such as multiple sclerosis or Parkinson’s disease, can cause a runny nose. These conditions can affect the nerves that control the nose and cause an overproduction of mucus.

Other neurological conditions, such as cerebral spinal fluid leak, can cause a clear and persistent runny nose that worsens when leaning forward.

8. Foreign Bodies

A foreign body in the nasal passages, such as a small toy or food particle, can cause a runny nose. The foreign object can cause irritation and inflammation, leading to an increase in mucus production and a runny nose.

If you suspect a foreign object is lodged in your nasal passages, seek immediate medical attention to have it removed safely.

9. Environmental Irritants

Exposure to environmental irritants, such as chemical fumes, cigarette smoke, or air pollution, can cause a runny nose.

These irritants can cause inflammation and irritation in the nasal passages, leading to an increase in mucus production and a runny nose.

10. Idiopathic Rhinorrhea

Idiopathic rhinorrhea is a condition in which the nasal passages produce excessive amounts of mucus without any apparent cause. This condition is rare and may be associated with underlying conditions such as hormonal imbalances or autoimmune disorders.

If you have an unexplained runny nose, it’s important to see a doctor to determine the cause of your symptoms. Depending on the cause, treatment options may include medications, nasal sprays, or surgery.