If you’re just getting started with fertility treatment, all the different medications can be confusing. Lots of people have heard about Clomid (clomiphene citrate), because it’s one of the oldest fertility drugs. But what about Femara? Is that the same as letrozole?
Femara and letrozole are the same thing — Femara is a brand name and letrozole is the generic. Typically, doctors will start fertility patients on either Femara/ letrozole or Clomid as a first line of treatment.
Letrozole was originally developed as a breast cancer drug for post-menopausal women. It is part of a class of medications called aromatase inhibitors. That means it blocks aromatase, an enzyme involved in the production of estrogen.
Estrogen causes some breast cancers to grow, which is why a drug that lowers estrogen can help treat cancer. Researchers also found that lowering estrogen causes the pituitary glands to produce the hormones needed for ovulation.
If you don’t ovulate on a regular schedule due to PCOS or another condition, Femara/ letrozole may help. It stimulates the ovaries to produce follicles, which are the structures that house the all-important eggs.
How to get a prescription for Femara (letrozole)
Like all fertility medications, Femara (letrozole) requires a prescription — you can’t get it over-the-counter. You will probably need to see an ob/gyn or an RE for that. For more info on the different specialists you may see on your fertility journey, check out the posts Can Your PCP Prescribe Clomid (and Other Fertility Meds)? and Graduating from an RE to an OB for Prenatal Care.
Some fertility doctors require certain tests before trying drugs like Femara and Clomid to induce ovulation. For example, you may need to have an HSG to confirm that your uterus and fallopian tubes are normal. For info on HSGs and what to expect, check out this post.
Fertility patients prescribed letrozole may run into issues at the pharmacy because the drug is more often used to treat cancer. Sometimes insurance companies don’t want to cover drugs used for off-label purposes, and pharmacists may ask why the script is for only 5 pills. (I didn’t have any problems, but apparently some people do.)
What to expect when you start taking Femara (letrozole)
Usually, you would take 2.5mg or 5 mg of letrozole each day for five days in the beginning half of your cycle. For example, you might take it Days 3-7 or Days 5-9, with Day 1 being the first day of your period. Remember that in a textbook cycle, you’d ovulate on CD 14.
You would likely have an ultrasound around CD 10 to check on your developing follicles.
- GOOD RESPONSE: One or two follicles around 10mm on CD 10.
- POOR RESPONSE: No measurable follicles on CD 10. Your doctor may increase the dose of letrozole (up to 7.5 mg per day) or have you switch to Clomid next time to see if that works better for you.
- OVER-RESPONSE: Too many follicles (3-4+) that are mature or close to mature at ovulation. Over-response increases the chances of ovarian hyperstimulation syndrome (OHSS) and multiples pregnancy. Both of these scenarios are more common with injectable fertility meds.
Before you panic, though, remember that not all of the follicles seen on a CD 10 ultrasound will keep growing. Most of them will stop growing or even shrink before you ovulate! In a textbook cycle, one follicle will take the lead.
So even if it looks like you have a lot of follicles, CD 10 is probably too soon to tell if you’ve over-responded to letrozole. Your doctor will likely do more scans over the next few days to see how many of those follicles continue to grow to a mature size.
Note that a trigger shot will cause all the follicles close to mature size to release their eggs, not just the biggest one! If you’re ready to ovulate and you have 5 follicles at 15mm, 17mm, 17mm, 18mm, and 20mm respectively (and you’re not doing IVF), your doctor will probably advise you to cancel rather than risk conceiving higher-order multiples.
For more info on cancelled cycles, check out this post. For more info on trigger shots and their potential impact on home pregnancy tests, read this post. Will Clomid Make You Have Twins? has more details on the connection between fertility meds and twins (or more!).
Femara (letrozole) warnings
If you Google Femara (letrozole) or read the materials that came with your prescription, you may see warnings about birth defects. Why would your doctor prescribe something for infertility that isn’t safe for pregnancy?!
The risk for birth defects only comes into play when Femara is taken during pregnancy. That’s long after a fertility patient would be taking it. Used off-label as a fertility drug, Femara is taken before ovulation even occurs.
In addition, Femara metabolizes faster than Clomid does. It would be out of your system before implantation would occur. So those warnings really don’t apply to Femara’s use as a fertility drug.
Differences between Femara (letrozole) and Clomid
Femara (letrozole) was approved as a breast cancer drug in the 1990s, and it’s been used for ovulation induction since 2001. Clomid, in contrast, was approved by the FDA in 1967. It is probably the most well-known and well-studied fertility drug out there.
Clomid makes the body think estrogen is lower than it actually is. That’s different from Femara, which does actually lower estrogen.
So which one works better? It’s really hard to say. You may have to try both and see how you respond.
But it’s not surprising that people sought an alternative to Clomid, because Clomid does have some well-known side effects for a lot of women:
- Clomid has been shown to cause lower quality cervical mucus and a thinner uterine lining, especially after multiple rounds. If you have trouble building and maintaining an adequate lining (at least 8mm), letrozole may be a better option than Clomid. For more info on the importance of a good uterine lining for implantation, see this post.
- Clomid is also famous for causing irritability, mood swings, and hot flashes. Those side effects are less common with letrozole.
My doctor didn’t have me try Clomid at all, partly because I struggled with thin uterine linings. Also, letrozole is believed to be more effective for women like me, with long cycles and PCOS. I did 5 rounds of letrozole before moving on to injectables.
I should say that I did develop good follicles and ovulated during each of those 5 rounds of letrozole. Otherwise, there wouldn’t have been much point in continuing with it!
Differences between Femara (letrozole) and injectable fertility drugs (Gonal-F, Menopur, etc.)
Most doctors try non-IVF fertility patients on letrozole and/ or Clomid before trying injectables. Compared to oral fertility medications, injectables are:
- Stronger
- More likely to lead to a multiples pregnancy
- More complicated to use
- More expensive, both in terms of the medication itself and the increased monitoring required (more ultrasounds)
Letrozole and Clomid tend to be available at regular neighborhood pharmacies, but injections usually have to be ordered through a specialty mail-order pharmacy.
Injectables may also need to be refrigerated, or at least kept within a certain temperature range. That is important to keep in mind when traveling with them. For more info, see Why Are So Many Fertility Medications Refrigerated?
Combo cycles
Some doctors have patients (especially IVF patients) take oral meds (letrozole or Clomid) and injectable meds in the same cycle. You may see this referred to as a combo cycle or a hybrid cycle.
If you’re curious about this option, head over to my post What is a Combo Infertility Cycle?
Summary
Yes, Femara and letrozole are the same medication. Letrozole is the generic equivalent, and it should work just as well as the brand name version.
If you’re reading this because you’re trying your first Femara/ letrozole cycle, I wish you the best of luck!
This post was last updated in February 2021.
I’m Jenn! Here I am with my beautiful twin boys. My pregnancy was possible thanks to fertility treatment for PCOS.
