Claritin, as an artifact of the approval process for the drug (due to it being one of the early second generation anti-histamines), does not reccomend a dose which is sufficient to work for most people. Taking 2 can work, but risks drowsiness similar to benedryl and other first generation anti histamines. Claritin is basically designed to barely work when taken as instructed. I reccomend other "second gen" options like Zyrtec or Allegra.