The causes of persistent rhinitis can be divided into allergic and non-allergic.
ALLERGIC RHINITIS
The most common allergies causing rhinitis are pollen (hay fever), house dust mite and pets, most commonly cats. Hay fever is seasonal and occurs during a particular period each year.
Symptoms of allergy in the nose are due to the immune system reacting to the allergen (the individual cause of the allergy). Cells in the lining of the nose release histamine and other chemicals when they come into contact with the allergen. This causes inflammation in the nose with swelling, excess mucus production and irritation. Allergic rhinitis can be associated with asthma and eczema and can run in families.
NON-ALLERGIC RHINITIS
Rhinitis commonly occurs without an allergic cause and there is often no identifiable cause for the condition. Many factors can influence the nasal lining however including:
- Changes in temperature or humidity
- Hormonal changes e.g. during pregnancy
- Food and drink, e.g. alcohol
- Emotion such as stress and anxiety
- Medication. Some medications can have side effects on the nose e.g. blood pressure medication and the contraceptive pill
- Use of decongestants
Rhinitis medicamentosa is the name given to rhinitis that can occur due to the overuse of nasal decongestant sprays. These sprays are used to relieve a blocked nose and they reduce swelling inside the nose by causing blood vessels in the nose to constrict. However, with prolonged use, they cause rebound nasal congestion which is more severe than the original swelling. The temptation is to use yet more decongestant and a vicious circle can be set up. A similar problem can occur in people who abuse cocaine.
In some people, no cause for their persistent rhinitis is found and it is called idiopathic or vasomotor rhinitis.