Is Finpecia good for a woman at the age of 20?

Finpecia is a generic brand of Propecia, which is Finasteride.  Finasteride should NOT be used in women of childbearing age.  It can have significant side effects in a male fetus in a pregnant woman. There are many other ways to treat thinning hair.  Please see a Dermatologist or health care professional who specializes in hair.  You have so many other options. 

No, I won't recommend Finasteride in young women. I will suggest you to visit a local hair loss specialist for a complete hair loss and general evaluation to find out your hair loss cause before starting any hair loss treatment.

Finpecia is generally contraindicated in young women. Some dermatologists may use in combination with oral contraceptives but only under specific circumstances and only for some types of hair loss. Otherwise, it is uncommon to use in a 20 year old female. Is is pregnancy category X meaning severe hair would likely come to a baby born to a mother taking Finpecia