Raloxifene
Evista
Raloxifene (Evista) is a hormonal & sexual research compound. SERM — antagonist at breast tissue, agonist at bone. Unlike tamoxifen it's antagonist at the uterus too, which removes the endometrial cancer signal.
Raloxifene quick facts
| Reported research dose | 60mg daily |
| Route | Oral |
| Frequency | 1x |
| Half-life | ~28 hours |
| Forms | Oral |
| Evidence level | Approved for postmenopausal osteoporosis and breast-cancer risk reduction |
In this audience it comes up for gynecomastia, where the evidence is genuinely better than tamoxifen's for reducing established glandular tissue. ⚠️ Increases VTE risk — real, and it stacks with the raised hematocrit of AAS use. Not a casual purchase; needs a prescriber and a reason.
How Raloxifene works
SERM — antagonist at breast tissue, agonist at bone. Unlike tamoxifen it's antagonist at the uterus too, which removes the endometrial cancer signal.
Proposed benefits
Researched for libido, hormonal signaling and reproductive / sexual function.
Where to get Raloxifene
Buy Raloxifene at AlgoRx →The evidence for Raloxifene
Graded by what exists behind each claim.
✅ Clinically validated
- Approved for osteoporosis and breast-cancer risk reduction, with large randomized data — MORE and STAR. STAR compared it head-to-head with tamoxifen and found comparable risk reduction with fewer uterine events.
📊 Correlative data
- Used for gynecomastia, where a small published trial in adolescents reported better response than tamoxifen. Real-world use is much lower than tamoxifen's.
🧪 Theoretical / extrapolated
- A second-generation SERM — antagonist in breast and uterus, agonist in bone. The uterine antagonism is the key difference from tamoxifen and the reason for the better endometrial safety profile.
- Same class thromboembolic risk, since hepatic estrogen-receptor agonism drives it in both.
How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →
What Raloxifene actually does
A SERM is not a weak estrogen and it is not an anti-estrogen. It is the same molecule behaving oppositely in two tissues at the same time, and raloxifene is the cleanest example there is: agonist in bone and liver, antagonist in breast and uterus Hochner-Celnikier 1999. Understanding how one ligand does that is the whole page, and there is a crystal structure that shows it.
The structure. Brzozowski 1997 solved the ligand-binding domain of the estrogen receptor twice: with 17β-estradiol at 3.1 Å and with raloxifene at 2.6 Å. Both ligands occupy the same pocket in the core of the domain, but with different binding modes, and each induces a distinct conformation in the transactivation domain. That is the structural evidence for antagonism, and it is a mechanism nobody had before 1997.
What that conformational difference means, reasoned from the structure rather than asserted. Raloxifene is a benzothiophene carrying a bulky basic side chain that estradiol does not have. The core fits the pocket; the side chain does not, and has to go somewhere. Where it goes prevents the receptor's C-terminal helix from packing across the pocket in the position that completes the coactivator-binding surface. A receptor stuck in that shape still binds DNA at estrogen response elements — it simply cannot recruit the coactivators that would turn transcription on through that surface. Tissue selectivity then follows from which coactivators and corepressors a given tissue actually has. Breast and uterus, rich in the coactivators that surface recruits, see an antagonist. Bone and liver, where estrogen-responsive transcription leans on other surfaces and other partners, see an agonist.
The one clinical difference from tamoxifen falls straight out of this. Tamoxifen is a partial agonist in the endometrium; raloxifene is not Hochner-Celnikier 1999. That is not a marketing distinction, it is measured — in the head-to-head trial there were 36 uterine cancers on tamoxifen against 23 on raloxifene Vogel 2006. And the liver agonism is equally real and cuts the other way: hepatic estrogen-receptor activation drives synthesis of coagulation factors, which is the mechanistic origin of the thromboembolic risk that both drugs carry and that the raloxifene label carries in a boxed warning US Food and Drug Administration 2018. One molecule, one receptor, four tissues, four different answers.
Cell, rodent, human — and where it stops
Step one, the structure. Two crystal structures at 2.6 and 3.1 Å Brzozowski 1997. No cells, no animals — the mechanism here was solved at the atomic level before it was measured clinically, which is the reverse of almost everything else in this vault.
