CAUSED hair loss
I used the hair serum as directed on my slightly thinning hair and at first was delighted to notice less hair loss. Then all of a sudden (after about 5 weeks use) I lost a lot of hair all at once which was very upsetting because the hair loss was visible. I stopped using it immediately and 2 months later I have visible hair regrowth (spiky after washing my hair on top of my scalp), so thankfully the hair I lost is growing back. There are no listed side effects for hair loss so I assume this is not normal.