Fulvestrant: uses, dosing, side effects & brands
Fulvestrant is an estrogen receptor antagonist sold in the U.S. under 2 brand and generic names, for breast neoplasms. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Estrogen Receptor Antagonist
- Treats (across its forms)
- Breast Neoplasms
- Available as
- Injectable · Solution
- Sold as
- 2 products — Fulvestrant and Cligavyx
- Prescription?
- Prescription only
- Generic available?
- Yes
How fulvestrant is dosed
From the FDA label for Fulvestrant (application ANDA210044). Other fulvestrant products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Fulvestrant injection 500 mg should be administered intramuscularly into the buttocks (gluteal area) slowly (1 to 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29 and once monthly thereafter. ( 2.1 , 14 ) A dose of 250 mg is recommended in patients with moderate hepatic impairment to be administered intramuscularly into the buttock (gluteal area) slowly (1 to 2 minutes) as one 5 mL injection on Days 1, 15, 29 and once monthly thereafter. ( 2.2 , 5.2 , 8.6 ) 2.1 Recommended Dose Monotherapy The recommended dose of fulvestrant injection is 500 mg to be administered intramuscularly into the buttocks (gluteal area) slowly (1 to 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29 and once monthly thereafter [see Clinical Studies (14) ]. Combination Therapy When fulvestrant injection is used in combination with palbociclib, abemaciclib, or ribociclib, the recommended dose of fulvestrant injection is 500 mg to be administered intramuscularly into the buttocks (gluteal area) slowly (1 to 2 minutes per injection) as two 5 mL injections, one in each buttock, on Days 1, 15, 29 and once monthly thereafter. When fulvestrant injection is used in combination with palbociclib, the recommended dose of palbociclib is a 125 mg capsule taken orally once daily for 21 consecutive days followed by 7 days off treatment to…
Fulvestrant side effects
The following adverse reactions are discussed in more detail in other sections of the labeling: Risk of Bleeding [see Warnings and Precautions (5.1) ]. Increased Exposure in Patients with Hepatic Impairment [see Warnings and Precautions (5.2) ]. Injection Site Reaction [see Warnings and Precautions (5.3) ]. Embryo-Fetal Toxicity [see Warnings and Precautions (5.4) ]. The most common adverse reactions occurring in ≥ 5% of patients receiving fulvestrant injection 500 mg were: injection site pain, nausea, bone pain, arthralgia, headache, back pain, fatigue, pain in extremity, hot flash, vomiting, anorexia, asthenia, musculoskeletal pain, cough, dyspnea, and constipation. ( 6.1 ) Increased hepatic enzymes (ALT, AST, ALP) occurred in > 15% of fulvestrant injection patients and were not dose-dependent. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Amneal Pharmaceuticals LLC at 1-877-835-5472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, the adverse reaction rates observed cannot be directly compared to rates in other trials and may not reflect the rates observed in clinical practice. Monotherapy Comparison of Fulvestrant 500 mg and Fulvestrant 25 0 mg (CONFIRM) The following adverse reactions (ARs) were calculated based on the safety analysis of CONFIRM comparing the…
Who shouldn’t take fulvestrant
Fulvestrant injection is contraindicated in patients with a known hypersensitivity to the drug or to any of its components. Hypersensitivity reactions, including urticaria and angioedema, have been reported in association with fulvestrant [see Adverse Reactions (6.2) ]. Hypersensitivity. ( 4 )
Fulvestrant drug interactions
There are no known drug-drug interactions. Although, fulvestrant is metabolized by CYP3A4 in vitro , drug interactions studies with ketoconazole or rifampin did not alter fulvestrant pharmacokinetics. Dose adjustment is not needed in patients co-prescribed CYP 3A4 inhibitors or inducers [see Clinical Pharmacology (12.3) ]. There are no known drug-drug interactions. ( 7 )
Every fulvestrant product we track (2)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 70/100 | Prescription | Injectable | No data | — | View → | |
| 2 | Not yet rated | Prescription | Injectable | No data | — | View → |
How long fulvestrant keeps
No fulvestrant label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does fulvestrant expire? The in-use limits and storage rules from its labelsWhat people report to the FDA about fulvestrant
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 16,528 reports naming fulvestrant, and the FDA flagged 91% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- malignant neoplasm progression2,706 reports
- fatigue1,762 reports
- neutropenia1,640 reports
- nausea1,501 reports
- metastases to bone1,418 reports
- diarrhoea1,319 reports
- breast cancer metastatic1,187 reports
- metastases to liver1,152 reports
Read these as a signal, not a rate. A report does not mean fulvestrant caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
Related calculators
Frequently asked questions
What is fulvestrant?
Fulvestrant injection for intramuscular administration is an estrogen receptor antagonist.
What kind of drug is fulvestrant?
The FDA classifies fulvestrant as an estrogen receptor antagonist. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take fulvestrant with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run fulvestrant against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is fulvestrant sold under?
We track 2 fulvestrant-containing products in the U.S.: Fulvestrant and Cligavyx. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does fulvestrant come in?
Across the brands we track, fulvestrant is currently marketed as injectable and solution, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic fulvestrant?
Yes. Our catalog lists 1 generic fulvestrant product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
Cite this page
- APA
- pharmaranks. (2026, July 24). Fulvestrant: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/fulvestrant
- MLA
- “Fulvestrant: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/fulvestrant.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for fulvestrant on DailyMed (NIH) ↗.