Hi, Brachioradial pruritus (BRP) is a localized neuropathic change in sensation of the upper extremities. That exact cause is still not completely understood. However, evidence suggests that cervical spine nerve entrapment or neuropathy due to peripheral nerve injury are the causative underlying problem. However, the good news it is a benign and transient problem. If I were your treating doctor first I would ask for cervical MRI to rule out cervical radiculpathy. As treatment, I would advise your fiance to avoid his arms to the sun. Ice packs helps. Also topical anti-pruritic medications help. If gabapentin is not helping studies report that oral tricyclic anti-deprassant could help. Moreover, oral medication such risperidone, fluxetine help. These are not antihistamines as antihistamines dont help in this case. Those aforementioned medications should be taken under medical supervision. For this you need expert s guidance by a neurologist. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Ahmad Nazzal, General & Family Physician