Propecia vs Minoxidil for women hair loss?

I have used both extensively and both have distinct benefits and distinct risks. Minoxidil is FDA approved for women with female androgenetic alopecia and helps 30 % of women improve their hair. Side effects include dizziness, heart palpitations, shedding in the first month, hair growth on the face, itching (more with liquid than foam). Other side effects can occur and minoxidil can not be used in pregnancy. It should not be used in those with cardiovascular disease. Finasteride (Propecia) is used more often in post menopausal women than pre-menopausal women on account of concerns for significant harm during pregnancy and women of child bearing ages. It is not formally FDA approved for women but many hair specialists (mostly dermatologists) use off label. It should be prescribed only by a physician with extensive experience in using it for women's hair loss under various conditions. Other hormone blockers used in women include spironolactone, cyproterone acetate (not in USA). I have prescribed finasteride a great deal in post menopausal women and it is very well tolerated. It seems to help about 30-40% of women at 5 mg dosing. In premenopausal women, one needs very carefully discussion and multiple methods of birth control as it causes serious harm to a developing baby if the woman using finasteride were to get pregnant.  Many physicians do not prescribe to premenopausal women for this very reason. Side effects include breast enlargement, breast tenderness, mood changes, depression, anxiety, decreased libido, fatigue and possibly some weight gain.  Concerns about cancer have not been substantiated, but generally one might consider avoiding in women with a very strong history of estrogen dependent cancers (breast, ovarian gynaecological cancers). Side effects are certainly much less common than with minoxidil. Overall finasteride is well tolerated in most women.  More studies are needed to understand the benefits of finasteride in women and how it compares to minoxidil.

Propecia is not licensed for use in women and most doctors would consider the side effect profile to be excessive in women. Minoxidil is very well established and has a much more acceptable side effect profile. Unfortunately, topical minoxidil can be rather an impractical treatment because patients can find it inconvenient and messy to apply. Its longterm compliance in women is therefore often poor. 

This is not a question of which drug you should take. It is a question of what is wrong with you and then after a proper diagnosis is made, getting the right treatment from the right doctor. Genetic hair loss runs in families on the woman's side
(mother, sister, grandmothers etc...), but most female hair loss occurs because
of some underlying cause such as birth control pills, some medications that are
used, and a variety of other diseases that shock the hair into miniaturization.
A typical knowledgeable doctor will examine you, determine the distribution of
your hair loss, see if it is uniform or patchy, take a careful history from you
and order a variety of blood tests to include the following. You must see a
good doctor for this assessment:

Sex Hormone tests

SHBG (Sex Hormone
Binding Globulin) used to test status of male hormones

Estradiol is a sex
hormone

FSH (Follicle
Stimulating Hormone) *not hair follicle but follicle in the ovary*

LH (Luteinizing
Hormone) is a sex hormone

Free Testosterone

Total Testosterone

ANA (Anti Nuclear
Antibody) used to test for Lupus or other autoimmune diseases

TSH (Thyroid
Stimulating Hormone) used to test for hyper or hypo-thyroid disease

Test Iron status

TIBC (Total Iron
Binding Capacity)

Ferritin

Iron