Allergies occur when the immune system reacts excessively to harmless substances such as pollen, dust mites, or certain foods. This reaction causes symptoms such as sneezing, itching, and skin rashes.
Allergies are a bit of a bug in the immune system: instead of ignoring harmless substances like pollen, pet hair, or certain foods, it decides to panic and treat them as dangerous. As a result, it triggers the whole defense arsenal unnecessarily. The body then releases chemical substances, especially histamine, causing itching, swelling, redness, and all those unpleasant sensations that characterize allergies. In other words, the immune system picks the wrong fight, and you end up suffering.
Allergies are often a family affair: if your parents suffer from them, you are clearly more likely to develop them yourself. This genetic factor means that some people are born more sensitive to allergens than others. But that's not all! Your environment also plays a really important role. Being surrounded by excessive hygiene during childhood could limit exposure to certain essential microbes, which then causes your immune system to become overly reactive to normally harmless substances. Pollution, tobacco, and city living—basically everything you breathe in daily—also influence your risk of developing allergies. Even what you eat as a kid and how you live can make a difference. In short, allergies are the result of a not-so-nice cocktail of what your parents have given you genetically and what your daily environment offers you.
Your body comes into contact with a common substance (pollen, peanuts, dust...) and instead of staying calm, your immune system starts to stress unnecessarily. This first encounter is what we call the sensitization phase: your immune cells mistakenly decide that this harmless substance is a real threat. They then produce a series of specific antibodies called IgE, which are tasked with specifically recognizing this imaginary intruder.
During a subsequent exposure to the same substance (allergen), these already present IgE antibodies activate immediately, binding to cells called mast cells, which then release powerful chemicals like histamine. It is the culprit responsible for unpleasant allergic symptoms: runny nose, sneezing, itching, redness, or swelling.
In short, your immune system makes a big deal out of it because it mistakes a harmless substance for a super dangerous threat.
Among the usual culprits are pollens, those from trees, grasses, or herbs, often responsible for the infamous hay fever in spring. On the animal side, common offenders include the fur or dander of our furry friends like cats, dogs, rabbits, or horses. The dust mites found in household dust love to nest in our mattresses and carpets, triggering repeated sneezing. In terms of food, certain items like peanuts, nuts, milk, eggs, fish, or seafood also rank high among known allergens. Not to mention insect stings, such as those from bees or wasps, which can trigger a sometimes very serious allergic reaction. Finally, certain products or chemical substances like latex, perfumes, or preservatives found in cosmetics and shampoos are regularly involved in these unpleasant reactions as well.
First of all, the simplest thing: avoid encountering the responsible allergens. Are you allergic to dust mites? Then you clean your home regularly, use dust mite covers on your bed, in short, you limit the damage. The same goes for pollen: during peak season, you stay indoors as much as possible, with windows closed, especially if it’s windy and blowing all of that around. When it comes to food, if you have a food allergy, then logically, you check food labels and be careful in restaurants.
Next, regarding medication, you have the classic antihistamines, which calm annoying reactions like sneezing, itchy nose, or red eyes. When it gets serious and threatens your life, like in a severe reaction called anaphylaxis, then it’s a direct adrenaline injection and emergency services afterward.
Finally, a long-term solution to consider: desensitization (or specific immunotherapy). Basically, for several years, you are injected with or given the allergen under your tongue, in very small doses that are gradually increased, so that your body can learn to stop panicking for no reason.
Milk, eggs, soy, fish, shellfish, peanuts, tree nuts, and wheat are responsible for more than 90% of food allergy reactions worldwide.
Cross-reactive allergies exist: for example, a person allergic to birch pollen may also experience itching when eating certain apples or hazelnuts, as these foods contain proteins similar to those found in the pollen.
The pollen responsible for your seasonal allergy can vary depending on flowering periods and your region: there are dedicated apps that allow you to track pollen levels in real-time in your environment.
Food and respiratory allergies are not the only known forms of allergies. Did you know that some people are allergic to the sun (allergic photosensitivity) or even to cold (cold urticaria)?
To accurately identify the responsible allergen, it is recommended to undergo allergy tests with a healthcare professional (allergist). These may include skin tests (prick tests), specific blood tests, or elimination-reintroduction tests under medical supervision.
An allergy involves a specific immune response that typically leads to rapid symptoms such as swelling, itching, or breathing difficulties. In contrast, an intolerance does not involve the immune system and is more likely to manifest as digestive issues, cramps, or bloating, usually in a more gradual and less dangerous manner.
Yes, it is entirely possible to develop allergies in adulthood. Although most allergies begin in childhood, sensitizations can occur at any age due to repeated exposure to an allergen, environmental changes, or a late dysregulation of the immune system.
Some allergies, particularly food allergies, are more common in children and may naturally disappear as they grow older. This is due to the gradual maturation of the immune system, which becomes more tolerant of substances that were previously considered threatening.
Yes, several factors can promote the development of allergies, such as family history (genetic factors), early or intense exposure to allergens, air pollution, passive smoking, and decreased contact with certain bacteria during childhood, which is known as the hygiene hypothesis.
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