Causes of Allergies in Children

In most instances of allergic reactions, the immune system is at the core of the issue. Normally, the immune system combats foreign and harmful entities such as bacteria and viruses. However, in the case of allergies, the immune system overreacts violently to a substance that is typically non-harmful—like the examples previously mentioned. This exaggerated response is triggered only in children with allergies, whereby the body identifies allergens as harmful substances and mounts an attack using antibodies known as Immunoglobulin E (IgE). These antibodies bind to specialized cells known as mast cells, prompting the release of histamine and other chemical compounds when the allergens attach to the antibodies. The visible symptoms in children can vary according to the type of tissue that is irritated. For instance, irritation of nasal tissues may lead to allergic rhinitis symptoms, while respiratory allergies may manifest as asthma symptoms such as coughing and wheezing. In more severe cases, the entire body may react strongly to an allergen.

Common Airborne Allergens

Many of the most prevalent allergens are dispersed through the air, and several types can be identified:

Pollen: Scientifically known as hay fever (allergic rhinitis), pollen from trees, grasses, and weeds is the leading cause of seasonal allergies. The timing of allergy symptoms can vary depending on the specific type of pollen to which the child is sensitive.
Dust Mites: These microscopic organisms are not visible to the naked eye and thrive in household dust. They are a common trigger for multiple annual allergy episodes and asthma attacks. Dust mites prefer warm, humid environments, often found in:
- Bed linens, mattresses, and pillows.
- Carpets.
- Upholstered furniture and textiles around the home.
- Stuffed animals.
- Clothing.
Mould: Belonging to the fungal family, mould releases tiny spores into the air that, when inhaled, trigger allergic reactions as a natural response to foreign substances. The severity of mould allergies can vary from child to child. Children are particularly susceptible due to their developing immune systems, making them more prone to chronic allergic reactions, especially if they have asthma. Mould typically thrives in damp and dark areas, both inside and outside the home:
- Outdoors: Mould can be found in shaded, moist areas, compost piles, and decaying leaves.
- Indoors: Common places for mould growth include basements, food storage areas, mattresses, bathrooms, carpets, and air conditioning units.
Pet Dander: Pets can carry dust, plant pollen, and various other allergens in their fur or hair. Children may also develop reactions to proteins present in pet saliva, dander, or urine. Allergens from pets can spread through the air in homes and settle on a child’s skin and eyes, causing allergic reactions. Studies show that bathing pets weekly can significantly reduce allergenic effects from shedding fur, and keeping them outdoors, if possible, is often the best approach. In some cases, pet allergies can also lead to hives and itching.

Food Allergens

Food allergies differ distinctly from food intolerances despite similar symptoms. Food allergies arise when the immune system reacts to a specific food type, while intolerances do not involve the immune response. It is important to note that a child must have been previously exposed to a particular allergen, either through breastfeeding or direct consumption, before developing an allergy. Common food allergens in children include eggs, fish, milk, peanut butter, seafood such as shrimp and crab, along with wheat, soy, and nuts. Notably, milk and peanut allergies are particularly prevalent, with peanut allergies often leading to severe reactions that may persist throughout life. In contrast, allergies to eggs, soy, milk, and wheat typically resolve with age.

Children often manifest allergies to proteins found in cow’s milk and milk formulas containing bovine protein. Milk proteins may also be hidden ingredients in many prepared foods. Allergies to eggs can pose a greater challenge for parents than milk allergies, but in both cases, children usually overcome these allergies over time, unlike allergies to fish, seafood, and nuts, which are more likely to endure throughout life. It is crucial to note that while individuals who are allergic to one type of fish may not be allergic to others, soy allergies are more common in infants and older children. Peanut allergies and tree nuts like almonds and hazelnuts are also increasingly prevalent and may not disappear with age. Wheat allergies, caused by proteins in wheat products, can sometimes be confused with celiac disease, which is a reaction to gluten found in wheat, corn, and barley. However, wheat allergies can have more severe complications than celiac disease and other food allergies, potentially leading to life-threatening situations.

Other Allergens

A plethora of additional allergic triggers exists, including:

Insect stings from bees, wasps, ants, etc., which can cause localized swelling, redness, and itching, with potential serious complications if venom is involved.
Certain medications, including antibiotics, anti-seizure medications, and non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin.
Chemical ingredients in some cosmetics and laundry detergents, which can result in hives from skin reactions. Although this response is generally not classified as an allergy, children can have allergic reactions to other chemical triggers like household cleaners, dyes, and pesticides found on plants.
Skin reactions caused by direct contact with specific substances, known scientifically as contact dermatitis. This dermatitis can arise from various triggers, including:
- Poisons ivy or poison sumac.
- Certain chemicals such as nickel, neomycin, fragrances, and more.

Common Triggers of Anaphylaxis

Anaphylaxis is a severe and rapid allergic reaction that can lead to fatality, necessitating immediate emergency assistance and appropriate care for the child. Pediatricians often prescribe epinephrine as the first-line treatment for anaphylaxis. Parents should keep this medication readily available if their child has previously experienced anaphylaxis or if they have risk factors associated with it. The triggers for anaphylaxis can coincide with other allergy triggers and can stem from insect stings, certain medications, and foods such as eggs, milk, seafood, peanuts, and nuts.

