The combination of Zantac (ranitidine) and Zyrtec (cetirizine) helps many people, although you may need to double the regular Zyrtec dose to 10 mg twice a day for decent relief. The Zantac you take should be at least 150 mg twice a day.
In addition to this, some people benefit from 10 to 20 mg of doxepin before bed. Doxepin is an antidepressant when taken at higher doses, but at lower doses acts as a strong antihistamine. It is very sedating however, and some people feel groggy in the morning. Another antihistamine that can be helpful is hydroxyzine, taken at a dosage of 25 mg every six to eight hours if needed, although it is also sedating.