Proviron: a DHT derivative that works mostly by moving SHBG out of the way

An old oral androgen with a mechanism that is easy to misdescribe. It is not doing much anabolically. What it is doing is competing for a binding protein, and the consequence shows up on a panel in a way that surprises people.

Binding competition, not aromatase inhibition

Established clinical use Mesterolone is a 1-methylated derivative of dihydrotestosterone. Two properties follow from that structure. It is not a substrate for aromatase, so none of it converts to oestrogen. And it binds sex hormone-binding globulin with high affinity — DHT and its derivatives bind SHBG more avidly than testosterone does.

That second property is the mechanism people usually attribute to something else. Occupying SHBG displaces testosterone from it, which raises the free fraction without raising the total, and it displaces estradiol too, which is where the anti-oestrogenic reputation comes from. It is not an aromatase inhibitor and it does not lower estradiol production; it changes how much of what is already there is bound. The SHBG page covers why that distinction changes how a panel reads.

The practical consequence for anyone reading their own bloodwork: free testosterone can rise substantially while total testosterone barely moves, and estradiol measured as a total can look unchanged while its free fraction has shifted. A panel that reports only totals will under-describe what happened.

Where it fits, and where the honest limits are

Off-label or community practice The situation it is described for is high SHBG with a good total testosterone and a poor free testosterone — a common and genuinely frustrating pattern, where raising the testosterone dose mostly raises SHBG-bound hormone. Using mesterolone there is off-label; the approvals are older and narrower than the use.

Two limits are worth stating plainly. It has little anabolic effect on its own, which the app’s own drawbacks list says, so anyone expecting a muscle effect is expecting the wrong thing. And it is an androgen, so it does suppress luteinising hormone — mildly, but it is not free of the axis effects that oral androgens have.

Being a DHT derivative also means it does what DHT does in tissues that respond to DHT: it can accelerate androgenic hair loss in people predisposed to it, and it is not suitable for women. And like most oral androgens it reduces HDL cholesterol, which is the effect that shows up on a lipid panel rather than in how someone feels.

What to measure

The app’s panel here is unusually well matched to the mechanism: free testosterone and SHBG together, because the point is the ratio between them, plus estradiol, a lipid panel for the HDL effect, and DHT. Reading total testosterone alone on this compound will tell you almost nothing.

Established clinical use Free testosterone is itself a measurement with a method problem — calculated, direct immunoassay and equilibrium dialysis give three different answers, and calculated values assume an SHBG binding behaviour this compound is deliberately interfering with. The free versus total testosterone page covers which is which. That caveat matters more here than almost anywhere.

Whether this applies to a particular person, and at what amount, is a prescribing decision made from a panel that includes SHBG. Anything on the drawbacks list below that you are experiencing belongs in front of the clinician who prescribed it.

How long one dose lasts

Try other intervals on the half-life and steady-state calculator, which runs the same function against whatever cadence you type.

The dosing rows the app records

Off-label or community practice Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.

What the app monitors alongside it

The panel below is the app’s own monitoring note for Proviron, verbatim. The analytes in it that have a page here are linked; those pages cover what each one measures, which assay produced it and how to read a trend.

• Sensitive versus standard estradiol
• Free versus total testosterone, and the three ways labs get the free number
• SHBG
• Hematocrit on testosterone therapy
• DHT (dihydrotestosterone)

Drawbacks and risks the app records

From the app’s own entry. The lipid item is the one that shows up on paper rather than in symptoms, which makes it the one worth actually measuring.

• Can accelerate male pattern baldness
• Not suitable for females
• Mildly suppresses LH
• Reduces HDL cholesterol
• Minimal anabolic effect alone
• Oral dosing requires consistency

Questions people actually ask

Does it lower estradiol?

Not by reducing production. It displaces estradiol from SHBG, which changes the bound and free fractions rather than the total made. That is a different intervention from an aromatase inhibitor and it should not be substituted for one on the assumption they do the same thing.

Why did my free testosterone rise but not my total?

That is the expected result. Occupying SHBG frees testosterone that was already circulating bound. Nothing new was produced, so the total is unchanged.

Is calculated free testosterone still valid on it?

Less so. Calculated free testosterone assumes normal binding behaviour, and this compound is competing for the binding protein. Equilibrium dialysis is the method that does not make that assumption — the free versus total page covers the difference.

Does it suppress natural production?

Mildly. It is an androgen and it does feed back on luteinising hormone, which the app’s own drawbacks list notes. It is not exempt from the axis effects other androgens have.

Where the load-bearing numbers come from

Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.