Allergy is a condition when your body’s immune system overreacts to a substance that is usually harmless (allergen).The allergen may be inhaled, ingested, injected or contacted.There are many types of allergies, including atopic allergy (allergic rhinitis, eczema, and allergic conjunctivitis), food allergy (commonly caused by eggs, milk, seafood and nuts), insect sting allergy, drug allergy (most common allergens are penicillin-based antibiotics and vaccines) and environment allergy (pollen allergy and dust mite allergies).
More serious reactions include swelling of the throat and airways, wheezing, and loss of consciousness.
The most effective way of managing an allergy is by avoiding contact with the causative allergens.
If this cannot be achieved, medications may be needed to relieve the symptoms.
Commonly used anti-allergy medicines include antihistamines, corticosteroids, decongestants and montelukast.
These medicines are available in many dosage forms, such as tablets, capsules, inhalers, topical creams, ointments and injections.
In Hong Kong, most of the oral anti-allergy medicines can be bought in licensed medicine stores or pharmacies.However, you should seek advice from your family doctor or other healthcare professionals before taking any medicines.Histamines are released when your body defends against attack.If you have an allergy, your immune system treats the allergen as an invader.Histamine release causes inflammation characterized by expansion of small blood vessels and swelling of surrounding skin or tissues.Antihistamines block the effects of histamine and thus relieve symptoms of allergy.