Clomifene

Key facts

• Clomifene (clomiphene) is an oral fertility medicine that induces ovulation in women who ovulate irregularly or not at all.
• It is taken for a short course, usually five days early in the menstrual cycle, and treatment is normally limited to a small number of cycles because of the risks below and diminishing benefit with longer use.
• It raises the chance of ovarian hyperstimulation, where the ovaries swell and become painful, and increases the chance of a multiple pregnancy such as twins.
• Seek urgent care for severe abdominal or pelvic pain, rapid weight gain, bloating, or sudden vision changes.

What clomifene treats

Clomifene treats anovulatory infertility, difficulty conceiving because the ovaries are not releasing an egg regularly, most often due to polycystic ovary syndrome. It is used to stimulate ovulation as part of fertility treatment, sometimes alongside monitoring by ultrasound to time intercourse or other fertility procedures.

How clomifene works

Clomifene blocks oestrogen receptors in the brain's hypothalamus and pituitary gland. The brain reads this as a signal that oestrogen levels are low, so it releases more follicle-stimulating hormone and luteinising hormone. These hormones drive the ovary to develop and release an egg, restoring ovulation in women who were not ovulating regularly.

Before you take it

• Do not take clomifene if you are already pregnant, have unexplained abnormal vaginal bleeding, or have ovarian cysts unrelated to polycystic ovary syndrome, or significant liver disease.
• Tell your prescriber about any history of vision problems, since clomifene can cause visual disturbances that may affect activities such as driving.
• Treatment is usually limited to a small number of cycles; your prescriber will review response with ultrasound or hormone testing and reconsider the plan if ovulation or pregnancy does not occur.
• Discuss the increased chance of a multiple pregnancy with your prescriber before starting, as this carries added risks for you and the pregnancy.

Side effects

Common effects include hot flushes, bloating, breast tenderness, mood changes and mild pelvic discomfort.

Stop and seek urgent medical care for any of these:

• Severe or worsening abdominal or pelvic pain, bloating or rapid weight gain, which can signal ovarian hyperstimulation.
• Sudden vision changes, blurred vision or seeing flashing lights.
• Severe headache.
• Shortness of breath or leg swelling.

Safety essentials

• Ovarian hyperstimulation and multiple pregnancy are the defining risks of clomifene; report severe pelvic pain, bloating or rapid weight gain immediately, and discuss the multiple-pregnancy chance before you start treatment.
• Clomifene is prescribed for a limited number of cycles only; taking it for longer than advised does not improve the chance of pregnancy and increases risk.
• Tell your prescriber straight away if you develop visual disturbances, and stop treatment and seek review if this happens.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.