There are three types of ovulation-promoting drugs commonly used in clinical practice, the oral ones are clomiphene and letrozole, and the intramuscular one is chorionic gonadotropin. There is no such thing as the best ovulation stimulating drug, only the difference in follicle growth and development after use. Some women are able to have good ovulation after taking clomiphene orally, and with open fallopian tubes, it is possible to promote eggs once and get pregnant. However, some women have poor follicular growth or no mature follicles at all after taking clomiphene, so they may need to be injected with chlamydia to promote follicular rupture before they can get pregnant. Other women need to take oral letrozole before their follicles can grow well, so the choice of ovulation-promoting drugs can only be made on a case-by-case basis. In some women, oral ovulation medication does not help much, so the only way to promote ovulation is through intramuscular injection.