For how long after hair transplant should one use minoxidil spray, and is it beneficial?

It is not mandatory to use minoxidil after a hair transplant in all cases.  Sometimes your hair transplant doctor recommend that due to the high levels of miniaturization (fineness of hair shaft in microscopic evaluation) that may predict more hair loss immediately after and due to the stress of hair transplant (shock loss).That is mostly to prevent your native hair to fall in an accelerate rate after hair transplant.  Finasteride is a better medication that helps to minimize shock loss in men.  However, for women I recommend minoxidil (Rogaine) after hair transplant.You can scratch your scalp after the first 5 days from your hair transplant.

Not all hair transplant surgeons advise minoxidil in the post op period so check with your surgeon for specific advice. The timing of post-op vigorous washing of scabs also varies in terms of recommendations given. Follow the advice of your surgeon.