Rosemary oil blocks DHT, a type of testosterone that shrinks hair follicles and leads to hair loss. What To ConsiderSure, my list of the best rosemary oil hair products for hair growth pulls together the best of the best , but if you find yourself scrolling through comparing one product versus another, here are some shopping pointers to keep in mind. To Achieve Glossy Hair And Reduce BreakageNiacin (vitamin B3), saw palmetto, biotin, and vitamin E are beneficial for hair growth and restore shine to dull hair. How We ChoseExpert-Consulted, Editor-Tested PicksTo help zero in on promising rosemary oil hair growth products, I started by consulting professionals about their suggestions. After testing a few new rosemary products for hair growth, only and have impressed me over the last six weeks.