Mythbusters: Deca-Dick

It is well known that nandrolone can cause libido problems and erectile dysfunction, there are many theories online about why this happens... thanks to science we can know the exact reason.

Explanation

First of all we have to understand who the main protagonists of this story are, the androgen receptor, DHT and DHN.

The androgen receptor, also called NR3C4x is an intracellular receptor, usually in the cytoplasm, of subfamily 3, group C, member 4 that is activated by the binding of either of the androgenic hormones testosterone or dihydrotestosterone.

Dihydrotestosterone (DHT) is an androgen, an active biological metabolite of the hormone testosterone. DHT has an affinity for the androgen receptor three times higher than testosterone and 15-30 times higher than adrenal androgens.

Dihydronandrolone (DHN) is a metabolite of nandrolone, just as DHT can and does have an affinity for the androgen receptor.

Having understood these ideas, the explanation is simple, nandrolone is broken down into metabolites, one of them is Dihydronandrolone, DHN competes to occupy the androgen receptor, displacing DHT molecules and therefore causing erection and libido problems.