A runny nose is almost always a sign of a cold or flu. However, frequent occurrences can also be the sign of an allergy to dust, dander or another allergen in the air.

Although runny noses are mostly temporary symptoms, they can be very uncomfortable. With some conditions, they can present with additional symptoms, like coughing, a sore throat and snoring.

If your runny nose lasts for longer than 1 week, or if you additionally experience other symptoms, you should see a doctor for further assessment. Following an inspection and a review of your symptoms, the doctor can identify an underlying cause and initiate the most appropriate treatment.

1. Cold or flu

A runny nose is almost always associated with a cold or flu. It is often accompanied by other symptoms, like sneezing, headache, coughing, sore throat and even a low-grade fever. Runny noses with viral infections usually last for about 10 days, and are not of particular clinical concern. The body is usually able to fight the virus and manage the symptom on its own. Learn more about the difference between a cold and a flu.

What to do: To speed up recovery from a cold or flu, you should rest, drink plenty of fluids, eat a balanced diet, and avoid abrupt changes in temperature. Check out other home remedies for a cold or flu that you can use to treat mild symptoms at home.

2. Respiratory allergies

Allergic reactions generally cause inflammation of the respiratory airway, which can lead to a runny nose. Although it can present very similarly to a cold, an allergy will often have other, more unique symptoms, like tearing eyes, sneezing and heaviness in the nose area.

In addition, allergies and a runny nose are often triggered around the same time of the year. They are especially prevalent in the spring, when there is a higher quantity of allergies in the air, like pollen, dust and fur.

What to do: If you suspect you have allergies, you should try to identify what triggers them, so that you can avoid it when possible. If you are unable to identify what is causing your symptoms, the doctor may order allergy testing and prescribe anti-histamines and decongestants to manage your runny nose and other symptoms in the meantime.

3. Sinusitis

Sinusitis is an inflammation of the nasal cavities that can cause a runny nose. The discharge eliminated from the nose is often yellow or green in color, which is indicative of an infection. In addition to a runny nose, you may also have other symptoms, like a fever, headache, and facial heaviness. This discomfort can be felt in the eyes and often worsens when you tilt your head forward.

Read more about the symptoms associated with a sinus infection.

What to do: Sinusitis is usually treated with nasal sprays and medications that reduce headaches and fever. If the sinusitis is caused by a sinus infection, it can be treated with antibiotics as prescribed by the doctor. See other home remedies for sinus infections that you can use to complement your prescribed medical treatment.

4. Rhinitis

Rhinitis is an inflammation of inner lining of the nose. It can cause a constant runny nose that takes time to resolve. Although it can present very similarly to an allergy (runny nose with sneezing and tearing of the eyes), it is not an immune response, and therefore requires different treatment.

What to do: Prescription nasal decongestants are often recommended by the doctor to treat rhinitis, however nasal irrigation can also help to remove excessive nasal discharge. Read more about how to perform a nasal irrigation at home.

5. Nasal polyps

Although this is a more rare finding, nasal polyps deep within the nose can also cause a constant runny nose. Polyps are small, benign tumors that usually do not cause any symptoms. However, polyps that grow within the nose can lead to a runny nose, as well as changes to taste and snoring.

What to do: Normally, nasal polyps do not need any specific treatment. However if symptoms are constant and do not improve, the doctor may prescribe corticosteroid nasal sprays to reduce swelling. If these sprays are not effects, surgical removal of the polyps may be necessary.

When to see a doctor

A runny nose is a common symptoms that is usually not of clinical concern. However, you should see a doctor if you also have any of the following symptoms:

A runny nose that lasts longer than a week
Green or bloody nasal discharge
Fever
Difficulty breathing or shortness of breath

These symptoms may be a sign of infection, which may need a specific treatment to prevent worsening.