Step two, MORE, and it met its endpoint. Ettinger 1999 randomized 7,705 postmenopausal women with osteoporosis, aged 31 to 80 across 25 countries, to raloxifene 60 mg, 120 mg or placebo for 36 months. Vertebral fracture occurred in 10.1% on placebo, 6.6% at 60 mg and 5.4% at 120 mg — relative risk 0.7 (95% CI 0.5–0.8) and 0.5 (0.4–0.7). Femoral neck bone density rose 2.1–2.4% and spine 2.6–2.7%. Read the next two findings together, because they are the shape of this drug: non-vertebral fractures did not fall at all (RR 0.9, 0.8–1.1), and venous thromboembolism rose with a relative risk of 3.1 (1.5–6.2).
Step three, STAR, the head-to-head against tamoxifen. Vogel 2006 randomized 19,747 postmenopausal women at raised breast cancer risk (mean 5-year Gail risk 4.03%) to tamoxifen 20 mg or raloxifene 60 mg for five years. On the primary endpoint they tied: 163 versus 168 invasive breast cancers, RR 1.02 (0.82–1.28). Then the trade-offs separate, and they go in both directions. Raloxifene had more non-invasive disease — 80 versus 57, RR 1.40 (0.98–2.00) — and fewer uterine cancers (23 versus 36, RR 0.62), fewer thromboembolic events (RR 0.70, 0.54–0.91) and fewer cataracts (RR 0.79, 0.68–0.92). Note carefully: raloxifene's thromboembolic advantage in STAR is relative to tamoxifen, which is not the same as safe. Against placebo in MORE the risk tripled.
Step four, RUTH, which missed its cardiovascular endpoint and found a harm. Barrett-Connor 2006 randomized 10,101 postmenopausal women with coronary heart disease or multiple risk factors, mean age 67.5, to raloxifene 60 mg or placebo for a median of 5.6 years. Primary coronary events: 533 versus 553, hazard ratio 0.95 (0.84–1.07) — no effect. Invasive breast cancer fell (40 versus 70, HR 0.56, 0.38–0.83) and vertebral fracture fell (64 versus 97, HR 0.65, 0.47–0.89). And fatal stroke rose: 59 versus 39, HR 1.49 (1.00–2.24), an absolute increase of 0.7 per 1,000 woman-years; venous thromboembolism rose too, 103 versus 71, HR 1.44 (1.06–1.95). That fatal-stroke finding is one half of the boxed warning US Food and Drug Administration 2018.
Step five, the one study in the population that reads this site. Lawrence 2004 treated 38 consecutive adolescents (mean age 14.6) with persistent pubertal gynecomastia of mean duration 28.3 months, for 3 to 9 months. Mean breast nodule reduction was 2.5 cm on raloxifene (95% CI 1.7–3.3, p < 0.0001) against 2.1 cm on tamoxifen (1.7–2.7), and the separation is in the responder rate: a greater-than-50% decrease in 86% of raloxifene patients versus 41% on tamoxifen. No side effects were observed.
The obstacle, stated bluntly. Lawrence 2004 is a retrospective chart review of 38 boys, not randomized, not blinded, not controlled, in a condition that resolves spontaneously in a large fraction of cases — and it is the entire published evidence base for the use this compound is bought for. Everything with a hazard ratio attached to it — MORE, STAR, RUTH, more than 37,000 participants between them — was conducted in postmenopausal women, whose baseline thrombotic risk, estrogen environment and bone physiology are not those of a 25-year-old man. There is no randomized trial of raloxifene for gynecomastia in adult men, and no trial of any length in men taking androgens.
Raloxifene pharmacokinetics — how much of it actually gets in
The absorption number here is genuinely strange and it explains the dosing. About 60% of an oral dose is absorbed — and the absolute bioavailability is 2% US Food and Drug Administration 2018. That gap is not poor absorption; it is presystemic glucuronidation, and it happens largely before the drug ever reaches the liver. Kemp 2002 characterized it in vitro and attributed a major share of presystemic clearance to intestinal metabolism, with UGT1A1, UGT1A8 and UGT1A10 as the enzymes responsible. UGT1A8 and UGT1A10 are gut-wall enzymes that are barely expressed in liver at all. The gut wall, not the liver, is the gate.
