These medications block the production of estrogen, thereby stimulating the pituitary to increase production of LH and FSH, which in turn induces ovulation. Though only approved in the U.S. to prevent recurrence in women who had breast cancer, Letrozole (Femara) has been used in Canada in the past five years and in the U.S. in the past two years instead of clomiphene. It is taken orally in a tablet form at doses of 2.5 to 7.5 mg daily for five days each month. The experience with Arimidex is very limited at present. Ovulation and conception rates are similar to clomiphene. 

Indications:
Similar to clomiphene. 

Contraindications and adverse effects:
Side effects such as hot flashes, mood changes, and headaches are often less pronounced than with clomiphene. Adverse effects on the cervical mucus and uterine lining similarly are less severe than clomiphene. The risk of twins is similar to clomiphene or less.

FEMARA OR ARIMIDEX ARE NOT APPROVED BY THE FDA FOR OVULATION INDUCTION AT PRESENT. PLEASE DISCUSS THEIR USE WITH YOUR REPRODUCTIVE SPECIALIST.