Hello~ This serum I used only about 6 drops from, it irritated my skin because I am super sensitive. I purchased for $150 and missed the return window, so just trying to get some of my money back. you can read about it online here: https://www.skinceuticals.com/skincare/anti-aging-serum/p-tiox-anti-wrinkle-serum/S123.html?GeoRedirectOff=null&gad_source=1&gbraid=0AAAAAD-M-Ec7ajWpnC04utt8g3DgvwOIs&gclid=Cj0KCQjwh7K1BhCZARIsAKOrVqHRCezTjqNBiMG0ycagQ6bXF7RJvQawlAGRm4ts4ElD5XAtcZfaco4aAoUkEALw_wcB&gclsrc=aw.ds