6 Things You May Not Know About Clomid

The Truth About Twins and the Limits of Clomid

Pile of pills as visual of Clomid pills, not actualy photo of clomiphene citrate
Clomid is a very effective medication for women with ovulation problems -- but it's no super drug. Martin Barraud / OJO Images / Getty Images

Even if you haven’t struggled with infertility, you’ve probably heard of Clomid (generically as clomiphene citrate.) Around since the 1960s, Clomid is frequently the first drug given to a woman when she can’t conceive.

Just because the name of the drug is familiar doesn’t mean you really understand what it can do and what it can’t.

Here are six things about Clomid that you may not know.

Your Odds of Conceiving Twins on Clomid are Just 10%

The way people talk you’d think that every other person who tries Clomid gets pregnant with twins.

Nothing could be further from the truth.

According to the research, Clomid leads to a twin pregnancy just 10% of the time.

So, for every 10 couples that conceive while taking Clomid, just one will get pregnant with twins.

This doesn’t mean you should brush off the risk of having a multiple birth. Only that you shouldn’t assume Clomid will get you twins.

Clomid Won’t Help You Get Pregnant Faster if You Don’t Have Ovulation Problems

If you have problems with ovulation, Clomid may help you ovulate. This can help you get pregnant.

But what if you don’t have ovulation problems?

Clomid will not turn you into a baby-making machine.

A study of over 1,000 women looked at whether Clomid could help women who were having trouble getting pregnant but were not having ovulation problems.

When comparing women who took Clomid with women who received either a placebo or no treatment, researchers found that there was no improvement in pregnancy rates, even when Clomid was coupled with IUI treatment.

(IUI is insemination.)

It’s not unheard of for a woman to lie to her doctor to get Clomid, thinking it will help her conceive faster.

Not only will it likely not help her get pregnant faster, but now she’s at risk for experiencing side effects.

Some of Clomid’s Side Effects Can Actually Get in the Way of Getting Pregnant

As I wrote above, Clomid does not turn you into a fertility super woman. It’s great at helping many women ovulate, but making babies takes more than ovulation.

One of the side effects of Clomid is thickening of the cervical mucus.

Cervical mucus is secreted near the cervix to help nourish sperm and help them swim their way into the uterus.

As you near ovulation, your estrogen levels rise. This triggers the production of fertile cervical mucus.

However, Clomid blocks estrogen receptors. This leads to a decrease in fertile cervical mucus quality.

For women that require higher doses of Clomid to trigger ovulation, a doctor may recommend IUI to bypass the cervical mucus problem.

Another unfortunate side effect of Clomid is thinning of the endometrium, the inner uterine lining where an embryo implants itself. A thinner lining can lead to embryo implantation issues, and this may increase your miscarriage risk.

Having a thin endometrial lining is more common in women who use Clomid over multiple cycles or at higher doses.

You Shouldn’t Use Clomid for More Than 6 to 12 Cycles

Compared to other fertility drugs, Clomid is inexpensive and relatively easy to use.

If other fertility treatments are out of your budget, you may be tempted to stick with Clomid for as long as possible.

But Clomid should not be used indefinitely. One reason for that is the possible increased risk of developing ovarian cancer.

Several studies have looked into whether fertility drugs increase your odds for cancer. The good news is that most studies link infertility itself, and not Clomid use, to the increased risk of cancer.

This means if Clomid helps you get pregnant, just getting pregnant and having a baby will decrease your cancer risk.

The bad news is that some studies have found that cancer risk goes up if you’re treated with Clomid over an extended time, even when compared to other infertile women who don’t conceive.

Even though research seems to indicate that infertility itself is the cause for increased cancer odds, just to be safe, most doctors recommend limiting treatment to 12 months. Some prefer to be extra cautious and limit treatment to six months.

Clomid Isn’t Appropriate for Every Infertile Couple

“Why don’t you just try Clomid?” Tell someone you’re struggling to get pregnant, and you may get this advice.

As I’m sure you’ve surmised by now, Clomid isn’t the answer for every couple.

Clomid may not be for you if...

  • You have blocked fallopian tubes, fibroids, or other uterine abnormalities.
  • You have an ovarian cyst. (This is not the same as having the tiny cysts that accompany polycystic ovarian syndrome (PCOS).)
  • You’re dealing with male infertility. (Unless we’re talking about Clomid for men, more on that below.)
  • You have low ovarian reserves, either due to age or primary ovarian insufficiency (formerly known as premature ovarian failure).
  • Your ovulation problems would be better solved by other treatments. (For example, in a woman with hyperprolactinemia, treating the hyperprolactinemia first would be the preferred first step.)
  • You have a hormone-reactive tumor, which may grow with Clomid use, or you have a history of certain cancers.
  • You’ve reacted poorly to Clomid treatment in the past.

Clomid Isn’t Just for Women

Most of this article has concentrated on Clomid use in women, but men may also take Clomid.

Low testosterone can lead to a number of problems in men, including impaired fertility. Most men who take Clomid are trying to conceive, but some may take it to alleviate other symptoms of low testosterone.

You may have read news stories about male athletes taking Clomid. It’s true that Clomid is on the anti-doping list for the NFL and the World Anti-Doping Association.

However, it’s also important to know that Clomid use in men can be legitimate, in the right circumstances.

More on Clomid and fertility treatment:


Hughes E1, Brown J, Collins JJ, Vanderkerchove P. “Clomiphene citrate for unexplained subfertility in women.” Cochrane Database Syst Rev. 2010 Jan 20;(1):CD000057. doi: 10.1002/14651858.CD000057.pub2. http://www.ncbi.nlm.nih.gov/pubmed/20091498

Takasaki A, Tamura H1, Taketani T, Shimamura K, Morioka H, Sugino N. “A pilot study to prevent a thin endometrium in patients undergoing clomiphene citrate treatment.” J Ovarian Res. 2013 Dec 27;6(1):94. doi: 10.1186/1757-2215-6-94. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880974/

Tomao F, Lo Russo G, Spinelli GP, Stati V, Prete AA, Prinzi N, Sinjari M, Vici P, Papa A, Chiotti MS, Benedetti Panici P, Tomao S. “Fertility drugs, reproductive strategies and ovarian cancer risk.” J Ovarian Res. 2014 May 8;7:51. doi: 10.1186/1757-2215-7-51. eCollection 2014. Review. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4020377/

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