Immune System
Allergies
An overreaction of the immune system to normally harmless substances, causing symptoms that range from mild to severe.
Overview
Allergies occur when the immune system reacts to a substance (an allergen) that is typically harmless to most people. Common allergens include pollen, dust mites, pet dander, certain foods, insect stings and some medications. Reactions can vary widely from person to person and can change over time.
Common Symptoms
- Sneezing and a runny or blocked nose
- Itchy, watery or red eyes
- Skin rashes or hives
- Coughing or wheezing
- Swelling of the lips, face or throat
- Digestive discomfort after certain foods
Possible Causes
- Immune system sensitivity to specific allergens
- Pollen from trees, grasses and weeds
- Dust mites and pet dander
- Foods such as peanuts, tree nuts, shellfish, eggs or milk
- Insect stings and certain medications
Risk Factors
- A family history of allergies or asthma
- Having asthma or eczema
- Environmental exposure to allergens
Diagnosis
Healthcare professionals may review symptoms and exposure history and, when appropriate, use skin-prick or blood tests to help identify specific triggers.
Treatment & Management
Management often focuses on reducing exposure to known triggers and may include antihistamines, nasal sprays, eye drops or, in some cases, allergy shots (immunotherapy) guided by a specialist.
Prevention & Healthy Habits
Limiting exposure to known allergens, keeping indoor air clean, using dust-mite-proof bedding and following a personal action plan can help reduce flare-ups.
When to Seek Medical Care
- Difficulty breathing or swallowing
- Swelling of the face, lips or throat
- Feeling faint or rapid heartbeat after exposure
- Symptoms that disrupt daily life or sleep
Questions to Ask Your Doctor
- What am I most likely allergic to?
- What treatments are appropriate for me?
- How can I reduce exposure at home?
- What signs mean I need urgent care?
Related Topics
Related Symptoms
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