Antihistamines are a class of medications commonly used in dermatology to alleviate itching, hives, and other allergic reactions. Histamine is a chemical released by the body’s immune system during an allergic reaction, causing itching, swelling, and redness. Antihistamines work by blocking the action of histamine on certain cells in the body, reducing the severity of allergic reactions.

There are two types of antihistamines: first-generation and second-generation. First-generation antihistamines, such as diphenhydramine and hydroxyzine, are known for their sedative effects and can cause drowsiness. Second-generation antihistamines, such as loratadine and cetirizine, are less likely to cause drowsiness and are preferred for daytime use.

In dermatology, antihistamines are often used to treat allergic skin conditions such as urticaria (hives), atopic dermatitis (eczema), and contact dermatitis. They can be taken orally or applied topically in the form of creams or lotions.

This module will provide an overview of the different classes of antihistamines used in dermatology, including their mechanism of action, indications, contraindications, adverse effects, and drug interactions. Both first-generation and second-generation antihistamines will be covered.

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1. Bolognia J, Schaffer JV, Cerroni L. Dermatology. 4th edition ed: Philadelphia, Pa.: Elsevier; 2018 9th November 2017. P. 2880

2. Wolverton SE, Wu JJ. Comprehensive dermatologic drug therapy. 4th edition ed: Philadelphia, PA: Elsevier; 2021 19th March 2020 p.1024