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Clomid is a well-known fertility drug that is commonly used to treat infertility in women who do not ovulate normally. Femara was not developed as a fertility drug, but is frequently used to induce ovulation as well.

There are many similarities between Femara and Clomid, but also some important differences. If you have been diagnosed with anovulation, should you take Femara or Clomid? 


Clomid, generically known as clomiphene citrate and also sold under the brand name Serophene, is the most commonly prescribed fertility drugs today. Clomid works by stimulating the pituitary gland to encourage the ovaries to develop mature eggs. Clomid has been received as a bit of a miracle drug among women who have trouble conceiving naturally, and even those who just think they may be infertile. Clomid is widely advertised online, by those who seek to sell it to women hoping to get pregnant but who don't have a prescription because their doctor told them to lose weight first, for instance. Despite its reputation, it is important not to lose sight of the fact that Clomid only works for women who do not ovulate naturally. Around 80 percent of women who do have ovulation disorders will ovulate once they start taking Clomid.

Despite this huge "success rate", not all women who start ovulating once they use Clomid will also get pregnant thanks to the drug. Clomid has a considerable amount of short-term side effects. Ovarian hyperstimulation syndrome is one such side effect, that is potentially very dangerous. Nausea, mood swings, depression and breast tenderness are more common side effects of Clomid. Twin pregnancy is a more famous side effect of Clomid this even earned it the nickname "twin drug", and some women will take clomiphene specifically to conceive more than one baby. The chance of having twins goes up by 10 percent if you take Clomid. That's a lot, but you still have a tiny chance of having twins.

Clomid and Femara are pretty similar in some ways, as you will see in the next section. There are two negative side effects that Clomid has, which don't go along with Femara, however. Clomid can reduce a woman's cervical mucus for six to eight weeks, something that actually negatively impacts her chances of conceiving. It can also make the lining of the uterus the endometrium thinner. Thinner uterine lining reduces the chances that a fertilized egg will implant into the uterus. Although there is no evidence that there are long-term side effects, taking the drug for longer than six cycles is not recommended. Research into any possible long-term side effects of clomiphene citratem, both to the mother and babies, is ongoing.


Femara, also known as Letrozole, is FDA approved as a breast cancer drug. The manufacturer never filed for it to be approved as a fertility medication. Yet, it has been used as an ovarian stimulation drug off label since 2001. Femara is generally associated with fewer side effects than Clomid. It clears from the body more quickly than Clomid does, which means that the short-term side effects a woman may experience while taking this drug the same ones that apply to Clomid, namely nausea, hot flashes, mood swings and the like, see

Femara drug side effects for more info don't last beyond the cycle in which it is used. The other distinct advantage is that Femara leaves the endometrium and cervical mucus intact. The other advantage is that women have a lower risk of conceiving twins and higher order multiples on Femara, compared to Clomid. Considering the potential for complications that accompany twin pregnancies, this is a rather crucial thing to take into account. Is Femara really safe as a fertility drug? Despite its relatively wide use, that is not quite clear. A Canadian study that was presented at a conference in 2005 suggests that Femara is associated with a higher risk of birth defects than Clomid, while a follow-up study suggested the opposite that Clomid carries double the risk of congenital birth defects and chromosomal abnormalities than Femara, at 2.4 percent vs 4.8 percent.

The manufacturer of Femara not only didn't ask the FDA to approve it as an ovarian stimulation drug, they actually went a step further by asking physicians not to prescribe it as such. Some speculate that this is only because of liability issues, but it is certainly something women who may take Femara to induce ovulation may want to know about.
It is also interesting that India banned Femara's use as a fertility drug in 2011, because of concerns about birth defects.

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