I am having urticaria for past 4 years.i am completely irritated.tried too many medications but not satisfied.what could be the reason?

Urticaria: Numerous controlled studies as well as case reports have demonstrated that Omalizumab can be employed successfully in approximately 75 % of patients with chronic spontaneous urticaria, leading to a dramatic decrement in symptoms with very few side effects. No other drug currently available is comparable, and the success rate in patients resistant to antihistamines is no different.

Several options: There are many possibilities--i would recommend seeing your physician for detailed bloodwork.