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.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.If you have an allergy, your immune system treats the allergen as an invader.
They are classified as first generation (sedating) and second generation (non-sedating) antihistamines.
Antihistamines block the effects of histamine and thus relieve symptoms of allergy.
Oral antihistamines are used for the treatment of a number of allergies, including allergic rhinitis in which they reduce runny nose and sneezing but are usually less effective for nasal congestion.
They are also used to treat urticarial rash (hives), itchy skin and eyes (eczema and conjuctivitis).
They are also of some value in preventing hives and in treating drug allergies.