What is the quickest way to treat hives?

Benadryl (diphenhydramine) Benadryl (diphenhydramine). Take 50 mg (two tabs) every 6 hours. Also, take tagamet or another h2 blocker (yes, for the stomach) like Zantac or pepcid. Claritin or another antihistamine will also work in conjunction with benadryl (diphenhydramine). The best addition is prednisone, but this requires a prescription. Your hives should clear in 5 days or so. If they last longer, check in with your doctor.
Hives. Hives: http://www.webmd.com/skin-problems-and-treatments/guide/hives-urticaria-angioedema#1.
Avoidance. Find the trigger and avoid. If not able to find, the next step is oral antihistamines such as claritin, (loratadine) Allegra or zyrtec (non-sedating) during the daytime and benadryl/diphenhydramine at bedtime.