What that means practically. Ninety-eight percent of the tablet becomes glucuronide before it circulates, so the 60 mg dose is large relative to the exposure achieved, and anything that changes intestinal UGT activity — a UGT1A1 polymorphism, bowel disease, resection — changes exposure disproportionately. The glucuronides then undergo enterohepatic recycling, which is why the plasma half-life is long despite the enormous first-pass loss: 27.7 hours after a single dose and 32.5 hours at steady state US Food and Drug Administration 2018. Excretion is primarily in feces, with less than 0.2% excreted unchanged in urine.
What degrades it: a conjugating enzyme, not a cytochrome. This is the point most people get wrong by analogy. Raloxifene does not have a meaningful CYP3A4 story, so the azole and grapefruit reasoning that applies to sildenafil or exemestane does not transfer. The interaction that matters is with anything that binds enterohepatically — cholestyramine reduces absorption substantially — and with the recycling loop itself.
There is no injectable raloxifene and never has been; had one existed, the 2% bioavailability figure says a parenteral dose of well under 2 mg would reproduce a 60 mg oral exposure. Nobody has built it, and the oral first-pass loss is simply accepted in the dose Hochner-Celnikier 1999.
What would have to be true, and how you would know it was not
Four predictions with markers and windows. The second is the safety one and the fourth is the one that contradicts what most people expect from a SERM.
1. Bone formation should turn on before density changes. Raloxifene is an agonist in bone, and MORE measured 2.1–2.7% gains in femoral neck and spine density over 36 months Ettinger 1999. Density is a one-to-two-year read-out; Osteocalcin is a months read-out. Baseline and 16 weeks. The mechanism predicts osteocalcin and other turnover markers fall here — raloxifene works by suppressing resorption, unlike an aromatase inhibitor, which accelerates the whole cycle. That opposite direction is the cleanest way to prove the drug is doing SERM things rather than anti-estrogen things.
2. The safety read-out is coagulation, and it belongs in the same draw. Hepatic estrogen-receptor agonism drives clotting factor synthesis; MORE measured a 3.1-fold increase in venous thromboembolism against placebo Ettinger 1999 and RUTH a hazard ratio of 1.44 Barrett-Connor 2006. D-Dimer and Fibrinogen Activity at baseline and 12 weeks will not predict a clot — no test does — but a rising fibrinogen in someone who is also running a high hematocrit on androgens is a stacking signal, and that combination is exactly the one this site's audience creates.
3. The lipid panel should improve, because the liver sees an agonist. A Lipid Panel with ApoB at baseline and 12 weeks. Hepatic estrogen-receptor agonism upregulates LDL receptor expression, so the prediction is LDL and ApoB down with HDL roughly unchanged. If LDL does not move at all, the liver is not seeing agonism, and the bone claim — which depends on the same selective-agonist logic — deserves less confidence in that person.
4. The prediction that cuts against the usual expectation: estradiol will not fall, and in a man with an intact axis it should rise. Raloxifene blocks a receptor; it does not touch aromatase. In a man it also antagonizes hypothalamic estrogen feedback, which raises LH, which raises testosterone, which raises substrate for aromatization. So Estradiol, Sensitive (LC/MS-MS) together with LH & FSH and Total Testosterone at baseline and 8 weeks should show LH up, testosterone up and estradiol up or flat — not down. Anyone using raloxifene expecting a falling estradiol number has confused a receptor blocker with an aromatase inhibitor, and this draw is what tells them.
What nobody has tested yet
There has never been a randomized trial of raloxifene for gynecomastia in adult men. Lawrence 2004 is 38 adolescents, retrospective, uncontrolled, in a condition with a high spontaneous resolution rate — and its responder split (86% versus 41% achieving a greater-than-50% reduction) is striking enough to justify the trial that has never been run. Sixty men with established gynecomastia of at least twelve months, randomized to raloxifene 60 mg, tamoxifen 20 mg or placebo for six months, with ultrasound measurement of glandular diameter rather than tape measurement, would settle the single most common real-world use of this drug. It would cost very little and nobody has done it.
