The fertility medication Clomid is commonly used for ovarian stimulation
Clomiphene citrate (which goes by the brand names Clomid™ or Serophene™) is used to achieve ovulation in women who either do not ovulate at all or do not ovulate regularly. These women have a condition called “ovulatory dysfunction”, which is one of the most common causes of infertility. Clomid is also used in the treatment of unexplained infertility, which is discussed elsewhere on our web site.
Clomiphene is a complicated molecule, as it causes both estrogenic and anti-estrogenic actions. It is in the category of medications called SERMs (selective estrogen receptor modulators). These medications bind to receptors in the hypothalamus and pituitary to increase the production of GnRH and subsequently FSH, which are the main hormones responsible for follicular development. Approximately 75% of women with ovulatory dysfunction will ovulate in response to Clomid. A conception rate of 8-12% per cycle has been reported, with a cumulative chance for conception approaching 60% following six cycles of treatment.
Clomid is supplied in 50 mg pills.
Typically, patients begin treatment with one pill per day for five days, starting early in the cycle. There is no clinical benefit to increasing the dose of medication once the dose that causes normal ovulation has been determined. Clomid treatment should be limited to six ovulatory cycles as 95% of patients who conceive on Clomid do so within the first six ovulatory cycles. Complications of Clomid can include hot flashes, ovarian enlargement with bloating and abdominal distention, nausea, vomiting, headache, and abnormal uterine bleeding.
Women treated with Clomid should have a baseline ultrasound performed early in their menstrual cycle to exclude the presence of a cyst. If no cyst is present, Clomid treatment is given for five days. A repeat ultrasound is typically performed approximately five to seven days after the last Clomid tablet in order to evaluate the patient’s response. To accomplish this, the number and size of the developing follicles and the endometrial thickness are measured. If a large “preovulatory” follicle is present, the patient will be given instructions on when to use an ovulation kit or a ‘trigger shot’.
Other medications that physicians may use for ovulation induction include the category of medications known as aromatase inhibitors, such as tamoxifen and letrozole. Letrozole’s trade name is Femara™; it is a medication approved by the FDA for the treatment of breast cancer. It has not been FDA approved for fertility treatment. Current evidence suggests that letrozole is not associated with an increased risk of birth defects. Some patients who use Clomid will experience thinning of the uterine lining; Femara may be a good alternative in this particular group of patients. The main side effects of letrozole are fatigue, headaches, and dizziness.
A subset of women with ovulatory dysfunction have a condition called polycystic ovarian syndrome (PCOS), which is characterized by irregular ovulation, elevated androgen (male hormone) levels, and (commonly) insulin resistance. Patients with PCOS will usually ovulate when given either Clomid or Femara. A recent large randomized study found that Femara was associated with higher live-birth and ovulation rates among infertile women with PCOS when compared to Clomid.