Non-sedating antihistamines, also known as second-generation antihistamines, are medications designed to relieve allergy symptoms with a reduced risk of drowsiness compared to older, first-generation antihistamines. Here's a brief overview:

 * Purpose:

   * They work by blocking histamine, a chemical released by the body during an allergic reaction, which causes symptoms like itching, sneezing, runny nose, and watery eyes.

 * Key Characteristics:

   * Less likely to cause drowsiness.

   * Generally taken once daily.

   * Provide effective relief from allergy symptoms.

 * Common Examples:

   * Cetirizine (Zyrtec)

   * Loratadine (Claritin)

   * Fexofenadine (Allegra)

   * Desloratadine (Clarinex)

   * Levocetirizine (Xyzal)

 * How they work:

   * These medications are less able to cross the blood brain barrier, which is the reason they produce less sedation.

 * Use cases:

   * They are used to treat allergic rhinitis, hives, and other allergic reactions.

It's important to consult with a healthcare professional to determine the most appropriate antihistamine for individual needs.