A study published in the journal Molecules in 2013 reported that the key ingredient in Procapil, oleanolic acid, causes liver damage when ingested by mice. According to a study published in 1988, oleanolic acid also causes infertility in rats, but the effect was temporary and went away after use of the substance was stopped. Apigenin, another ingredient of Procapil, was shown to exhibit significant cell toxicity at even very low concentrations in a study published in 2008.
The manufacturer of Procapil states that it has virtually no side effects and has been extensively tested in clinical studies. According to the US patent office and the manufacturer, Procapil contains oleanolic acid, apigenin and biotinyl-GHK. Oleanolic acid inhibits 5-alpha-reductase, the enzyme that converts testosterone to dihydrotestosterone. Apigenin is a vasodilator, and biotinyl-GHK stimulates overall cell metabolism.
Procapil is intended to stop male-pattern baldness from progressing and is also intended to help re-grow hair, according to the manufacturer. It is included in shampoos at a concentration of 2.5 percent that are to be used daily. The oleanolic acid is intended to block the creation of DHT in the hair follicles, stopping the progression of male-pattern baldness. The apigenin is intended to improve blood flow to the hair follicles, nourishing them and supporting growth. The biotinyl-GHK is intended to stimulate the metabolism of the cells in the hair follicle, encouraging growth.