What is the ruling on a pharmacist who sells women's cosmetics,
bearing in mind that most of those who use them are women adorning themselves for other than their husbands and disobeying Allah and His Messenger (peace be upon him), may Allah save us?
If the reality is as you have mentioned, it is not permissible to sell them cosmetics as long as he knows what they do. This falls under helping one another in sin and transgression, which is forbidden by Allah (Exalted be He) in the Qur'an:
...but do not help one another in sin and transgression.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.