Below are additional sources offering more detailed information on a variety of subjects
Caffeine and hair growth
Caffeine's mechanisms of action and its cosmetic use
A. Herman, A. P. Herman, Skin Pharmacol. Physiol. 2013, 26, 8-14.
Review article on caffeine which given its high bioactivity and main penetration properties is used in a variety of applications for skin and hair care.
Analysis of the penetration of a caffeine containing shampoo into the hair follicles by in vivo laser scanning microscopy
J. Lademann, H. Richter, S. Schanzer, A. Klenk, W. Sterry, A. Patzelt, Laser Physics 2010, 20, 551-556.
This study analysed the penetration and storage of a caffeine-containing shampoo in the hair follicles by in vivo laser scanning microscopy.
Hair growth mechanism, cAMP, testosterone, 5α-DHT, 5α-reductase
Caffeine – stimulant and medicinal substance
K. Nieber, S. Felke, A. Schmalz, Pharm. Ztg. 2007, 4, 16-22.
Review article on caffeine as a natural stimulant and active ingredient.
Influence on the hair cycle, hair growth/hair loss
The hair follicle as a dynamic miniorgan
M. R. Schneider, R. Schmidt-Ullrich, R. Paus, Curr. Biol. 2009, 19, 132-142.
Review article on the structure and biology of the hair follicle.