Allergy in children — symptoms, diagnosis and treatment
Allergies are among the most common chronic conditions affecting children in Denmark. According to the Danish Paediatric Society, around 15–25% of children suffer from allergic hay fever (allergic rhinoconjunctivitis), and 6–8% develop food allergies during the first years of life. In children, allergies can manifest in many ways—such as hay fever, eczema, asthma, food allergies, or reactions to house dust mites and animal dander. Symptoms vary greatly from child to child, and some children experience multiple allergic conditions at once.
Symptoms of Allergies in Children
Allergy symptoms in children depend on the type of allergy and the organs affected. The most common symptoms parents notice are a runny or blocked nose, sneezing, itchy and watery eyes, skin reactions, and gastrointestinal issues.
Respiratory allergies—such as those to pollen, house dust mites, or animal dander—typically affect the nose and eyes, and can trigger or worsen asthma. Hay fever is the most common form, affecting many children from the age of 3 to 5, though symptoms can appear even earlier.
Food allergies primarily cause gastrointestinal symptoms such as vomiting, stomach pain, and diarrhoea, but they can also trigger skin rashes, hives, and, in rare cases, a severe anaphylactic reaction. The most common food allergens in children are milk, eggs, peanuts, tree nuts, wheat, fish, and shellfish.
Skin allergies typically manifest as eczema—causing red, dry, and itchy skin—or as hives, which present as itchy, pale red bumps. Atopic eczema is particularly common in infants and young children and is frequently associated with other allergic conditions.
Causes of Allergies in Children
An allergy occurs when the immune system mistakenly reacts to a normally harmless substance, known as an allergen. Upon first contact, the immune system becomes sensitised without causing symptoms. During subsequent exposure, the body mounts an allergic reaction.
Genetics play a significant role. If both parents have allergies, the risk of the child developing them is up to 60–80%. If only one parent is affected, the risk is approximately 30–40%. Environmental factors, including early exposure to allergens, air pollution, and infancy infections, also influence this risk.
The atopic triad—asthma, allergic rhinitis, and atopic eczema—frequently occur together. Many children develop eczema in infancy and subsequently go on to experience respiratory allergies and asthma, a progression known as the "atopic march".
Examination and Diagnostics
Evaluating a child for allergies begins with a thorough discussion regarding their symptoms, when they occur, and what seems to trigger them. This medical history provides vital clues about which specific allergens should be tested.
Allergy testing is generally conducted in two ways: skin prick testing and specific blood tests. During a skin prick test, a tiny amount of allergen extract is applied to the skin, typically on the forearm, which is then lightly pricked. Localised swelling after 15–20 minutes indicates sensitisation. Blood tests measure the level of allergen-specific antibodies (IgE) in the blood; these can be performed at any age and do not require the child to stop taking antihistamines beforehand.
The choice of testing is always an individual medical assessment based on what is most appropriate for the child. A positive test result must always be interpreted alongside the child's actual symptoms, as sensitisation does not automatically mean a clinical allergy is present.
Treatment of Allergies in Children
Treatment depends on the type and severity of the allergy and is always tailored to the individual child. Generally, there are three primary strategies: allergen avoidance, symptom-relief medication, and immunotherapy.
Avoidance is the most effective approach but is not always practical—particularly for pollen and dust mite allergies. Symptomatic medications, such as antihistamines, nasal sprays, and eye drops, alleviate symptoms but do not treat the underlying sensitisation.
Immunotherapy (often called allergy shots or drops) is the only treatment that alters the immune response itself, offering long-term relief after the course is completed. This treatment is suitable for moderate to severe respiratory allergies and is administered via injections or sublingual (under-the-tongue) tablets or drops.
For food allergies, the primary approach is strict avoidance of the trigger food, combined with an emergency action plan for accidental exposure. Children at risk of severe reactions should always have an adrenaline auto-injector (such as an EpiPen) available.
When Should You Seek Medical Attention?