Nobody has measured thrombotic risk when raloxifene is added to an already elevated hematocrit. Every thromboembolic number attached to this drug — RR 3.1 in MORE Ettinger 1999, HR 1.44 in RUTH Barrett-Connor 2006 — comes from postmenopausal women with normal red cell mass. The men most likely to take it are men on androgens, whose hematocrit is frequently above 50%. Those two risks have never been studied together, and there is no reason from first principles to expect them to be merely additive rather than multiplicative.
Nobody has tested whether the 2% bioavailability can be exploited. Sixty percent absorbed, 2% systemically available, with intestinal UGT1A8 and UGT1A10 doing the destroying Kemp 2002. A pharmacokinetic study of raloxifene given with a known intestinal UGT inhibitor, or in people genotyped for UGT1A1*28, would show whether exposure can be raised severalfold from the same tablet — which matters in both directions, because it also identifies who is unknowingly getting several times the intended dose.
Raloxifene — its own safety story, not its class's
Start with the boxed warning, because it has two halves and most summaries quote only the first. The label's boxed warning states an increased risk of deep vein thrombosis and pulmonary embolism, that women with active or past venous thromboembolism should not take it, and that an increased risk of death due to stroke occurred in a trial of postmenopausal women with documented coronary heart disease or at increased risk of major coronary events US Food and Drug Administration 2018. That second half is RUTH: 59 (1.2%) stroke deaths on raloxifene against 39 (0.8%) on placebo, or 22 versus 15 per 10,000 woman-years US Food and Drug Administration 2018 Barrett-Connor 2006.
The thrombosis number in absolute terms. The label puts the hazard ratio at 2.4 (95% CI 1.2–4.5), with roughly 1 in 100 patients developing a venous thromboembolism over an average 2.6-year exposure US Food and Drug Administration 2018. One in a hundred is not rare. The risk is front-loaded in the first few months, and it is why prolonged immobilization — long flights, surgery, a broken leg — is the specific circumstance in which the label advises stopping. Active or past DVT, pulmonary embolism or retinal vein thrombosis is a hard contraindication, as is pregnancy.
What the label explicitly does not claim. “EVISTA is not indicated for the treatment of invasive breast cancer, reduction of the risk of recurrence of breast cancer, or reduction of risk of non-invasive breast cancer” US Food and Drug Administration 2018. Those three exclusions are on the label of a drug that reduced invasive breast cancer by 44% in RUTH, and they exist because STAR found more non-invasive disease on raloxifene than on tamoxifen — 80 versus 57 Vogel 2006. A page claiming this drug prevents breast cancer full stop is contradicting the regulator that read the same trials.
The tolerability side effects are common and dull. About one in ten get hot flushes and about one in fourteen get leg cramps US Food and Drug Administration 2018. Both follow directly from antagonizing estrogen signaling where it is wanted, and both are the usual reason people stop.
The honest summary for the use this site's readers have in mind. The mechanistic case is good, the pediatric gynecomastia data is real but is 38 uncontrolled charts Lawrence 2004, and the risk column is populated with hard numbers from three trials totaling over 37,000 people — a tripling of venous thromboembolism against placebo and a fatal-stroke hazard ratio of 1.49 in an at-risk population. That asymmetry — strong evidence for the harms, thin evidence for the benefit in the intended population — is the actual shape of this compound, and it is the reason it needs a prescriber and a reason rather than a checkout button.
