Key points
- Fulvestrant is two injections into the muscle (one in each buttock) given on days 1, 15 and 29 and then once a month [1].
- It is used for advanced hormone-sensitive breast cancer, alone or with palbociclib, ribociclib or abemaciclib tablets [1].
- In women after menopause, it controlled the disease longer than anastrozole [2].
What is this drug and how does it work?
Fulvestrant takes hold of the oestrogen receptor on breast cancer cells and destroys it, so the cancer can no longer grow with oestrogen [1]. It is used in women after menopause (or women whose ovaries have been switched off with medicine).
For physicians
A SERD: binds the oestrogen receptor, inhibits dimerisation and induces receptor degradation; it has no agonist activity [1].
Which cancers is it used for?
- Advanced or spread hormone receptor-positive, HER2-negative breast cancer in women after menopause [1]
- With palbociclib, ribociclib or abemaciclib after previous hormone therapy [1]
For physicians
| Disease | Use | Key evidence |
|---|---|---|
| Advanced HR+ breast cancer without prior endocrine therapy | Monotherapy [1] | FALCON: median progression-free survival 16.6 vs 13.8 months with anastrozole [2] |
| Advanced HR+ breast cancer after endocrine therapy | Alone or with a CDK4/6 inhibitor [1] | — |
How it is taken and dosing
Show detailsHide
Two 5 mL injections, one in each buttock, are given slowly (1 to 2 minutes each) at the clinic: on days 1, 15 and 29, then once a month [1].
For physicians
Standard dosing (FDA label)
Fulvestrant
Advanced HR+, HER2-negative breast cancer
Advanced HR+, HER2-negative breast cancer
| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Fulvestrant | 500 mg (two 250 mg injections) | Intramuscular, buttock | Days 1, 15, 29 and then monthly |
Moderate hepatic impairment (Child-Pugh B): 250 mg on the same schedule. Caution with thrombocytopenia or anticoagulants (intramuscular injection). Premenopausal women with a CDK4/6 inhibitor also need an LHRH agonist [1].
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Side effects
The most common side effects: pain at the injection site, nausea, bone and joint pain, headache, back pain, tiredness, hot flushes and poor appetite [1].
For physicians
Common adverse reactions (5% or more): injection-site pain, nausea, bone pain, arthralgia, headache, back pain, fatigue, pain in extremity, hot flushes, vomiting, anorexia, asthenia and cough [1].
Serious side effects
Less common serious side effects: bleeding at the injection site in people with low platelets or taking blood thinners, and sciatic nerve pain after the injection [1].
For physicians
When should I call my doctor?
- Bleeding or a lot of swelling at the injection site
- Shooting pain down the leg after the injection
- Yellowing of the skin or eyes
- New, severe bone pain
Interactions, pregnancy and precautions
- Other medicines: if you take a blood thinner (warfarin or similar), tell your doctor [1].
- Tests: fulvestrant may make an oestradiol test falsely high [1].
- Pregnancy: this drug may harm an unborn baby; use effective contraception during treatment and tell your doctor straight away if you become pregnant. Do not breastfeed during treatment [1].
Frequently asked questions
Are the injections painful?
Pain at the injection site is common but usually brief; injecting slowly helps [1].
Related cancer types
References
2 referencesShow all referencesClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2
This page is based on reputable scientific sources and was last updated on 27 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
Printed from the website; the full and up-to-date version: https://drdabiri.com/en/drugs/fulvestrant/