Clomid (Clomiphene) Side Effects and Risks

Mood Swings, Headaches, Bloating, and Twins

Clomid side effects are mild for most people. 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 are all the same drug. 

Many Clomid side effects are the result of how the drug works. If you're wondering how Clomid affects the chance to conceive of twins, this quiz may help

Clomid 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.

Important note! 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. The information in this article does not replace consultation with a medical professional.

Hot Flashes

Woman sweating, having a hot flash from Clomid side effects
Hot flashes are the most common Clomid side effect. Tetra Images / Getty Images

Hot flashes (or, in official 'doctor speak,' vasomotor flushes) are a common side effect of clomiphene. About 10% of women experienced them in clinical studies.

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

  • suddenly feel extremely warm
  • 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

woman with bloating from Clomid side effects
You may experience bloating and abdominal tenderness while taking Clomid. Peter Dazeley / Getty Images

Another very common clomiphene side effect is bloating and abdominal discomfort. Research has found it occurred in about 5% 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. (More on this below.)

Weight Gain

Woman standing on scale wondering if she gained weight from Clomid
Any weight you gain from Clomid should be temporary. Quiet Noise Creative / Getty Images

Weight gain isn’t as common as bloating, with less than 1% of women reporting weight changes. But it’s a side effect that you hear often through the infertility grapevine.

If the weight gain is connected to bloating, then your weight should go back to normal after treatment.

Mood Swings

Woman feeling anxious from Clomid induced mood swings
The Clomid crazies aren't all in your head. Jamie Grill / Getty Images

Mood swings are another side effect of clomiphene that in clinical studies didn’t appear as often as you might imagine (less than 1% of women).

However, later studies found that almost half of all women experience mood disturbances on Clomid.

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

Woman feeling dizzy
If you feel dizzy while taking clomiphene, be very careful when driving. Dreaming Poet / Shutterstock

About 2% of women 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

woman with hand across chest, breast tenderness from Clomid
Your breasts may be more sensitive to touch when you're taking Clomid. JGI/Jamie Grill / Getty Images

Breast tenderness is another potential side effect of clomiphene, occurring in 2% of women during clinical trials.

This is another side effect that can have women wondering if they’re experiencing early pregnancy symptoms, but usually it’s just a drug side effect.

Abnormal Menstrual Bleeding

Ink in water as metaphor for spotting
You may have light spotting when taking Clomid. Henrik Sorensen / Getty Images

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

This can drive some women crazy. They see spotting and think, “Oh, it’s 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.

If the spotting is accompanied by other symptoms like...

  • abdominal pain
  • nausea and vomiting
  • fever
  • or, something just doesn’t feel right contact your doctor.


Woman with a headache from Clomid
Taking Clomid in the evening helps reduce headaches for some women. BSIP/UIG / Getty Images

A little over 1% of women in clinical trials reported headaches.

If you’re experiencing headaches, it may help to take the medication in the evening. This way, you can sleep through them.

(If your doctor told you to specifically take the medication in the morning, ask first.)

You should also be sure to get plenty of fluids since mild dehydration can cause headaches.

Vaginal Dryness or Thick Cervical Mucus

woman putting lotion in her hand
Make sure you use a sperm-friendly lubricant if Clomid causes vaginal dryness for you. RunPhoto / Getty Images

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. He 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 blurred highway road.
If you experience blurred vision while taking clomiphene, be very cautious driving. Rickyd / Shutterstock

A frightening, but usually not dangerous, side effect of clomiphene is blurred vision. It occurred in 1.5% of women during clinical trials.

Vision disturbances may include...

  • blurred vision
  • seeing flashing lights
  • seeing floaters 

This is more likely at higher doses. 

If you experience vision changes, be sure to contact your doctor right away. The symptoms should go away once the medication is stopped. (And, obviously, you should take care in driving or operating dangerous equipment if you experience visual side effects.)

Risks of Clomid

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. With that said, 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 risks of clomiphene. During clinical trials, 6.9% of pregnancies were twin pregnancies, 0.5% were triplets, 0.3% were quadruplets, and 0.1% were quintuplets. To reduce the chances of having twins, your doctor should always start you on the lowest dose first, 50 mg, before trying higher doses.

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: Less than 1% of women will develop an ovarian cyst during treatment. The cyst is typically benign (not cancer), 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.

More on fertility drugs and treatment:


Clomid Drug Information Sheet. Sanofi-Aventis. Accessed February 24, 2009.

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