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world allergy day

July 8 marks World Allergy Day, a joint initiative of the World Health Organization (WHO) and the World Allergy Organization (WAO) to raise awareness of the importance of diagnosing and treating allergic diseases that are increasingly common. .

In this article, we talk about the concept of allergy, its frequency, causes and symptoms.

What is allergy?

An allergy is an immune system disorder that occurs when the body's natural defenses overreact to exposure to a substance (allergen) that is normally harmless (for non-allergic people), treating it as an invasive. This reaction produces chemicals to attack the invader, causing a local inflammatory reaction or generalized symptoms. (1, 2)

Are allergies common? What causes them?

Allergic diseases are very common and have increased in the last 20 to 30 years, affecting about 1 in 4 people in developed countries. These include various conditions that can be caused by different types of allergens: food, drugs, latex, chemicals, insects, pollen, etc.

About 1-5% of the global population has food allergies. More than 120 foods can cause food allergies, but the foods that cause the most common severe allergic reactions are milk, eggs, peanuts, tree nuts, cereals (especially wheat), soy, fish and shellfish. (two)

The allergic reactions

Allergy affects the entire body, and symptoms can arise in the skin and respiratory, digestive and even cardiovascular systems. The severity of symptoms can be very variable, from very mild, which can go unnoticed, to disabling or life-threatening reactions and even death.

Generally speaking, two main types of allergic reactions can occur:
a) immediate, occur in less than 2 hours after exposure to the allergen, being mediated by an antibody called immunoglobulin E (IgE), being usually more serious and of greater risk;
b) late, occurring within 24 to 48 hours after exposure, involving other slower-acting mechanisms of the immune system, being more difficult to diagnose and identify the allergen(s) that give rise to them. (two)

What are the allergy symptoms?

Symptoms caused by allergy can be considered defense mechanisms to protect our body from allergens, which are seen as an aggressor by the immune system. Symptoms also act as an alarm, alerting us that something is wrong. But these defense mechanisms can become harmful to the body itself.

Some of the most frequent symptoms associated with allergic disorders are as follows:
- on the skin and/or mucous membranes: redness, itching, swelling, peeling skin, pimples;
- in the respiratory tract: coughing, sneezing, nasal congestion, breathing noise, chest pressure, difficulty breathing, difficulty swallowing;
- in the gastrointestinal system: abdominal pain, nausea, vomiting, diarrhoea, blood or mucus in the stool;
- on the cardiovascular system: headache, dizziness, low blood pressure, fainting. (2, 3)

Can a person have multiple allergies?

A concept that is closely related to allergy is atopy. Atopy is the tendency of an individual to develop multiple allergic diseases at the same time or over a lifetime.

Cross-reactivity between allergens is also common. For example, allergy sufferers with a pollen or latex allergy may often experience allergic symptoms when they eat certain fruits, vegetables, or nuts. This cross-reactivity occurs because pollen and latex contain proteins similar to proteins in food, and the immune system can react to both. About 70% of food allergies are related to pollen allergy. (two)

Did you know that Fidu products are free from the 14 main allergens, responsible for most food allergies? We do not handle any ingredient in our facilities that may be contaminated with these allergens, thus ensuring that cross-contamination by traces does not occur. That's why our products are safe even for the most sensitive.
Come and discover our products!

IMPORTANT NOTE : The content of this article is merely informative. None of the symptoms mentioned are unique to allergy. Any of them can be caused by other conditions. If you suspect that you have an allergy, seek medical advice.


(1) ACAAI (2014). Food Allergy. American College of Allergy, Asthma & Immunology. Available at:
(2) EAACI (2018). On Allergy. European Academy of Allergy and Clinical Immunology. Available at:
(3) SPAIC Food Allergy Interest Group, 2019. Food Allergy: Concepts and Advice and Precautions, 2nd Edition. Lisbon: Portuguese Society of Allergology and Clinical Immunology with support from Thermo Fisher Scientific and BIAL Laboratories.