Can allergic reaction be caused by using Rogaine cause itching and rash over other parts of your body?

Usually it will occur in the treated area. This needs an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

Typically an allergy to Rogaine occurs only where you have used it.  However, it is possible that if you had it on your hands and touched other parts of your body (like around your eyes) you may have spread it elsewhere.  Much less likely for this to happen on your back, though

Allergies to topical minoxidil is common. Many times it is not the mixoxidil so if you are using the foam switch to the liquid and visa-versa