Clomiphene (Clomid) Side Effects and Risks

Clomid (clomiphene) side effects are mild for most people. The most common ones include hot flashes, headaches, bloating or other abdominal discomfort, mood swings, blurred vision, and breast tenderness. Temporary weight gain may occur due to bloating. Fatigue is a less common side effect of taking Clomid.

However, as with any drug, you should be aware of the potential risks before treatment. Clomid may also be sold under its generic name clomiphene or under the brand name Serophene. These medications are all the same drug.

Many Clomid side effects are the result of how the drug works. Clomiphene tricks the body into thinking there’s not enough estrogen. It does this by blocking estrogen receptors.

This leads the body to release more GnRH, a hormone that tells the pituitary to release more FSH and LH. These hormones stimulate the ovaries and boost ovulation.

Because most of the estrogen receptors are blocked, this leads to some of clomiphene’s side effects like headaches and vaginal dryness. Most of the other side effects are caused by the ovaries becoming slightly enlarged.

Clomid side effects — Illustration by JR Bee, Verywell

Not all possible side effects and risks are listed below. If you are experiencing severe side effects, unusual symptoms, or are concerned for any reason, contact your doctor.

Consult with your doctor to get a personalized assessment of your risks for various side effects and to address any questions or concerns you may have.

Hot Flashes

Hot flashes (or, in official doctor-speak, "vasomotor flushes") are a common side effect of clomiphene. About 1 in 10 people experienced them in clinical studies.

When you’re having a hot flash, you may:

Suddenly feel extremely warm from within
Experience face flush
Break out in a sweat
Have a more rapid heartbeat

After a hot flash, you might feel chilled, especially if you broke out in a sweat. Hot flashes are also known as night sweats if they happen while you’re sleeping.

A hot flash can be a bit unnerving the first time it happens. That said, it’s not a dangerous event—just an uncomfortable one.

Bloating and Abdominal Discomfort

Another very common clomiphene side effect is bloating and abdominal discomfort. Research has found it occurred in about 6% of women.

Wearing clothing that isn’t too tight around the waist may help. The bloated feelings should pass once your treatment cycle is over.

Of course, if you experience more than moderate discomfort and cramps, call your doctor. Severe bloating or abdominal tenderness may be a sign of ovarian hyperstimulation syndrome.

Weight Gain

Weight gain isn’t as common a common side effect, with less than 1 in 100 people reporting weight changes in early clinical studies. But it’s a side effect that you hear often through the infertility grapevine.

What might explain why so few reported weight gain in early research, but so many people online complain about adding on pounds when taking Clomid?

One possible explanation is the weight gain is a temporary outcome of bloating. Bloating is common during Clomid treatment, as is retaining water weight. If the weight gain is connected to bloating, then your weight should go back to normal after treatment.

Another possibility is the stress of treatment leads to unhealthy eating. The best way to combat this is to plan your meals and have healthy, fertility-friendly snacks around when you get the munchies.

Mood Swings

Mood swings are another side effect of clomiphene that in early, pre-approval, clinical studies was not frequently reported (less than 1% of people).

However, later studies found that almost half of all people taking Clomid experience mood disturbances.

Mood swings may mean feeling more emotionally sensitive, tearful, or even depressed or anxious. Infertility itself can bring on these feelings without drugs. Try to be forgiving and gentle with yourself and practice good self-care during treatment.

Nausea and Dizziness

About 2% of people experience nausea and vomiting while taking clomiphene. Taking the medication in the evening may help. If the nausea is intense, or you have trouble keeping down food and fluids, be sure to report this to your doctor.

Severe nausea can also be a sign of ovarian hyperstimulation syndrome, a rare but potentially dangerous side effect of fertility drugs.

Breast Tenderness

Breast tenderness is another potential side effect of clomiphene, occurring in 2% of people during clinical trials. This is another side effect that might lead you to wonder if you're experiencing early pregnancy symptoms. But usually, it’s just a drug side effect.

Abnormal Menstrual Bleeding

Just over 1% of people in Clomid clinical trials reported spotting or abnormal menstrual bleeding.

Some people may see spotting and think that it is implantation spotting. But if you’re taking fertility drugs, spotting in the middle of your cycle can be related to the drugs. You shouldn't necessarily assume it's a pregnancy sign.

Contact your doctor if the spotting is accompanied by other symptoms, such as:

Abdominal pain
Fever
Nausea and vomiting
A feeling that something isn't right

Headaches

A little over 1% of people in clinical trials reported headaches when taking Clomid.