Causes of Allergies in Infants

The causes of allergies in infants closely resemble those in older children, but airborne allergens like pollen, dust mites, and mould are rarely encountered during the first year of life. Instead, infants commonly develop food allergies or atopic dermatitis (eczema), especially in families with a history of eczema, asthma, rhinitis, or other allergies. Eczema flare-ups in newborns can arise from various triggers, including soap, heat, and irritating fabrics. Eczema is one of the most frequent skin disorders observed in newborns, with atopic eczema being the most diagnosed form.

Environmental factors rarely trigger allergies in infants since it typically takes about a year of exposure for an infant to develop an allergic reaction. Nevertheless, some traditional allergy symptoms, such as rashes and nasal congestion, may emerge for reasons still unknown to researchers, although genetics are thought to play a significant role. Food allergies in infants generally begin when they start consuming solid foods, with allergies predominantly involving eggs, milk, seafood, wheat, and nuts being more common in infants than in older children. Many ready-to-eat foods, like formula, contain soy proteins; thus, infants allergic to cow’s milk are often also sensitive to formulas containing soy. Symptoms of milk allergy may appear within days to weeks after the first intake of formula containing bovine protein, and breastfeeding is generally protective against developing this allergy. While milk allergy does not have a specific age limit, infants are particularly vulnerable, and some may outgrow it while others may not.

Diaper rash is common among newborns and children, and its cause is not solely from the diaper itself; it may also arise from sensitivity to dyes in diapers or cleaning agents used for laundering cloth diapers. The causes of contact dermatitis differ between newborns and older children or adults, as infants are usually shielded from environmental allergens, making moisturizing creams and soaps the most common causes for this type of dermatitis in newborns. However, as children grow older, the range of contact dermatitis triggers expands alongside the typical diaper and scented wipes.

Children at Higher Risk for Allergies

Although allergies are more frequently observed in children, they are not exclusive to this age group. Allergies can affect individuals of any age, regardless of gender, ethnicity, or socio-economic conditions. Allergies can emerge at any life stage and can reappear after many years of absence. Family history plays a significant role, as having a parent with a specific allergy increases the likelihood that a child will develop an allergy as well. Therefore, assessing whether either parent has any allergies is beneficial. However, this does not imply that all children will inherit allergies, even if genetic predisposition is present; family members can experience different allergies, and one member may react to a specific allergen that another does not. Furthermore, if a child is allergic to one allergen, their risk of developing additional allergies increases, particularly when combined with various factors such as:

Being born in spring makes a child more susceptible to allergic rhinitis compared to those born in other seasons.
Introducing solid foods or cow’s milk- or soy-based formulas before a child is three to four months old heightens the risk of food allergies or eczema.
Exposure to secondhand tobacco smoke can lead to respiratory allergies.

Theories on the Increasing Prevalence of Allergies in Children

The reasons behind the rise in allergies remain somewhat ambiguous. Many experts suggest that air pollution and excessive cleanliness in homes compared to outdoor environments may weaken children’s immunity, thereby increasing the incidence of allergies. Conversely, some believe that insufficient exposure to harmless microorganisms found on skin, in the gut, and in untreated soil and water contributes to heightened allergy susceptibility. Both theories support the idea that inadequate stimulation of the immune system compromises its ability to resist allergens, resulting in an exaggerated response to non-harmful substances. Other hypotheses propose that dietary changes and vitamin D deficiency might be contributing factors to allergy development. Still, there is no conclusive evidence attributing allergies to a single cause; rather, it is likely a combination of various factors.

Tips for Allergy Prevention in Children

It is advisable to ensure proper ventilation throughout the home, repair any leaks, and eliminate any moisture accumulations to prevent mould growth. The following tips can help reduce dust mites in the home:

Maintain indoor humidity at 50% or lower than outdoor humidity and use dehumidifiers in damp areas of the house.
Cover mattresses and clothing storage with dust-proof covers.
Avoid using down or foam pillows; if necessary, encase them prior to use.
Regularly wash bedding in hot water, as cold water does not eradicate dust mites; stuffed animals can be placed in the freezer to kill them.
Minimize the use of humidifiers.
Avoid wall-to-wall carpeting and clean it regularly.

To mitigate allergic symptoms from pets, consider the following:

Keep pets out of bedrooms and areas where children spend a significant amount of time.
Eliminate all types of carpets or vacuum regularly.
Prevent children from cuddling or kissing pets, if possible.
Encourage thorough handwashing after interacting with pets.

Avoiding allergens is critical for preventing allergies and anaphylactic shocks. If a child has a food allergy, they should be instructed to wash their hands before meals and to avoid sharing food. It is also vital for them to learn how to make safe food choices when dining at school or restaurants. Parents should inform hosts of the child’s allergies when attending parties or playdates and ensure that they know where to find and how to administer the allergy injection when needed. Moreover, tobacco and smoking expose children to increased risks; prenatal and postnatal exposure heightens the likelihood of asthma and wheezing. Conversely, breastfeeding for 4-6 months or using appropriate milk formulas is known to lower the risk of milk allergies and atopic dermatitis, while strengthening the child’s immune system.

Video on Childhood Eczema

To gain more insight into childhood eczema, watch the video.