Definition of the ‘common cold’

Often referred to as ‘hayfever’, ‘nasal allergies’ or even just ‘sinus’, this condition has some similarities to colds and flu. Inflammation in the nasal passages results in the production of mucous which leads to symptoms like a runny, blocked nose and sneezing that are common to the all three conditions. There are also some important differences. Viruses cause colds and flu’, whilst allergens result in the inflammation responsible for allergy symptoms. People suffer from cold and flu symptoms only during the period that they are infected by a virus, whereas allergy sufferers may experience symptoms seasonally or all year round depending on the allergen to which they are sensitive.

People may be allergic to a variety of molecules or substances that can enter the body in different ways. Allergens may be breathed in and enter the the respiratory tract, they may enter via the skin through contact or injection, or they may enter the gastrointestinal tract through eating and drinking. Typical aeroallergens (that cause allergic rhinitis) include house dust mites, grass and tree pollen, moulds, cockroach and animal dander. Common food allergens include eggs, tree nuts, peanuts, soy, fish and cow’s milk. Insect venom, medications and chemicals may also cause hypersensitivity reactions.