Femara (Letrozole): What It Is and What to Expect

Femara is the brand name. Letrozole is the generic name. It blocks aromatase, the enzyme that builds estrogen out of other hormones in fat, muscle and skin.

That mechanism explains a hard limit. Before menopause the ovaries make estrogen directly, and blocking aromatase does not stop them. So the label covers postmenopausal women. Letrozole is sometimes used before menopause, but only alongside treatment that shuts the ovaries down, and that is a decision for your oncologist rather than something the label describes.

The usual amount is one 2.5 mg tablet a day, with or without food; with severe liver disease the label drops that to one tablet every other day. Take it exactly as your own prescription and pharmacy label say. If those disagree with this paragraph, ring your team rather than adjusting anything yourself.

The label describes three points in care, all for hormone receptor positive disease.

• After surgery for early breast cancer, as the main hormone treatment.
• After 5 years of tamoxifen, as extended treatment for early breast cancer.
• For advanced or metastatic breast cancer, as first treatment, or after an anti-estrogen has stopped working.

Letrozole is also given with newer targeted tablets in advanced disease, which is why a Femara and ribociclib co-pack exists.

Aching joints, stiffness that is worst first thing in the morning, and sore muscles are the complaints that come up most. For some women it is mild. For others it is the reason they want to stop.

That is worth naming, because stopping early is common and it lowers the benefit. Options exist: exercise that keeps joints moving, timing the tablet at night, simple painkillers, or switching to a different aromatase inhibitor or to tamoxifen. Tell your team the pain is a problem before you decide on your own to stop.

Estrogen protects bone, so lowering it thins bone over time. The label reports falls in bone mineral density and suggests monitoring it. Many teams arrange a baseline DEXA scan and repeat it during treatment.

Practical steps: enough calcium and vitamin D, weight-bearing exercise, no smoking. Some women are prescribed a bone-strengthening drug. Cholesterol can also rise, so that is usually checked as well.

Treatment often runs for 5 years or longer, and taking it consistently is what delivers the benefit. Tiredness, dizziness and sleepiness are listed on the label, so take care driving until you know how it affects you. Hot flushes and night sweats are common early on and often ease.

If you have missed doses, say so honestly. Your team would rather solve the reason than assume you are taking it.

• Call 911 or go to an emergency department if a fall or even a minor stumble leaves you unable to weight-bear, or your hip, wrist or back is suddenly and severely painful. Thinning bone means fractures can happen with little force.
• Call your care team within a day or two if joint or muscle pain is bad enough that you are thinking of stopping the tablets, or if dizziness or sleepiness is making driving feel unsafe.

There is no need to wait for a review appointment to raise either of these. Both usually have a fix.

https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=82b77d74-085f-45ac-a7dd-1f5c038bf406

https://www.cancer.gov/about-cancer/treatment/drugs/letrozole