Clomid is a popular fertility medication used to induce ovulation. Clomid helps a woman to ovulate by tricking her brain into making more of the hormones FSH and LH. Since LH is the hormone that ovulation tests detect, taking Clomid can cause a false positive result on an ovulation test.
How Clomid works
Clomid tricks a woman’s brain into thinking she is not making enough estrogen. It does this by blocking estrogen receptors. Estrogen is a hormone involved in ovulation. When estrogen levels are low, your body reacts to this by trying to increase your estrogen levels. Estrogen is produced by eggs maturing within the follicles in your ovaries. So, to increase estrogen levels your body responds by kicking up production of the hormones that stimulate your follicles. This will ultimately increase your estrogen levels.
When to use an ovulation test if using Clomid
To avoid getting a false positive result on an ovulation test when taking Clomid, it is best to wait to start using an ovulation test until 3 or 4 days after taking your last tablet of Clomid. This should give your body time to adjust to the medication and give you the most accurate results. Women generally take Clomid for five days and start taking it somewhere between day 3 to 5 of their cycle. Use this chart as a guide for when to start using an ovulation test. If your doctor has recommended a different cycle day to begin taking Clomid, you should ask your doctor for more detailed instructions on when to start testing.
| Clomid Start Day | When to start using an opk |
Cycle Day 3 | 10 |
Cycle Day 4 | 11 |
Cycle Day 5 | 12 |
Other ways to predict ovulation when taking Clomid
Along with using ovulation tests, some doctors recommend using a fertility chart. Fertility charting can be confusing at first, but there are several fertility charting websites and programs out there that make charting a little easier. A BBT chart will help you and your doctor to know if and when you ovulated.
You will want to start your fertility chart on the first day of your cycle if possible. Clomid may affect the patterns on your fertility chart. Women taking Clomid often have higher pre-ovulation temperatures. Even with the higher pre-ovulation temperatures, you should be able to see a temperature shift on your chart if you ovulate while taking Clomid. Keeping a BBT chart can be a good way to confirm that the Clomid dosage you are taking is working because you can verify ovulation on your chart. If you do not see a temperature shift, your doctor may need to adjust your dosage or verify ovulation in another way.