Allergies are exaggerated responses of the immune system to substances that, in most people, do not cause an adverse reaction. These substances are known as allergens and may include pollens, dust mites, foods, medicines, insects or moulds. People with allergies often experience uncomfortable symptoms such as sneezing, nasal congestion, itching, swelling and, in more severe cases, anaphylactic reactions.
Types of allergies
- Respiratory allergies: These are one of the most common, caused mainly by pollen (seasonal allergic rhinitis), dust mites, moulds and animal dander. Symptoms include sneezing, runny nose, itchy eyes, congestion and, in some cases, allergic asthma, which causes difficulty breathing.
- Food allergies: These occur when the body overreacts to certain foods such as peanuts, tree nuts, shellfish, milk and eggs. Symptoms can range from mild to severe, such as hives, gastrointestinal problems or anaphylaxis, a life-threatening reaction that requires immediate treatment with epinephrine.
- Drug allergies: These occur when the immune system reacts to a drug, such as antibiotics (penicillin) or non-steroidal anti-inflammatory drugs. Symptoms may include rash, swelling, difficulty breathing or anaphylaxis.
- Insect allergies: Stings from insects, such as bees, wasps and ants, can cause severe allergic reactions. Stings usually trigger localised swelling, but in allergic individuals, they can cause generalised reactions, including difficulty breathing and anaphylactic shock.
Diagnosis
Diagnosis of allergies is made through a combination of the patient’s medical history, allergy tests and, in some cases, laboratory tests. Skin tests (prick tests) are the most common, in which small amounts of allergen are applied to the skin to observe the reaction. A blood test may also be performed to measure levels of immunoglobulin E (IgE), an antibody associated with allergic reactions.
Treatment
- Allergen avoidance: The first step in treating allergies is to identify and avoid exposure to allergens. This may involve using air filters, avoiding certain foods or medications, and taking preventive measures in the home, such as dust mite or mould control.
- Medications: Antihistamines are a common class of medications used to control mild to moderate symptoms, such as itching, sneezing and runny nose. In cases of more severe symptoms, such as asthma, inhaled corticosteroids or bronchodilators may be necessary. For severe reactions, such as anaphylaxis, auto-injectable epinephrine is the standard emergency treatment.
- Immunotherapy: Also known as desensitisation therapy, this option involves administering increasing doses of the allergen under medical supervision to train the immune system not to overreact. This treatment is often used for respiratory or insect allergies and can significantly reduce symptoms in the long term.
Tips for patients
- Avoid exposure: Keeping windows closed during pollen season and using filtered air conditioning can help reduce exposure to environmental allergens. It is also advisable to avoid contact with animals if you are allergic to pet dander.
- Emergency plan: Patients with severe allergies, especially those at risk of anaphylaxis, should carry an epinephrine auto-injector and have a plan of action that includes early recognition of symptoms and appropriate use of medication.
- Regular medical consultation: It is important that people with allergies are regularly evaluated by an allergist to adjust their treatment and monitor their condition.
Bibliography
- Dykewicz, M. S., & Hamilos, D. L. (2010). **Rhinitis and sinusitis.** Journal of Allergy and Clinical Immunology, 125(2 Suppl 2), S103-S115.
- Sicherer, S. H., & Sampson, H. A. (2014). **Food allergy: Epidemiology, pathogenesis, diagnosis, and treatment.** Journal of Allergy and Clinical Immunology, 133(2), 291-307.
- Boyce, J. A., et al. (2010). **Guidelines for the diagnosis and management of food allergy in the United States.** Journal of Allergy and Clinical Immunology, 126(6), S1-S58.
- Bousquet, J., et al. (2012). **Allergic rhinitis and its impact on asthma (ARIA): Achievements in 10 years and future needs.** Journal of Allergy and Clinical Immunology, 130(5), 1049-1062.
