>Not just that, the second generation antihistamines are generally first line for anything where an actual antihistamine would be required,

This is generally true. The exception would be in patients for whom oral medications are not optimal, such as those with nausea and vomiting or with severe allergic reactions -- some 1st generation antihistamines are available in parenteral formulations, whereas, to the best of my knowledge, 2nd generation antihistamines are only available in oral form.