If your child suffers from recurring symptoms affecting their nose, eyes, or skin that you suspect are due to allergies, it is important to have them examined. This is especially vital if the symptoms disrupt the child’s sleep, general well-being, or ability to participate in everyday activities.
Seek immediate medical attention or go to the nearest emergency department if your child shows signs of a severe allergic reaction (anaphylaxis), such as rapid swelling of the lips, tongue, or throat, breathing difficulties, or fainting.
Allergy Care for Children at Charlottenlund Private Hospital
At Charlottenlund Private Hospital, our specialist paediatrician provides a systematic and thorough evaluation of allergies in children. We conduct a comprehensive assessment of your child's symptoms and medical history, offering tailored skin prick tests and specific blood tests based on their individual needs.
If a child requires a comprehensive assessment for a combination of allergies, asthma, or eczema, we collaborate closely across our hospital departments. For children with respiratory allergies who may benefit from allergy immunotherapy, we provide seamless referrals to dedicated allergy specialists.
Our hospital is located in Charlottenlund, just north of Copenhagen, making it easily accessible from across Copenhagen and North Zealand.
Experience and Expertise at Charlottenlund Private Hospital
At Charlottenlund Private Hospital, paediatric allergies are investigated by leading specialists in paediatrics. Allergy testing, including skin prick tests and specific IgE blood tests, is integrated based on individual assessments. Furthermore, care pathways can be organised multidisciplinary if allergies present alongside asthma or eczema. You can find an overview of all our medical specialties on our department page.
Sources:
Danish Paediatric Society: Allergy assessment of children and adolescents – nationwide clinical guideline
Frequently Asked Questions
When can children get allergies?
Allergy can occur at any age, but often debuts early in childhood. Atopic eczema is frequently seen in infancy, while respiratory allergies and hay fever typically debut from the age of 3-5 and up.
Can children grow out of allergies?
Some children experience symptoms that decrease with age — especially milk and egg allergies in infants often disappear before school age. Respiratory allergies and peanut allergies are more persistent. It is not possible to predict the individual course.
What is the difference between allergy and intolerance?
Allergy involves the immune system and can rarely cause serious reactions. Intolerance — such as lactose intolerance — is a non-immunological reaction that typically causes gastrointestinal symptoms but is not life-threatening.
Can a 2 year old child have allergies?
Yes. Allergies can occur early in life. Milk and egg allergies are common in infants, and eczema often debuts in the first year of life. Respiratory allergies are rarer under two years of age but do occur.
What is the atopic march?
The atopic march describes the typical progression of allergic diseases in childhood — from eczema in infancy to respiratory allergies and asthma in school-age children. Not all children go through all stages, but the pattern is well documented.
Is allergy vaccination possible for children?
Yes. Allergy vaccination — immunotherapy — can be given to children from around the age of five for moderate to severe respiratory allergies. The treatment requires a thorough assessment and is given over a period of several years.
What are the most common allergens in Danish children?
The most common respiratory allergens are grass pollen, birch pollen, house dust mites, and cat and dog hair. The most common food allergens in children are cow's milk, eggs, peanuts, tree nuts, wheat, fish, and shellfish.
Can allergies cause asthma?
Yes. Allergies — especially to house dust mites, pollen, and animal dander — are a common cause of asthma in children. Many children with allergic asthma also have hay fever or eczema. Diagnosis and treatment of allergies can have a positive effect on asthma symptoms.
What is anaphylaxis?
Anaphylaxis is a severe, systemic allergic reaction that can be life-threatening. Symptoms occur rapidly and may include swelling of the throat and tongue, shortness of breath, a drop in blood pressure, and loss of consciousness. Treated urgently with adrenaline.
Does my child need a referral to be tested for allergies?
It is not a requirement to have a referral from your GP to book an appointment with us. If your child has health insurance, we recommend that you check the insurance terms and conditions, as many insurance companies require a referral to cover the treatment.
Read also about
- Asthma in children
- Childhood eczema (atopic dermatitis)
- Food allergies in children