The Facts About Clomid

Among the Most Prescribed Fertility Drugs in the World

Pros and Cons of Taking Clomid for Infertility

Verywell / Nusha Ashjaee 

Clomid is an ovulatory stimulating drug used to help women who have problems with ovulation. It is the most commonly used fertility drug. Because Clomid can be prescribed by a gynecologist and doesn't require a fertility specialist, it's also the very first fertility treatment tried for most couples.

Clomid is taken as a pill. This is unlike the stronger fertility drugs, which require injection. Clomid may also be marketed under the name Serophene, or you may see it sold under its generic name, clomiphene citrate.

Clomid is very effective, stimulating ovulation 80% of the time.

Note: Clomid can also be used as a treatment for male infertility. This article focuses on Clomid treatment in women.


If a woman has irregular cycles, or anovulatory cycles (menstruation without ovulation), Clomid may be tried first. Clomid is often used in treating polycystic ovarian syndrome (PCOS) related infertility

It may also be used in cases of unexplained infertility or when a couple prefers not to use the more expensive and invasive fertility treatments. (However, it's important to remember that the more expensive treatment is sometimes the most appropriate.)

Clomid may also be used during IUI (intrauterine insemination) or IVF procedures. With IVF, Clomid may be used in conjunction with injectable ovulation medications to elicit a stronger response.


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 PCOS.)
  • You have a thin endometrial lining.
  • You’re dealing with male infertility (unless your male partner has a condition that is being treated with Clomid).
  • 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 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.

Use Without Ovulation Issues

If you have problems with ovulation, Clomid may help you ovulate. But what if you don’t have ovulation problems?

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.

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 which reduce fertility.

Drug Protocol

You should follow the directions your doctor gives you. Doctors may have slightly different protocols for taking the medication. With that said, the most common dosage of Clomid is 50 mg taken for five days, on Days 3 through 7 of your cycle. Some doctors prefer you to take the pills on Days 5 through 9 of your cycle.

Does it matter if your doctor suggests the Day 3 to 7 protocol or the Day 5 to 9 one? Not really.

Ovulation and pregnancy rates have been shown to be similar whether the drug is started on day two, three, four, or five. Don't feel concerned if your doctor tells you a different protocol to follow than your friend.

If 50 mg doesn't work, your doctor may increase the medication. Or, they may give it another try at 50 mg. You might think that more is always better, but higher doses, especially at or above 150 mg, can make conception more difficult. (See below, under side effects.)

When to Have Sex

To get pregnant when taking Clomid, you need to have sexual intercourse when you are most fertile. This will be the few days just before ovulation.

This varies slightly from person to person, but most women ovulate 7 to 10 days after the last Clomid pill was taken. This means you are most likely to ovulate somewhere between Day 14 and 19 of your cycle.

To have sex during your most fertile time (which is the two to three days before you ovulate), you may want to consider having sex every other day start on Day 11 and ending on Day 21.

Another option is to use an ovulation predictor test to detect your most fertile time. Whenever the test indicates you're fertile, have sex that day and the next few days.

If you're also having a trigger shot (injection of hCG) during your Clomid cycle, your doctor will instruct you to have sexual intercourse on the day of the injection and the two following days. For example, if you have the injection on Monday, you should have sex on Monday, Tuesday, and Wednesday.

Common Side Effects

Clomid's side effects aren't so bad, as far as fertility drugs are concerned. The most common side effects are hot flashes, breast tenderness, mood swings, and nausea. Once the medication is stopped, the side effects will leave, too. Possible side effects of Clomid include:

  • Enlarged and tender ovaries (noted in 14% of patients)
  • Hot flashes (11%)
  • Abdominal tenderness, due to enlarged and tender ovaries (7.4%)
  • Bloating (5.5%)
  • Breast tenderness (2.1%)
  • Vaginal dryness or thicker cervical mucus (percentage of occurrence not available)
  • Nausea and vomiting (2.2%)
  • Anxiety and insomnia (1.9%)
  • Vision disturbances (1.6%)
  • Headache (1.3%)
  • Abnormal uterine bleeding/spotting (0.5%)
  • Mood swings and fatigue (0.3%)

One of the more ironic side effects to comprehend is that Clomid can decrease the quality of your cervical mucus. This can cause problems with sperm being able to move easily through the cervix, making conception more difficult.

Clomid can also make the lining of your uterus thinner and less ideal for implantation. This is why more is not necessarily better when it comes to Clomid dosage and use.

Likelihood of Twins

The side effect you're probably most familiar with is the risk of multiples. It's not nearly as common as you may think it is. You have a 10% chance of having twins when taking Clomid. This means that 1 in 10 pregnancies conceived with Clomid lead to 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. Triplets or quadruplets on Clomid are rare, happening less than 1% of the time.

Mood Swings

Clomid does mess with your hormones, and your hormones do have an effect on your emotional well-being. Research on mood swings while taking Clomid indicates a much higher rate than the initial clinical trials of the drug. The clinical trials reported that only 0.3% of women experienced mood swings or fatigue. That breaks down to 3 in 1,000 patients.

However, later research found that between 40% and 45% of women experienced mood swings. That's almost one in every two women. The "Clomid Crazies" are a bit like PMS mood swings—but slightly worse. However, if you experience severe mood swings on Clomid, be sure to contact your doctor.

Success Rate

Clomid will jump-start ovulation in 80% of patients, but ovulating doesn't guarantee pregnancy will occur. While Clomid does help many women ovulate, obviously it's not always successful. When Clomid does not result in ovulation, we say the woman is Clomid resistant. (This isn't the same as when Clomid does trigger ovulation but doesn't lead to pregnancy.)

About 40% to 45% of women using Clomid will get pregnant within six cycles of use.

What happens when Clomid doesn’t work? You won’t necessarily need to move up to more complicated treatments right away. Your doctor may prescribe the diabetes drug metformin to take alongside Clomid.

Or, they may move you onto a drug called letrozole. Letrozole—which is a cancer treatment drug used off-label for infertility—has been found to help women who are Clomid-resistant ovulate .


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 of cancer. The good news is that most studies link infertility itself, and not Clomid use, to the higher 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.


There are reputable pharmacy websites where you can fill a prescription for Clomid, but you should never try taking Clomid without a doctor's supervision. First of all, the only way to purchase Clomid without a prescription is via illegal and shady websites. You have no idea who is selling you the drugs and no way to know if you're getting Clomid or something else.

Secondly, even though Clomid treatment is relatively simple, it is not for everyone, and it can be harmful. You should never buy Clomid online without a prescription.

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6 Sources
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