Can minoxidil be tested on one part of the head before using it on the entire head?

Yes, minoxidil will work wherever you use it, so you can start by using it on only a part of the head. Usually a combination approach is best. I suggest seeing a hair loss expert 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 which work well with Minoxidil and/or hair transplantation. See an expert. Best, Dr. Emer

Theoretically you can apply it to a narrow spot but practically I think unless the test spot is quite large, this is a futile exercise. If a little shed, how would you know? Minoxidil is a liquid and will move. Consider parting your dry hair down the middle, and applying to one side. Let dry several hours. Twice/day for 4 months. Let us know the results.

  
Yes, you can test a small area of
the scalp with minoxidil (Rogaine).  You
would need to use it daily for 3-4 months before making a decision on whether
it is working.

Minoxidil is a topical medication that works in the area you place it. So the simple answer to your questions is yes