Something irritating or inflaming the nasal tissue of the nose is what causes it to become runny. To a stop a runny nose, a person will either need to stop what is irritating or inflaming their nose or take medications that will help reduce the inflammation and production of mucus.

A runny nose is the body's way of getting rid of any germs that might be irritating or inflaming it. The nose produces clear mucus, which can turn yellow or green after a few days.

In medical literature, professionals call a runny nose . A person may have a runny nose because they are allergic to something, due to a viral or bacterial infection, or as a result of of environmental factors such as temperature.

Below, we take a look at some of the common causes of a runny nose.

Dog and cat under blanket for animal dander allergy
Animal dander is a common allergen that can cause a runny nose.

According to the , allergies occur because a person's immune system reacts to a particular substance, or allergen.

Some common allergens include pollen, , and dust.

This reaction can cause several symptoms to develop, including a runny nose, sneezing, itchy eyes, a scratchy throat, or coughing.

According to the , the typical treatment options for allergies include using:

Antihistamines work by blocking the receptors in a person's body that cause inflammation. According to an article in the journal , a person can take second-generation antihistamines up to four times above the recommended dose if the recommended dose does not help after a period of time.

According to the , decongestants work by reducing the swelling in the nose that is causing the congestion.

Nasal steroids also reduce swelling in a person's nose, but they do so using a different mechanism.

According to the , many viruses can cause the common cold, though the most common is rhinovirus.

A cold can cause a person to have a runny nose. Other symptoms of a cold can include:

Colds are usually worse during the second or third day and can last for as long as 2 weeks in some cases.

Colds do not require any treatment. According to the CDC, a cold will get better on its own.

To help themselves feel better, however, a person should "."

Sinusitis shares some symptoms with the common cold.

Sinusitis is an infection of the sinuses. Sinusitis occurs when fluids cannot leave a person's sinuses, which allows germs to develop.

The cause is usually a virus, but occasionally, it can be a bacterial infection.

According to , most people who have a cold will also have infected sinuses.

As well as a runny nose, sinusitis has other symptoms similar to those of a cold.

A medical professional can determine whether a person's sinusitis is due to a bacterial infection or a virus. If it is due to a bacterial infection, they may prescribe antibiotics.

If a person's sinusitis occurs because of a virus, resting at home should be enough to treat the infection.

According to an article in the journal , nonallergic rhinitis causes the symptoms of rhinitis without the cause being allergies. Such symptoms include a blocked or runny nose and sneezing.

Triggers for nonallergic rhinitis include changes in the weather, exposure to caustic odors or cigarette smoke, and changes to atmospheric pressure.

For example, an older study in the notes that people exposed to cold air, such as those who ski, can experience cold air-induced rhinitis. The study found that ipratropium bromide nasal spray may be effective at reducing cold air-induced rhinitis.

Generally, however, will subside when the person moves to an area with warmer air.