Emergency contraceptives use levongestrel as the progesterone, so why do yaz, (drospirenone and ethinyl estradiol) yasmin, beyaz contain drospirenone instead?

Side-effects: There are many different types of progesterone. The positive and negative effects of a birth-control pill are determined by the type of progesterone in the pill. Drospirenone is good for preventing water retention and excessive hair growth but it increases the risk of blood clot formation in legs and lungs. Its not effective for emergency contraception. Levonorgestrel works best for this.

Agree w Dr. Whiting.: Drospirenone / ethinyl estradiol oral contraceptives are not effective for emergency contraception. Check reference chart to see which oral contraceptives can be used for emergency contraception and at what doses. http://ec.princeton.edu/questions/dose.html#dose