British Medical Journal and The Guardian have an overview on removing unwanted facial hair for women, with a focus on eflornithine:
Sometimes, there’s no obvious cause for unwanted facial hair. It might be inherited, so if your mother or grandmother had a lot of noticeable hair on her face, you might get it too. But there’s also a medical condition, called polycystic ovary syndrome, which can cause more hair to grow on your face.
The newest treatment for facial hair is a cream called eflornithine (brand name Vaniqa). It works to slow down the rate at which hair grows. You need a prescription from your doctor for this cream. You rub a thin layer of cream into your skin twice a day. You shouldn’t wash the areas treated for four hours afterwards.
Full article (guardian.co.uk)