Sources read for this page
- Brzozowski AM, Pike AC, Dauter Z. Molecular basis of agonism and antagonism in the oestrogen receptor.. Nature 1997 · PMID 9338790
- Ettinger B, Black DM, Mitlak BH, Knickerbocker RK, Nickelsen T, Genant HK, Christiansen C, Delmas PD, Zanchetta JR, Stakkestad J, Gluer CC, Krueger K, Cohen FJ, Eckert S, Ensrud KE, Avioli LV, Lips P, Cummings SR. Reduction of vertebral fracture risk in postmenopausal women with osteoporosis treated with raloxifene: results from a 3-year randomized clinical trial. Multiple Outcomes of Raloxifene Evaluation (MORE) Investigators.. JAMA 1999 · PMID 10517716
- Vogel VG, Costantino JP, Wickerham DL. Effects of tamoxifen vs raloxifene on the risk of developing invasive breast cancer and other disease outcomes: the NSABP Study of Tamoxifen and Raloxifene (STAR) P-2 trial.. JAMA 2006 · PMID 16754727
- Barrett-Connor E, Mosca L, Collins P. Effects of raloxifene on cardiovascular events and breast cancer in postmenopausal women.. N Engl J Med 2006 · PMID 16837676
- Kemp DC, Fan PW, Stevens JC. Characterization of raloxifene glucuronidation in vitro: contribution of intestinal metabolism to presystemic clearance.. Drug Metab Dispos 2002 · PMID 12019197
- Hochner-Celnikier D. Pharmacokinetics of raloxifene and its clinical application.. Eur J Obstet Gynecol Reprod Biol 1999 · PMID 10428318
- Lawrence SE, Faught KA, Vethamuthu J, Lawson ML. Beneficial effects of raloxifene and tamoxifen in the treatment of pubertal gynecomastia.. J Pediatr 2004 · PMID 15238910
- US Food and Drug Administration. EVISTA (raloxifene hydrochloride) tablets, for oral use - full prescribing information.. FDA approved labeling, revision 2018
Raloxifene — safety, predicted from mechanism
Predicted from mechanism, not from a human safety trial. How that reasoning works →
What the mechanism predicts
Derived from the molecule, not a trial.
- Two different mechanisms with one shared consequence: less estrogen signaling. Aromatase inhibitors (anastrozole, exemestane) stop testosterone converting to estradiol; SERMs (tamoxifen, raloxifene, clomiphene, enclomiphene) block or activate the receptor depending on the tissue.
- The predicted harm is the same either way and it is not the one people expect. Estrogen is not a side effect to be eliminated — it is required for bone density, joint comfort, lipid handling, libido and mood in men as well as women. Crushing it produces aching joints, flat libido, low mood and, over years, measurable bone loss.
- Clomiphene specifically is a mixture of two isomers and the longer-lived one (zuclomiphene) accumulates; the visual disturbances reported on it are attributed to that accumulation. Enclomiphene is the isolated isomer, which is the entire argument for it.
What has actually been reported
- Well documented in oncology use: hot flushes, joint pain and reduced bone mineral density on AIs; venous thromboembolism and endometrial changes on tamoxifen.
- Visual disturbance on clomiphene is uncommon but real and is a reason to stop rather than push through.
How to reduce the risk
Same mechanism as the prediction.
- The dose almost everyone gets wrong is the AI dose. These are used in oncology to drive estradiol as close to zero as possible; that is a cancer-treatment goal and it is the wrong target for anyone else. Most people feeling terrible on a protocol are over-suppressing estradiol.
- Measure before adjusting, and measure with the sensitive (LC-MS/MS) estradiol assay — the standard immunoassay is unreliable in men and produces numbers people then medicate.
- If an AI is genuinely needed, the lowest effective dose intermittently beats a fixed daily one. Bone density is worth tracking on anything run for more than a year.
What it does to your bloodwork
A fact about the assay.
- Sensitive estradiol, total and free testosterone, LH and FSH, a lipid panel, and — for long-term use — a DEXA for bone density.
Don't run this if
- You are only using one because of a number rather than a symptom. An estradiol reading with no symptoms attached is not a reason to medicate.
The honest unknown
- Long-term outcomes of AI use in otherwise healthy men, at the doses used outside oncology, have not been studied. The bone and lipid consequences are extrapolated from populations taking them for a different reason.
Not medical advice. If you take prescription medication or have a diagnosed condition, check this with a pharmacist or doctor.
Raloxifene — interference & stacking
Predicted from mechanism, not from an interaction study. How mechanism-predicted claims are made →
What Raloxifene moves on your bloodwork
Expected direction, not a measured one.
- Complete Blood Count (CBC) with Differential — ↑ expected to rise
Hematocrit and hemoglobin rise — androgens stimulate erythropoiesis. This is the most reliably predictable movement of any compound in the Vault.
