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Updated 13 February 2013

Hay fever

Hay fever is an allergic reaction to small particles of plant or animal protein

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What is hay fever?

The term hay fever is a misnomer: the condition is not caused by hay, nor does it produce fever. Hay fever is an allergic reaction to small particles of plant or animal protein that weigh little enough to be carried through the air and get deposited on the membranes of the eyes, nose and throat. In some people the immune system is overactive and identifies normally harmless particles as dangerous, producing an excessive reaction.

This reaction results in the release of powerful chemical agents of which histamine is the best known. These substances cause very severe swelling of the mucous membrane lining the nasal passages and conjunctiva of the eyes, intense itching and sneezing and the production of large amounts of watery mucus.

Allergic nasal disorders are divided into two main types: the seasonal form which is known as seasonal allergic rhinitis or more commonly as hay fever, and secondly the year-round form known as perennial allergic rhinitis.

Symptoms of the former is typically that of nasal itchiness, sneezing and a runny nose. Nasal blockage is less common. In the latter there may be little symptoms of nasal itchiness, sneezing or a runny nose with the symptoms being mainly that of nasal obstruction. Many individuals however have a combination of both.

With seasonal hayfever, spring (September to November) is often a particularly miserable time for allergy sufferers. Just as winter ends and the tree blossoms appear, asthma, hayfever, allergic conjunctivitis and even eczema begin to flare up. However, for some individuals allergic only to plants flowering in autumn, this may be the problem time for them.

What are the symptoms of hay fever?

A person may have any or all of the following:

  • Severe bouts of sneezing, especially in the morning
  • Intense itching of the nose and of the palate and even the ear canals
  • Watery nasal mucus
  • Stuffy nose all the time or during specific seasons
  • Itchy and teary eyes
  • Eyes are sensitive to light
  • Reddened, pebbly lining in the lower eyelids
  • Frequent throat-clearing
  • Breathing through the mouth
  • Snoring
  • Rabbit-like movements of the nose
  • A horizontal crease across the nose as a result of constant rubbing
  • Repeated nosebleeds
  • Dizziness or nausea, related to ear problems
  • Nasal voice because of blocked nasal passages
  • Dark circles under the eyes as a result of pressure from blocked nasal passages on the small blood vessels
  • Irritability
  • Headaches because of pressure from inside the nose or from the sinus canals being blocked and a negative pressure-sinus headache

Nasal blockage associated with headache, persistent dripping at the back of the throat and bad breath, suggests chronic sinusitis rather than rhinitis.

What causes hay fever?

Allergens which cause hay fever are the pollens of grass, trees and a few weed species, all of which are wind-pollinated. It is only the small, light wind-borne pollens which cause the allergic reaction in the nose. Occasionally fungal spores are implicated, but as these usually have a year-round distribution, seasonal flare-ups are very unlikely. Certain tasks such as mowing the lawn during the pollen season will aggravate symptoms of hay fever.

Perennial allergic rhinitis (that occurs all year round) is mainly caused by house dust mite, animals and moulds.

Pollen levels are usually highest in the mid morning, and larger amounts are present on hot windy days. During hot humid weather, especially after thunderstorms, pollen grains tend to rupture releasing fine starch granules into the air which are highly allergenic and can penetrate deeply into the lungs.

Early springtime hay fever is most often caused by pollens of common trees. Late springtime pollens come mostly from grasses. Colourful or fragrant flowering plants, such as many garden plants, rarely cause allergy, because their pollens are too heavy to be airborne. Unlike grasses, trees and weeds, which are wind-pollinated, garden plants are pollinated by insects, which carry their heavy, sticky pollen.

Pollinating seasons for grasses, trees and weeds are fairly consistent from year to year. These seasons vary according to geographic region. Hay fever season extends beyond the period of late summer into early autumn, as this is the time when many weeds release their pollen. In South Africa, because of the warm climate, our grass seasons are very long and may continue for 9 months resulting in symptoms for long periods.

Treatment

It is impossible to avoid the allergens which cause this form of rhinitis, e.g., grass pollens, so medical treatment is unavoidable in most cases. Speak to your doctor about the most appropriate treatment for you. Treatment for hay fever is divided into 4 main groups:

Antihistamines

Recent developments in this field have seen the introduction of a new class of anti-histamines which no longer produce excessive drowsiness. In addition some of these new anti-histamines need only be taken once a day, which is a big advantage. However, in some individuals, the amount of histamine being released in response is greater than the typical and correct dose of antihistamine being taken, and a higher dose may be required. Discuss this with your doctor.

Mast cell stabilizers

The only effective preparation in this group is sodium cromoglycate (Rynacrom) nasal spray. This is a very safe spray with no known adverse side-effects and works well in hay fever sufferers (but not in all).

Steroid sprays

Steroid sprays reduce and control the impact of many of the mediators that can cause inflammation in the nose. These medications improve all symptoms of allergic rhinitis and are the strongest medications available for the treatment of allergic rhinitis.

There are several topical steroid sprays available which are effective in severe cases of hay fever. The most familiar of these is probably beclomethosone dipropionate (Beconase), which is available as an aerosol spray or in aqueous form.

Generally speaking, if symptoms are mostly that of a runny nose, sneezing and itching eyes, then steroid sprays will be less effective than antihistamines. However, if nasal blockage is a predominant symptom, then antihistamines on their own will not be very effective – nasal steroids will be required. If the blockage is severe, than an aqueous form is preferred over the aerosol spray. When using the aqueous spray, lie back on your back with your head dangling over the edge of the bed to allow the spray to penetrate as deep as possible.

Desensitisation:

This is a process whereby steadily increasing amounts of a known allergen, e.g. grass pollen extract, are injected beneath the skin of the upper arm. The injections are given at weekly intervals at first, and later on can be given every 6 weeks for a period of 3 years. Eventually the patient becomes tolerant of the allergen and no longer reacts adversely when exposed to that particular allergen. This is particularly effective if one is allergic to only one allergen. Consult your doctor on whether you can be desentitised from your allergy.

Read more:
Keeping your home clear of dust mites
Get the ay-Tissuesss out of your life

Updated by Dr H Steinman, July 2007

 
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