What Are Allergies? Types and Common Symptoms
Discover what allergies are, their main types like food and pollen allergies, symptoms, and causes. Learn how the immune system overreacts to harmless substances in this comprehensive guide for better understanding.
Allergies occur when the immune system overreacts to harmless substances called allergens, such as pollen or pet dander. This exaggerated response can cause symptoms ranging from mild itching to severe life-threatening reactions known as anaphylaxis. Understanding allergies helps in recognizing triggers and managing daily life effectively.
How Allergies Develop
Allergies begin when the body mistakenly identifies a harmless substance as a threat. The immune system produces antibodies called immunoglobulin E (IgE) specific to that allergen. Upon re-exposure, these antibodies trigger the release of chemicals like histamine, leading to inflammation and symptoms. This process, known as sensitization, can develop at any age but often starts in childhood. Genetics and environmental factors play key roles in susceptibility.
Common Types of Allergies
Food Allergies: Triggered by proteins in foods like peanuts, shellfish, or milk. For example, peanut allergies affect about 1-2% of children and can cause rapid swelling or breathing issues.
Pollen Allergies (Hay Fever): Caused by tree, grass, or weed pollen. Seasonal allergies peak in spring and fall, leading to sneezing and itchy eyes, as seen in millions during ragweed season.
Dust Mite Allergies: From tiny mites in household dust. Symptoms worsen in bedding; a common example is perennial rhinitis affecting indoor environments year-round.
Pet Allergies: Reactions to proteins in pet saliva, urine, or dander. Cat allergies are widespread, impacting even non-cat owners through shared spaces.
Insect Sting Allergies: Bee or wasp venom causes localized swelling or systemic reactions. Anaphylaxis from stings hospitalizes thousands annually.
Drug Allergies: Antibiotics like penicillin provoke rashes or hives. Reactions vary from mild skin issues to severe organ involvement.
Symptoms of Allergic Reactions
Symptoms depend on the allergy type and exposure route but commonly include sneezing, runny nose, itchy eyes, and skin rashes. Inhaled allergens often affect the respiratory system, while ingested ones impact the gut or skin. Severe cases involve anaphylaxis, with throat swelling, low blood pressure, and shock requiring immediate epinephrine.
Mild Symptoms: Hives, itching, watery eyes.
Moderate Symptoms: Nasal congestion, coughing, wheezing.
Severe Symptoms: Difficulty breathing, vomiting, dizziness.
Risk Factors and Prevention Tips
Family history increases risk, as do conditions like eczema or asthma. Environmental exposures, such as pollution or early antibiotic use, may contribute. Prevention involves avoiding known triggers, using air purifiers, and washing hands after pet contact. Real-world examples include schools banning peanuts to protect allergic students.
Diagnosis and Everyday Management
Doctors diagnose via skin prick tests, blood tests for IgE, or elimination diets. Management focuses on avoidance and medications like antihistamines. For instance, sublingual immunotherapy has helped pollen allergy sufferers build tolerance over time.