Allergy occurs when a person's immune system reacts to substances in the environment that are harmless for most people. These substances are known as allergens and are found in dust mites, pets, pollen, insects, ticks, moulds, foods and some medicines.
Atopy is the genetic (inherited) tendency to develop allergic diseases. People with atopy are said to be atopic. When atopic people are exposed to allergens they can develop an immune reaction that leads to allergic inflammation(redness and swelling).
When a person who is allergic to a particular allergen comes into contact with it, an allergic reaction occurs. This begins when the allergen (for example, pollen) enters the body, triggering an antibody response. The antibodies attach themselves to special cells, called mast cells. When the pollen comes into contact with the antibodies, the mast cells respond by releasing certain substances, one of which is called histamine. When the release of histamine is due to an allergen, the resulting swelling and inflammation is extremely irritating and uncomfortable.
The most common causes of allergic reactions are:
pollen (grass, weed or tree)
foods such as peanuts, cow's milk, soy, seafood and eggs
cats and other furry or hairy animals such as dogs, horses, rabbits and guinea pigs
insect stings and tick bites
Medications used to treat allergies include:
Antihistamines block histamine release from mast cells, reducing symptoms. Non-sedating antihistamine tablets rarely cause drowsiness and are available from pharmacies without a prescription. Antihistamine nasal and eye sprays can also be used.
Intranasal cortiocosteroid nasal sprays (INCS) are very effective for treatment of moderate to severe allergic rhinitis (hay fever) when used appropriately and regularly. A prescription may be required for stronger dose INCS. Ask your pharmacist or doctor for advice.
Combination therapies (INCS and antihistamine) are used for treatment of moderate to severe allergic rhinitis (hay fever) and offer the combined advantages of both medications.
Medicated eye drops - ask your doctor or pharmacist for advice.
Adrenaline (epinephrine) - is used for first aid emergency treatment of life threatening severe allergic reactions (anaphylaxis). Adrenaline is usually given using an adrenaline auto injector and this can be given without any medical training.
If you think you may have an allergy your local pharmacist can advise you on what to do, or you may need to consult your doctor.