TLDR Certain natural extracts can promote hair regrowth.
The study investigated the effects of 50% ethanol extracts from 14 crude drugs on hair regrowth in mice with removed abdominal hair. It found that extracts from Polygonum multiflorum (I), Drynaria fortunei (II), Panax japonicum (VII), and Swertia japonica (XI) promoted hair regrowth in normal mice. Additionally, extracts I and VII were effective in mice pretreated with a high butter diet. These findings suggested that extracts I and VII could be used as hair tonics to promote hair regrowth.
January 2022 in “Wiadomości lekarskie (Warsaw Poland)” MSM reduces hair loss and promotes hair growth in male mice.
February 2020 in “The Pharmaceutical Society of Japan” 
April 2018 in “Journal of Investigative Dermatology” Minoxidil didn't significantly increase hair growth in minipigs.
5 citations,
January 2015 in “Journal of clinical & experimental dermatology research” MorrF improves hair growth better than minoxidil alone.
The herbal extract CS-10-H significantly promotes hair growth in mice.
56 citations,
April 2007 in “Journal der Deutschen Dermatologischen Gesellschaft” Minoxidil works better for female hair loss than alfatradiol, both safe.
January 2007 in “Strait Pharmaceutical Journal” 
1 citations,
September 2002 in “PubMed” Minoxidil helps stimulate hair growth and reduce hair loss in women with androgenic alopecia.
July 1995 in “Journal of Dermatological Science” Cyclosporine starts hair growth faster, while minoxidil makes it last longer.
