Tamoxifen_Dosage, benefits & legal status
Also known as tamoxifen citrate, Nolvadex, Soltamox, Nolva
A breast cancer drug with a boxed warning, sold as a gyno fix.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Tamoxifen?
Plain language first. The technical label stays, but it never stands alone.Overview
It blocks estrogen where breast tissue would respond to it, which is why it is used against breast cancer and against breast tissue growth in men.
Tamoxifen is a selective estrogen receptor modulator that blocks estrogen in breast tissue while acting like estrogen in bone and the uterus.
What it's used for
A long-established breast cancer drug used on the research market to prevent or reverse breast tissue growth in men.
How does Tamoxifen work?
What it does in the body, and where.Tamoxifen does not lower estrogen. It changes what estrogen is able to do, and the answer differs by tissue.
- 01It occupies the estrogen receptorCirculating estrogen is unchanged. The receptor is what is blocked.
- 02In breast tissue it acts as an antagonistThis is the effect people are after, whether against a tumor or against breast tissue growth in men.
- 03In the uterus and bone it acts more like estrogenThe bone effect is protective. The uterine effect is why the boxed warning names endometrial cancer and uterine sarcoma.
- 04It also raises clotting riskStroke and pulmonary embolism sit in the boxed warning alongside uterine cancer.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each use below carries its own evidence level. Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
The published record
Papers and trials about Tamoxifen
383 papers tagged human · 245 not reviews or lab · 51 clinical trial publications
684 registered trials · 19 with posted results
Furthest stage reached: Approved in the US
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Prohibited at all times, in and out of competition. S4.2 Anti-estrogenic substances (tamoxifen named). Specified Substance.RegulatorsCounted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. 501 papers and 100 trials indexed in detail.
At a glance
Four things to know about Tamoxifen
Evidence
FDA-approved
Category
Sexual and hormonal
Common vial
Varies
Half-life
5 to 7 days
How much, and do you cycle it?
The range, and whether you take breaks.20 up to 40 mg per day, daily. Continuous, for years at a time in the trials FDA label
The risk-reduction indication runs 20 mg daily for five years without a break, and the adjuvant use runs for years. Nothing in the evidence base supports the short on-and-off courses used after an anabolic cycle, and nothing in it measures what those courses do.
5 to 7 daysFDA label
Tamoxifen itself declines in two phases with a terminal half-life of 5 to 7 days. Its main metabolite, N-desmethyl tamoxifen, runs about 14 days, which is why steady state takes 4 weeks for the parent and 8 weeks for the metabolite.
Source: Nolvadex label, Clinical Pharmacology
You can compare this against the whole library to see where it sits.
What does it cost?
Typical dose and cost, in plain numbers.Tamoxifen is not injected
It is taken by mouth (oral). The label uses 20 to 40 mg daily depending on the indication, with 20 mg daily for five years in the risk-reduction setting, and doses above 20 mg split into a morning and evening dose. The doses used against gynecomastia sit inside this range but the indication does not exist on the label.
Tamoxifen starts at $29.97 across 4 vendors, typically $5.50 per mg.
5 listings, last read Oct 10, 2026. Shipping and card fees are not included.
How do you store it?
Before mixing, and after.Room temperature. Cool, dry, out of light.
Tamoxifen is taken as a pill or capsule. Keep it in its original container at room temperature, away from heat, humidity, and direct sun. No fridge or mixing needed. Check the expiration date on the bottle.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Taking warfarin, if the reason for treatment is breast cancer risk reduction
- A history of deep vein thrombosis or pulmonary embolism, in the same setting
- Pregnancy
- Known hypersensitivity to tamoxifen
- Banned in drug-tested sport
Stop and get help
- Sudden shortness of breath, chest pain, or swelling and pain in one leg
- Weakness or numbness on one side, trouble speaking, or a sudden severe headache
- Abnormal vaginal bleeding, in anyone with a uterus
- Yellowing of the skin or eyes
- Signs of an allergic reaction such as face or throat swelling, hives, or trouble breathing
Common effects
- Hot flushes
- Fluid retention
- Nausea
- Mood changes
- Reduced libido
- Changes in vision, including cataract formation over time
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Tamoxifen approved?
And where the numbers on this page come from.Yes. Tamoxifen is FDA approved and available on prescription in the United States.
- Approval statusFDA-approved
- RouteBy mouth (oral)
- Checked24 August 2026
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
First approved in the US in 1977. The label carries a boxed warning: serious, life-threatening and fatal events including uterine cancer, stroke and pulmonary embolism, applied to women taking it to reduce breast cancer risk or after DCIS. In the NSABP P-1 prevention trial the rate of endometrial adenocarcinoma was 2.20 per 1,000 women-years against 0.71 on placebo, and pulmonary embolism 0.75 against 0.25. In that same risk-reduction setting the label makes it a contraindication to take warfarin or to have a history of deep vein thrombosis or pulmonary embolism. Prohibited in sport at all times by WADA under section S4.
What regulators say
From official documentsProhibited at all times, in and out of competition. S4.2 Anti-estrogenic substances (tamoxifen named). Specified Substance.
Checked 12 September 2026WADA: The 2026 Prohibited List (in force 1 January 2026)
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
What else is like Tamoxifen?
Others in Sexual and hormonal, side by side.If you're weighing Tamoxifen, it's worth reading TRH (Protirelin), Letrozole, and Cabergoline in the same class.
A breast cancer drug with a boxed warning, sold as a gyno fix.
- Dose
- 20 up to 40 mg per day
- How often
- Daily
The brain hormone behind a discontinued thyroid test, often sold under the wrong name.
- Dose
- Set by the label
- How often
- Once, for a test
The stronger aromatase inhibitor, and the one with the clearest bone cost.
- Dose
- 2.5 mg per day
- How often
- Daily
A prolactin drug whose label asks for an echocardiogram before the first dose.
- Dose
- 0.25 up to 1 mg per dose, twice a week
- How often
- Twice a week
Guides for this compound
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Soltamox prescribing information, DailyMed(2025)Boxed warning text, 1977 initial US approval, NSABP P-1 event rates and contraindications.
- Soltamox label PDF, FDA Drugs@FDA(2019)Initial US approval 1977 and the full boxed warning.
Beyond these, 601 records are indexed. Browse the records