Hi.. Thanks for the query.. As per your complain itchy blisters on arms and leg can be due to causes like CONTACT DERMATITIS that is an allergic reaction which occurs when skin comes in contact with certain agents that your body is allergic to like skin cosmetics, detergents, soaps, fragrances,leather, latex, poison ivy etc.. Other cause can be Hair follicle infection caused by Staphylococcus bacteria leading to formation of painful bumps over different parts of the body.. Scabies can also be a cause.. Consult an Emergency room and get a clinical evaluation and investigations like blood tests to rule out allergies and infection, micorscopic examination of scrapings from lesion can help.. As of now you can take anti allergics like benadryl for relieving itching and do cool compresses over bumps.. Once the cause is ruled out it will be treated accordingly.. - In case of Contact Dermatitis you will be advised anti allergics, topical steroid ointment application and also avoiding exposure to allergen when it is ruled out... In recurring conditions Immunotherapy will be advised to you.. -In case of folliculitis antibiotics oral and topical and topical steroids can be advised along with anti allergics to control itching.. Hope this helps.. Regards.