What to do: This is the number that decides whether you keep going. Baseline and every 3 months. Dehydration on the draw day inflates it, so hydrate normally or you will chase a false reading. - Total Testosterone — ↑ expected to rise
Expected. Trough vs peak matters enormously — the same protocol reads completely differently depending on when you drew.
What to do: Draw at the same point in the cycle every time or the trend is noise. - LH & FSH — ↓ expected to fall
Suppressed by negative feedback. This is the mechanism, not a side effect — and it is why exogenous androgen shuts down your own production.
What to do: Relevant if fertility matters to you. Worth knowing before, not after. - Estradiol, Sensitive (LC/MS-MS) — ↑ expected to rise
Aromatization converts a fraction to estradiol, and it rises with the androgen. Use the sensitive (LC-MS/MS) assay — the standard immunoassay is unreliable in men and produces numbers people then medicate.
What to do: If you are reading estradiol in a man, the assay choice matters more than the result. - SHBG (Sex Hormone-Binding Globulin) — ↓ expected to fall
Falls with androgen exposure, which raises the free fraction — so free testosterone can climb faster than total.
What to do: Read total and SHBG together; total alone understates what changed. - Lipid Panel (Cholesterol, HDL, LDL, Triglycerides) — ↓ expected to worsen
HDL falls, sometimes markedly. Oral 17-alpha-alkylated compounds do this far more aggressively than injectable esters.
What to do: Baseline and 12 weeks. ApoB is the better long-term read than LDL-C. - PSA (Total + Free + % Free) — ↑ expected to rise
Androgens can raise PSA modestly. It does not create prostate cancer that wasn't there, but it can unmask it.
What to do: Baseline before starting matters — without it, a later number has nothing to be compared against.
- How to work up to it, and when not to
- When to take it, and why that window
- Cycle length
- Time off between cycles
- Fasted or fed, and when in the day
- Coach Cam's personal notes
- Which compounds push the same lever, and why the dose adds up faster than people count
- What blunts it — the stacks that waste your money
- What compounds the risk, so a side effect arrives sooner than any one of them suggests
- Coach Cam's read on running it alongside the rest of your protocol
Everything above is free and stays free. Skool is where it becomes a plan — Raloxifene in an order, with the rest of what you're running.
Unlock in Skool — $10/mo →Bloodwork to run alongside Raloxifene
Baseline first, then again at 8–12 weeks.
| Marker | What it’s watching for |
|---|---|
| Total Testosterone | The baseline you can't reconstruct later |
| Free Testosterone | The fraction that does anything — total alone misleads |
| SHBG (Sex Hormone-Binding Globulin) | Explains a normal total sitting on top of a low free |
| Estradiol, Sensitive (LC/MS-MS) | The other half of the ratio, and the source of most symptoms |
| LH & FSH | Separates a testicular problem from a pituitary one |
The “Low T? Rule Out the Reversible Causes First” panel covers these in one order — 11 markers, $211.50 with the discount applied.
Check results you already have → · All 103 markers A–Z
Raloxifene — frequently asked questions
What is Raloxifene?
Raloxifene (Evista) is a hormonal & sexual research compound. SERM — antagonist at breast tissue, agonist at bone. Unlike tamoxifen it's antagonist at the uterus too, which removes the endometrial cancer signal.
Is the full Raloxifene protocol on this page?
The reported research dose is on this page, along with how Raloxifene works and the evidence behind it. The protocol — how to work up to it, frequency, cycle length, time off, what not to stack it with and Coach Cam's notes — is inside Skool.
What is the half-life of Raloxifene?
Raloxifene has an approximate half-life of ~28 hours, which is part of what determines how often it's dosed.
What's the evidence behind Raloxifene?
Current evidence level: Approved for postmenopausal osteoporosis and breast-cancer risk reduction. Raloxifene is offered for research purposes only and is not an approved medicine.
Raloxifene inside a finished plan
One arm of 2 Protocol Blueprints, free to read in full.
What Raloxifene is used for
Raloxifene appears under 2 goals in the goal router.
Related Hormonal & Sexual compounds
Where this goes next
Raloxifene is the aromatase arm of this plan. The page above is the free breakdown of one compound; the plan it belongs to — the dosing, the order to correct things in, the week-by-week schedule and what to retest — is a lesson inside Skool.