I want to mix Minoxidil 5% with caster oil and coconut oil for hair growth. Is this safe and will it work?

Castor oil or coconut oil would not "hurt" but it is not used to treat hair loss.  If you are concerned ask your doctor.

legitpauls,Why would you want to do this? Are you a registered pharmacist? Minoxidil 5% is proven to have benefit in the treatment of genetic hair loss, but I do not know of any studies on Caster, and/or coconut oils! All the best,Bernardino A. Arocha, MD

If you are a male, you might try other treatments,but  if female, will work temporarily. You may want to hormone test as that is one of the reasons for female hair loss. Stress also plays a factor.See a local endocrine specialist first before investing in short term esults.

Your first statement is correct - that minoxidil has a proven positive effect on growth. However, castor oil and coconut oil do not have proven benefit.Mixing anything in minoxidil dilutes it - and makes it potentially less beneficial. But what readers may not be aware is that preparing and heating minoxidil is a nightmare - and can significantly alter the minoxidil and change how it works. Only an experienced pharmacist should be heating minoxidil. In fact, I only trust certain pharmacists when it comes to compounding. It's not easy to mix up minoxidil.   

I don't know why you would want to do this. Who is telling you that this is valuable?  Stick to the minoxidil alone