If you’re experiencing headaches, it may help to take the medication in the evening. This way, you can sleep through the pain. (If your doctor told you to specifically take the medication in the morning, ask first.) Also be sure to get plenty of fluids, since mild dehydration can cause headaches.

Vaginal Dryness or Thick Cervical Mucus

This is a frustrating potential side effect of clomiphene, as thick or absent cervical fluid can interfere with achieving pregnancy.

Cervical mucus is needed to help transport the sperm into the cervix. If clomiphene causes thick cervical mucus, this can decrease the chances of getting pregnant.

Let your doctor know if this happens during treatment. They can consider whether clomiphene is the right drug for you, or find a way to treat or bypass the problem (like with IUI treatment).

You may want to try using a sperm-friendly lubricant to make sex more comfortable.

Blurred Vision

A frightening, but usually not dangerous, side effect of clomiphene is blurred vision and other visual side effects. Blurred vision occurred in 1.5% of people during clinical trials. This is more likely at higher doses.

Vision disturbances may include:

Blurred vision
Seeing flashing lights
Seeing floaters

Obviously, you should take care in driving or operating dangerous equipment if you experience visual side effects.

If you experience vision changes, be sure to contact your doctor right away. The symptoms should go away once the medication is stopped.

Additional Risks

While side effects are usually physical or emotional discomforts experienced while taking a drug, a drug's risks are what may occur beyond what you feel.

Here are the possible risks to Clomid:

Twin or multiple pregnancy: The risk of getting pregnant with twins or more may be the most well-known side effect of clomiphene. Data from the National Birth Defects Prevention Study, 1997–2005, shows 11.7% of pregnancies were twin pregnancies and 1.1% were triplets or quadruplets.

To reduce the chances of having twins, your doctor should always start you on the lowest dose first. Additionally, your doctor can do a mid-cycle scan to estimate the number of follicles and determine whether or not there is a high probability of twins or multiples. Together, you can determine at that time if you want to skip that cycle of proceed accordingly.

Ovarian hyperstimulation syndrome (OHSS): Usually mild with clomiphene treatment, but in rare cases, the severe form can occur. Without treatment, severe OHSS can be life-threatening.

If you experience nausea, severe abdominal or pelvic pain, sudden weight gain, or severe bloating, contact your doctor immediately.

Irreversible vision disturbances: Extremely rare, only in those who continue treatment after vision disturbance began. In those who discontinued treatment, vision disturbance stopped after three days.

Ovarian cysts: 15.4% of people will develop an ovarian cyst during treatment. The cyst is typically benign (not cancerous), and it should go away on its own not long after the treatment cycle is over. If the cyst does not go away, the doctor should follow up and reevaluate. In rare cases, it may require surgical intervention.

Ovarian cancer: Some studies have found an increased risk of ovarian cancer if clomiphene is taken for a year or longer. It's unclear if this is caused by clomiphene or infertility itself.

Strategies to Reduce Side Effects

You can't completely avoid potential side effects of Clomid or eliminate all risks, but there are things you or your doctor can do to help possibly reduce them.

Start on the lowest dose possible: More doesn't necessarily mean better. Your doctor is likely to start you at the lowest dose, but if the first cycle fails, they may encourage you to try again at the same dose. You might think a higher dose would be better, but this isn't necessarily true.
Take the pill in the evening: If you're getting headaches, taking Clomid before bed may help.
Monitor your diet: Weight gain can occur while taking Clomid, but most of that weight gain should be temporary. Weight gain that comes from bloating and water retention will go away. However, the weight you gain from stress eating while taking Clomid will stay.
Practice good self-care: Mood swings on Clomid are real. They aren't "just in your head." The best way to cope with this side effect is to take good care of yourself. Get enough sleep, eat well, and seek the support of friends and family.
Dress in layers: If you're experiencing hot flashes, dress in layers. This way, if you suddenly feel overheated, you can take something off and cool down a little quicker. Drinking something cold can also help you cool down.

9 Sources

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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By Rachel Gurevich, RN
Rachel Gurevich is a fertility advocate, author, and recipient of The Hope Award for Achievement, from Resolve: The National Infertility Association. She is a professional member of the Association of Health Care Journalists and has been writing about women’s health since 2001. Rachel uses her own experiences with infertility to write compassionate, practical, and supportive articles.

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Clomid Side Effects and Risks