Sneezing and watery eyes, rashes and skin irritation, swelling and itching. These are just some of the most common symptoms of allergies, a condition that affects millions of people throughout the world, especially in developed countries. The immune system does not function properly : it overreacts, attacking foreign substances that normally would not cause any harm. These invaders, called allergens, might include pollen, mould and dust mites, among many other possibilities.

In developed countries, the percentage of the population affected by allergies has increased. One reason for this epidemic of modern times is the obsession with cleanliness. This means that the body, from infancy, is not exposed to enough dirt to train the immune system, which then reacts inappropriately to any foreign substance, no matter how harmless. Upon the first exposure to an allergen, the immune system becomes sensitised. In subsequent exposures, an allergic reaction occurs, which can range from a skin rash to various breathing problems. The reaction varies from person to person .

Best known allergens :

Among all the substances that can produce an allergic reaction, these are the most important :

POLLEN : Minuscule grains released by plants during their reproductive process. They cause hay fever and breathing problems.

DUST MITES : Small insects that live inside the home. They cause allergies and asthma.

WASP STINGS : Some people have an excessive, even deadly, allergic reaction to the sting of a wasp or other insects.

PEANUTS : The allergy to this food is rapidly growing. In a few cases, it can be fatal.

RAGWEED : A type of weed that is one of the main causes of allergies in the United States. It produces intense rhinoconjunctivitis and, more rarely, asthma. Its pollen is very potent and is the cause of the allergic reaction.

Allergies are epidemics of modern times. The more industrialized a country, the greater the affected population. In contrast, in developing regions, the number of people affected is much lower. In remote regions, allergies are almost non-existent.

Rhinitis and asthma, like the other respiratory allergies, increase with the arrival of autumn. They are incapacitating, and they exact an enormous cost in terms of lost work and missed school days. The cold, in turn, irritates the respiratory tract, making it more susceptible to infections, especially viral ones. Changes in the respiratory mucous membranes and the immune system activate or reactivate the allergies. Moreover, the lack of ambient ventilation because of the cold weather and the concentration of indoor allergens, such as mites and fungi, increase and contribute to triggering this disease.