This is absolutely a great stimulant for hair growth, not only eyebrow, but scalp as well. However there is a trick to it. Use a needle roller that is no longer than 1mm and use only low to moderate pressure. If you see tincture of blood, you are going too deep. The science behind it involves stimulation of keratinocyte stimulating factor which resides in the top nonvascular layer of the skin. The message signal then travels to lower part of the skin where it can communicate with the milieu of secondary messenger to promote follicular growth. You can use vitamin c, minoxidil, vitamin e oil on the skin prior to needle rolling. Once you needle roll, it will also help with the absorbability of the elements into the skin as well.