HI - My Mum Who Is 85 Years Old Is

HI - My mum who is 85 years old is an asthmatic. She suddenly developed dark itchy skin and has been to a dermatologist but the medication does not seem to work. She was asked by her GP to do a Blood test - Her easonophil count is very high - The GP has given her a 3 week course of Heterazan - Pls advise if this is the best course