Hay fever (allergic rhinitis) is an allergy reaction affecting the lining of the nose that may be due to any one of several million different pollens, microscopic animals such as the house dust mite, skin scale or hair particles from animals.
When the sensitive moist membranes that line the nose first come into contact with the sensitising particle (an allergen), there is no reaction, but the body’s immune system is primed to react to the next invasion. On the second exposure, the large immunoglobulin proteins that act to defend the body against invasion by any foreign matter react violently. They cluster around mast cells that rupture and release histamine into the nasal tissues. This causes the tissue to become inflamed. After a few hours or days, the body destroys the histamine released, and the tissues return to normal.
10% of the population is affected by hay fever. The nose drips constantly and is clogged, the patient sneezes repeatedly, has bad breath, a constant drip of phlegm down the throat and red eyes, but it usually occurs for only a few weeks or months of the year. A secondary bacterial infection may develop to cause sinusitis. Blood tests may show an increase in certain types of cells and immunoglobulins.
Antihistamines and pseudoephedrine tablets or nose sprays (eg. tramazoline) are used to counteract the histamine released into the tissue and ease the symptoms, but some types of antihistamine may cause drowsiness. Steroid nasal sprays (eg. budesonide, beclomethasone, mometasone) and/or anti-allergy sprays used regularly prevent the nose from reacting to allergens.
Patients who suffer repeatedly can have blood or skin tests performed to determine exactly which dusts and pollens cause the hay fever and if a cause can be found, a course of twenty or more weekly injections may be given to permanently desensitise the patient.
The last resort is surgery in which part of the lining of the nasal cavity is removed by burning (diathermy), and some of the curly bones within the nose (turbinates) are cut out so that there is less membrane to secrete phlegm.