Allergy

An allergy is a condition where the immune system reacts to normally harmless substances as if they were a threat. The immune system's response can range from mild symptoms, such as a runny nose or itchy eyes, to more severe reactions, like a drop in blood pressure, shock, or cardiac arrest.

The exact causes are not fully understood, but genetics, hygiene, and lifestyle play key roles. While the tendency to develop allergies can be inherited, the specific allergen causing the reaction may differ between family members. The likelihood of developing allergies increases with the number of affected relatives. Environmental factors also contribute, with children in developed countries being more prone to allergies, possibly due to a lack of immune system training in overly hygienic environments. Other lifestyle differences, such as diet and urban living, also appear to influence allergy prevalence.

Common allergies include: 

• Hay fever: Triggered by inhaling pollen from trees, grasses, or plants. It affects 10-20% of people in Western countries. 
• House dust mite allergy: Caused by an allergy to the feces of tiny mites that live in bedding and feed on skin flakes. 
• Allergic asthma: Unlike 'normal' asthma, allergic asthma is triggered by allergens like pollen, dust mites, or food. 
• Pet allergy: Allergic reactions are usually to skin flakes, urine, or saliva rather than the pet's hair. 
• Contact allergy: Caused by substances that touch the skin, such as latex, nickel, fragrances, or certain chemicals, leading to eczema or bumps. 
• Food allergy: Often triggered by proteins in foods like milk, peanuts, nuts, fish, and eggs. It's distinct from food intolerance, which is typically related to digestive issues. 
• Insect venom allergy: Can be serious, with reactions to stings from bees or wasps potentially causing anaphylactic shock. 
• Sun allergy: Causes itching or bumps after brief sun exposure, especially in women. 
• Medication allergy: Certain drugs, like penicillin, can provoke allergic reactions. 

Symptoms often appear soon after exposure to allergens and can vary widely. Allergies can be identified by temporarily avoiding suspected allergens to see if symptoms improve. Patch tests may help detect contact allergies by exposing the skin to potential allergens.

The best approach is to avoid allergens, but there are other options, such as using antihistamine tablets, nasal sprays, or eye drops for conditions like hay fever. Making lifestyle adjustments can also help reduce exposure.

For allergic rhinitis, doctors usually recommend avoiding allergen triggers as a first step. A combination of strategies is often needed to manage symptoms. Medication such as non-sedating antihistamines or corticosteroid nasal sprays may be prescribed based on symptom severity. Immunotherapy, a longer-term treatment that reduces hypersensitivity to allergens, can be considered if symptoms persist. This treatment is done under medical supervision and lasts 3-5 years.  

Various tablets, nasal sprays, and eye drops are available to alleviate allergy symptoms. For allergic asthma, inhalable medications can help relax respiratory muscles and relieve symptoms. In cases of severe reactions, such as to insect stings, adrenaline may be administered via an autoinjector. Contact allergies are often treated with corticosteroid creams, while medication allergies may require discontinuing the offending drug. 

Alternative approaches include: 

• Homeopathy: Can potentially alleviate hay fever symptoms. 
• Light therapy: Uses specific light wavelengths to reduce allergic reactions, particularly for hay fever or eczema. 
• Sun allergy prevention: Gradual exposure to sunlight and using quality sunscreen can help prevent reactions. 

To manage allergy symptoms: 

• For pollen allergies: Keep windows closed and limit time spent outside during peak pollen seasons. 
• For dust mite allergies: Regularly air bedding, vacuum mattresses weekly, and avoid making the bed immediately after getting up. Choose synthetic materials, avoid carpets, and ensure good ventilation in bathrooms and kitchens. 
• For pet allergies: The most effective solution is often to remove the pet from the home and avoid contact with the species. 
• For food allergies: Avoiding the allergenic food is crucial, but not always easy. Proteins causing the allergy may be present in various products, and cooking often reduces allergenicity. In cases of serious reactions, strict avoidance is necessary. 
• For contact allergies: Once the allergen is identified, avoid exposure. 
• For allergic asthma: Follow similar guidelines as for pollen, dust mite, and pet allergies. Using hypoallergenic bedding and staying away from smoke can also help. 

Allergology Laboratory Copenhagen (z.j.), All about allergy, consulted on 25 April 2019, at https://allesoverallergie.nl/algemeen 

Gezondheidsplein (2016), How do you get an allergy?, consulted on 25 April 2019, at https://www.gezondheidsplein.nl/dossiers/allergieen/hoe-krijg-je-een-allergie/item42732 

Dutch Care Institute (z.j.) Allergic rhinitis, consulted on 25 April 2019, at https://www.farmacotherapeutischkompas.nl/bladeren/indicatieteksten/allergische_rinitis 

Dutch Care Institute (z.j.) allergen extract grass pollen (parenteral), consulted on 25 April 2019, at https://www.farmacotherapeutischkompas.nl/bladeren/preparaatteksten/a/allergeenextract_graspollen__parenteraal_

Vereniging voor Mensen met Constitutioneel Eczeem (2018), light therapy, consulted on 26 April 2019, at https://www.vmce.nl/eczeem/behandeling/lichttherapie.html