The lightweight serum is designed to transform hair, making it thicker, fuller, denser, and healthier, thanks to a megamix of clever ingredients, and it seems TikTokers can’t get enough of its hair-boosting properties. Hair thinning is something I have experienced for a while thanks to the hormonal condition polycystic ovary syndrome (PCOS), which causes diminished hair around the hairline and temples. I also straighten my hair daily, so I welcome anything that improves frazzled strands. Admittedly, hair-growth shampoos, conditioners, and treatments haven’t worked well for me, but on hearing so many excellent things about The Ordinary’s serum, I had to try it.