Allergic reactions

Allergic Reactions

Allergic reactions (/əˈlɜːrdʒɪk riˈækʃənz/), from the Greek words allergos (meaning "other work") and reaction (from the Latin re- "back" and actio "a doing, a driving"), are hypersensitivity responses of the immune system to typically harmless substances in the environment. These substances, known as allergens, can include certain foods, pollen, or pet dander.

Types of Allergic Reactions

There are four types of hypersensitivity reactions, which are classified as Type I, II, III, and IV. Type I hypersensitivity is also known as an immediate or anaphylactic reaction and is the type of allergy most people are familiar with.

Type I - This is an immediate reaction, often severe. Common allergens include bee stings, peanuts, and certain medications.
Type II - This type involves specific antibodies called IgG and IgM. It can lead to conditions like hemolytic anemia and thrombocytopenia.
Type III - This type involves immune complex-mediated hypersensitivity. It can lead to conditions like serum sickness and Arthus reaction.
Type IV - This is a delayed hypersensitivity reaction, involving T-cell lymphocytes. It can lead to conditions like contact dermatitis and tuberculosis.

Symptoms

Symptoms of allergic reactions can vary, depending on the type of reaction and the individual's immune response. Common symptoms can include hives, itching, nasal congestion, rash, wheezing, and in severe cases, anaphylaxis.

Treatment

Treatment for allergic reactions typically involves avoiding the allergen, if possible, and managing symptoms. Medications such as antihistamines, corticosteroids, and epinephrine may be used. In some cases, immunotherapy (allergy shots) may be recommended.

Prevention

Prevention strategies can include avoiding known allergens, using air filters to reduce exposure to potential allergens, and maintaining a healthy diet and lifestyle to support the immune system.