It all depends on the indication for which you are using the medication. Logically using it for a few weeks should not be an issue other than contact dermatitis which the person can develop. A certain patch of hair loss on the cheeks may respond to it but if it is diffuse it may not work. I recommend to see a Dermatologist for diagnosis and treatment. There may be better and faster alternatives to what you are presently using. The time taken to respond is usually a a couple of weeks for alopecia areata.