Clomid® (Clomiphene citrate) or Letrozole are used in women who do not ovulate (produce eggs) regularly each month leading to infertility. These medicines stimulate eggs to develop in the ovaries and be released for fertilisation. These medications will work best for you if you maintain your BMI between 19 and 30.

How and when should I take this medication?

  • Clomid® or Letrozole are tablets taken by mouth.
  • Take one tablet a day from day 2 to 6 of your normal cycle – 5 days in total. Day 1 is the first day you wake up with fresh bleeding.
  • The initial dose of Clomid® is 50mg.
  • The initial dose of Letrozole is 2.5mg.

The outcome

  • If your period comes by day 35, start taking your prescribed medication again from day 2 of your cycle.
  • If this does not happen, take a pregnancy test to check that you are not pregnant, either through your GP or a home testing kit.
  • If you are not pregnant, the medication should be tried again as instructed.
  • If you do not have periods, a course of progestogens either Norethisterone or Provera® will be given to stimulate menstruation. You will then begin your ovulation induction medication on the second day of your induced period.

How do I know that the ovulation induction medication is working?

  • Your cycle should settle into a regular pattern. Blood tests will be done to check the level of progesterone around day 21 to 23.
  • Your fertility specialist will review your response to the medication. The results will be sent to you, by your specialist, with advice about increasing or decreasing the dose as needed.

Side effects and risks

The safety of Letrozole and Clomid® has been studied for many years. There is a 5 to 10% risk of having twins and occasionally, triplets or higher multiple births.

The rate of miscarriage or congenital anomalies are not increased when taking either of the medications.

Side effects of Clomid®

Side effects are not common and tend to be dose related. Frequent side effects include headaches, nausea, hot flushes, breast tenderness and fluid retention but most people tolerate the medication well.

You should stop taking Clomid® if you get blurred vision or double vision.

Following research, it is recommended that Clomid® should only be used for a maximum of 6 to 12 cycles.

Side effects of Letrozole

Similarly, side effects are not common and tend to be dose related. Frequent side effects include gastrointestinal disturbances, nausea, hot flushes, breast tenderness, blurred vision, mood changes and headaches.

Response to treatment

Around 70 in every 100 patients treated with an ovulation induction agent will ovulate and 40 in every 100 will conceive.

If your consultant feels that you are not responding to Letrozole or Clomid® you will be offered Gonadotrophin.

For more information, please ask for a copy of leaflet ‘Gonadotrophin ovulation induction GHPI1085’.

Contact information

If you have any questions, please contact the fertility nurses via Mrs K Reddy’s secretary on the number below.

Cotswold Fertility Unit

Tel: 0300 422 3128

Monday to Friday 8:00am to 4:00pm


Printable version of this page

Ovulation induction with oral agents Clomid® and Letrozole GHPI0463_07_23 Department: Gynaecology Review due: July 2026 PDF, 318.8 KB, 3 pages
Reference number GHPI0463_07_23
Department Gynaecology
Review due July 2026