Minoxidil contains alcohol (synthetic), also we r not consuming, just applying. So, is it allowed? Some people say that because it is synthetic alcohol which is made by chemical, not natural alcohol, so it is OK. Also, we are not consuming, we are just applying on body, so it is fine. Other people say that even though it is synthetic and we are just applying, still it is haraam, and also by trying to modify your looks by doing this, you are Nauzubillah challenging Allah that I do not like the way you have made me and I am changing it. So it is not allowed. Can you please let us know whether this is allowed or no?
Alcohol was once used to sanitise and cleanse an area of the arm before using a hypodermic needle there.
It's less often used that way. This is no way is against Islam as the patient is not being asked to drink it. It's merely being used for the purposes for hygiene.
Similarly for the situation you have outlined.