What is the best antihistamine for runny nose?

new generation: The new generation antihistamines (zyrtec, claritin, allegra) are as effective as traditional antihistamines such as Benadryl (diphenhydramine) but have less side effects and longer duration of action. They come in several forms and are available with or without the decongestant pseudoephedrine. Sometimes it helps to try more than one of the new generation products and see which works best for each person.