Which stds causes itchy skin hive like rash all over body?

Probably no STD. Syphilis can cause a body-wide rash, but not hive-like and usually not itchy. If you think you're at risk for STDs, get tested. But an STD is not a likely cause of this rash. Most rashes like this are due to drug allergy -- which could include an STD drug if you're on treatment. In that case, contact the doctor treating you. Good luck!