Which of the following antihistamines has the longest half-life?

Hydroxyzine is known to have a longer half-life compared to other antihistamines listed. Typically, the half-life of hydroxyzine ranges from about 20 to 25 hours, which allows for prolonged action in the body. This characteristic makes it effective for managing symptoms over an extended period, particularly in treating allergic reactions and anxiety.

In contrast, loratadine generally has a half-life of about 8 hours, cetirizine around 8 to 9 hours, and fexofenadine approximately 14 to 16 hours. While these antihistamines are effective in their own right, their shorter half-lives mean they might require more frequent dosing for sustained effect compared to hydroxyzine. This is a crucial factor when considering treatment plans for patients who may benefit from longer-lasting relief from allergy symptoms or anxiety.