SARMs

S23

A male contraceptive finding in rats, given by injection

7 sections

Top of article
What it actually is
What it is supposed to do
What people take it for
The dose question
How to check you have the right molecule
What people get wrong
What is known about harm

What circulates: I found no dosing figure I could trace to a source
What was studied: Nothing in a person
The gap: No published human dose to compare against
How long it lasts: I could not find one in a person.

What it actually is

S23 is a non-steroidal compound acting on the androgen receptor, with no human trial record the searches behind the class page found. It is sold on a result from rats: that it suppressed sperm production completely and reversibly, which gets described as a male contraceptive finding.

What it is supposed to do

It binds the androgen receptor with high affinity and behaves as a full agonist in cell work. The contraceptive effect follows from suppressing the brain's signal to the testes, which is what a strong androgen does.

What people take it for

Muscle gain, and hardness or dryness of appearance. The contraceptive finding is cited as evidence of potency rather than as the reason for taking it.

The dose question

What circulates: I found no dosing figure I could trace to a source
What was studied: Nothing in a person; Rat work, injected under the skin, not swallowed

No studied dose to compare

There is nothing to compare against, and the headline finding does not transfer the way the selling implies. The contraceptive result people cite gave S-23 to rats by injection under the skin together with estradiol benzoate, with four of six rendered azoospermic, no pregnancies, and full reversal at 100 days. Every efficacy figure this compound has comes from that kind of experiment. The searches behind this page found no study giving it by mouth, which is how it is sold.

Reported because it is what people use. Nothing here recommends any amount.

How long it lasts

I could not find one in a person.

Route studied

Rats, injected under the skin. That is the route behind every efficacy figure this compound has.

Route used

By mouth, which is how it is sold. The searches behind the class page found no study giving it that way.

How to check you have the right molecule

S23 and S-23 are the same name. Anti-doping names it among the SARMs at section S1.2, so a positive test is not ambiguous.

Walked through on two real certificates in how to read a certificate of analysis.

What people get wrong

The contraceptive study is quoted as though it were about S-23 by itself and about people. It gave S-23 to rats together with estradiol benzoate, by injection under the skin. Four of six were rendered azoospermic, no pregnancies resulted, and fertility returned completely by 100 days. Every part of that sentence, the species, the co-administered hormone and the route, has to travel with the finding.

What is known about harm

No published case report names S-23 on its own. It appears in combination cases and in adverse event database counts. The absence of a human record is not a safety finding, it is an absence.

Others in SARMs

Everything on this page is a summary. The citations, the studies and the reasoning live in the full entry.

Read the full entry on S23

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