"...Topically applied azelaic acid has been proven to be the most effective inhibitor of DHT synthesis in the scalp. A topical 5% azelaic acid solution will reduce the amount of DHT in the scalp by greater than 98%. Xandrox incorporates 5% azelaic acid and 5% minoxidil, so that there is promotion of hair growth as well as prevention of atrophy of the hair follicles. The 5% azelaic acid in all of the Xandrox formulations is approximately 3 times the concentration necessary to obtain essentially complete inhibition of DHT synthesis.
When azelaic acid is initially used, it may cause a temporary stinging or burning sensation. There are no harmful direct or side effects to the use of azelaic acid."
I have a 15% azelaic acid lotion I used to use on my face, but don't need to use it anymore, and there is still some left over, I wonder if it would be ok to apply to the scalp?