In which type of hypersensitivity reaction are urticaria and hives typically seen?

The correct answer is Type 1 hypersensitivity reaction. This type of hypersensitivity is characterized primarily by an immediate allergic response mediated by immunoglobulin E (IgE) antibodies. When an individual who is sensitized to a specific allergen is subsequently exposed to that allergen, the binding of the allergen to IgE on the surface of mast cells and basophils triggers the release of various inflammatory mediators, including histamine.

Histamine plays a crucial role in the development of urticaria (hives), which manifests as raised, itchy wheals on the skin. These wheals result from the increased permeability of blood vessels leading to fluid leakage into the surrounding tissues. Additionally, the rapid onset of symptoms following exposure to allergens such as pollen, certain foods, or insect stings aligns with the immediate nature of Type 1 hypersensitivity reactions.

In summary, urticaria and hives commonly present in Type 1 hypersensitivity reactions due to the IgE-mediated release of histamine and other related inflammatory mediators.