What is an “Allergy”?

The term ‘allergy’ is used only for the most extreme reactions on the spectrum of hypersensitivity.

For example, if your sinuses become blocked a few hours after you eat cheese, you can’t really say you’re ‘allergic’ to cheese. Correct would be to say your body is somewhat ‘intolerant’ of cheese, or that you are ‘hypersensitive’ to cheese.

How does the allergic hayfever reaction work?

The early stages

As we know, in a war there are innocent bystanders who are affected. Hayfever is no different.

The allergic reaction in hayfever gives rise to casualties in special cells called mast cells, an injured one of which will immediately release into the bloodstream a cocktail of inflammatory chemicals such as histamine, tryptase, chymase, kinins and heparin.

Before long, additional chemicals such as leukotrienes and prostaglandin D2 flood the bloodstream, interact with the earlier ones, and within minutes give rise to irritation, itching, swelling and leak­age of fluid from the cells in the form of sneezing, a runny nose and watering eyes.

The latter stages

Within four to eight hours, the above-mentioned chemicals have worked hard to recruit further inflammatory substances, and this results in ongoing inflammation, often extending to wider-ranging mucous membranes.

The symptoms produced are similar to those of the early stage, except that there is less itching and sneezing and there is an increase in congestion and the creation of mucus. The mixture of chemicals can even lead to muscle spasm, which causes tightening in the lungs and throat, as is experienced in asthma and laryngitis.

Fatigue, insomnia, irritability and a general feeling of malaise (feeling ‘out-of-sorts’) can arise from the late stage of reaction. Accompanying these can be ultra-sensitivity to bright light (particularly sunlight) and loud noise, together with a lowered pain threshold.

This invariably has a negative impact on quality of life, at least for the duration of the symptoms.

Did you know

Up to 35% of the population can find themselves sneezing uncontrollably due to a sudden burst of sunlight? This phenomena known as PSR (the photic sneeze reflex3) remains unexplained … though scientists have agreed on a detailed technical acronym for the condition that sufferers might prefer to use when describing their plight to an allergist – Autosomal-dominant Compelling Helio-Ophthalmic Outburst syndrome, or A.C.H.O.O.

Additional environmental insults that can lead to or worsen hayfever with an allergic reaction of their own include bleach, cigarette smoke, dust mites, fungal spores, latex, mould, mushroom spores, nickel, perfume, vehicle pollution also called ‘petrochemical smog’.

Urticaria

Urticaria, also called “hives” appears as lumpy, itchy, reddened skin that suddenly appear and disappear at unexplained intervals at various locations on the body.

Although it is not hayfever and is not triggered by common hayfever triggers, urticaria is a result of the release of histamine by the body similar to the hayfever reaction, and is thus often treated with the use of antihistamines.

It is rarely possible to accurately identify the direct cause of urticaria, though it is often possible that it has been caused by an infection, by medication, and sometimes by food or other factors including:

  • Foodstuffs such as shellfish, eggs, nuts, cheese, caffeine, and some fruit
  • Medication such as codeine, penicilin, aspirin, and some antibiotics
  • Food or drink containing tartrazine or other manufactured colourings
  • Animals such as cats, dogs and horses
  • Infection – viral (common cold, middle ear infection etc), parasitic, bacterial or fungal
  • Weather elements such as extreme wind, cold (most often cold water) heat, sunlight
  • Pregnancy – particularly during later stages
  • Insect bites including bee, flea, mosquito, sandfly, wasp

Urticaria can also result due to the presence of a pre-existing illness such as lupus, lymphoma, and thyroid disease.

Angio-oedema

Similar to urticaria but more severe, angio-oedema occurs deeper in the skin and effects mainly the face (lips and eyes) can cause swelling of the throat. Seek medical assistance immediately for treatment, and to ascertain what has caused the reaction.

Asthma

Why do many asthmatics also suffer from hayfever?

Asthma and allergic rhinitis are not too dissimilar to each other in that they both involve an immunologic (immune system related) inflammation which can be triggered by environmental factors such as pollen, dust, dust mites, smoke, chemicals, air temperature/pressure changes.

The nature of the inflammatory reaction in the asthma sufferer means their body is more likely than most to develop allergic rhinitis. Vice versa rhinitis sufferers are more likely to develop asthma.

Multiple studies in recent decades have concluded that 70-90% of asthmatics also have allergic rhinitis, and around 50% of allergic rhinitis sufferers have asthma.

If you experience tightening of the chest or difficulty breathing, it is possible you could have (or be developing) asthma, which requires additional treatment to your hayfever that your doctor can help you with.

Can hayfever medications be used in people with asthma?

The recommendation remains that asthma be treated as asthma, supplemented with allergic rhinitis treatment to improve nasal symptoms when both conditions are present. Allergic rhinitis occurs in the upper airways whereas asthma is in the lower airways so there are studies showing that better control of allergic rhinitis symptoms will improve asthma management. It is always best to speak with your GP to confirm a diagnosis of both asthma and allergic rhinitis and seek out the appropriate treatment strategies to ensure you are able to improve quality of life.

Antihistamines

– several studies show that the use of antihistamines (with or without pseudoephedrine) for the treatment of hay fever can improve asthma symptoms, and can reduce the amount of medication required to treat asthma. When continued antihistamine treatment is used with children for the treatment of infections, asthma is reported to be less likely to develop.

Corticosteroids

– such as those used to treat hay fever can have a positive effect on asthma symptoms. Systemic corticosteroids (taken orally) are known to effectively treat both asthma and hay fever at the same time, to some extent.

Allergen Immunotherapy

– also called ‘hay fever injections’ is considered an effective treatment option for Combined Allergic Rhinitis and Asthma Syndrome.

Sources:

  1. World Allergy Organisation. IgE in Clinical Allergy and Allergy Diagnosis. http://www.worldallergy.org/professional/allergic_diseases_center/ige/, accessed July 2014.
  2. World Allergy Organisation. Rhinitis and Asthma. http://www.worldallergy.org/public/allergic_diseases_center/caras/, accessed July 2014.
  3. Scientific American. http://www.scientificamerican.com/article/why-does-bright-light-cau/, accessed July 2014