Allergic reaction

Allergic reaction is a hypersensitive response of the immune system to a substance (allergen) that is typically harmless to most people. These reactions can range from mild to severe and can affect various parts of the body.

Causes

Allergic reactions occur when the immune system mistakenly identifies a harmless substance as a threat. Common allergens include pollen, dust mites, animal dander, certain foods, insect stings, and medications. When exposed to an allergen, the immune system produces immunoglobulin E (IgE) antibodies, which trigger the release of chemicals such as histamine.

Symptoms

Symptoms of an allergic reaction can vary depending on the allergen and the individual's sensitivity. Common symptoms include:

• Sneezing
• Itching
• Rash
• Hives
• Swelling (angioedema)
• Runny nose (rhinitis)
• Watery eyes
• Shortness of breath
• Anaphylaxis (a severe, potentially life-threatening reaction)

Diagnosis

Diagnosis of an allergic reaction typically involves a combination of medical history, physical examination, and diagnostic tests. Common tests include:

• Skin prick test
• Blood test (such as the RAST test)
• Elimination diet (for food allergies)

Treatment

Treatment for allergic reactions depends on the severity of the symptoms. Common treatments include:

• Antihistamines to reduce symptoms
• Corticosteroids to reduce inflammation
• Decongestants for nasal congestion
• Epinephrine (adrenaline) for severe reactions such as anaphylaxis
• Allergen immunotherapy (allergy shots) for long-term management

Prevention

Preventing allergic reactions involves avoiding known allergens and taking preventive measures. Strategies include:

• Keeping living areas clean to reduce exposure to dust mites and animal dander
• Using air purifiers to reduce airborne allergens
• Reading food labels carefully to avoid allergens
• Wearing medical alert bracelets for severe allergies

See also

• Allergy
• Anaphylaxis
• Histamine
• Immune system
• Immunoglobulin E
• Antihistamine
• Corticosteroid
• Epinephrine