The Prolactin Gyno Conundrum, or not?

“I’m beginning my next cycle and I want to include Deca or Tren this time. Should I add in Caber or Prami at the start or should I just keep it on hand? I really don’t want to get prolactin gyno! Thanks.”

This is one of the most common questions a user asks when it comes to Gyno a user often experiences when using a 19-nor steroid compound; gyno that they do not normally experience with other steroids such as testosterone only cycles. Most commonly used in this 19-nor category is Deca and Trenbolone. Now, before I go into a deeper explanation from both a clinical and scientific point of view, let me just say that I have been at both ends of the spectrum as far as believing or not believing prolactin induced gyno exists. I must warn you, this read may go over the head of some and although I have simplified this text for the layman without citations and references posted all over the place (that only few are going to be able to interpret accurately), I can only do so much. So apologies in advance for any of those who this text confuses, but be sure I will answer any questions in the comments sections below when I get a chance. Now onward to the explanation.

Most certainly an academic will tell you that there is no clear, human evidence that Trenbolone and/or Deca will induce increased prolactin in the absence of estrogen or other ‘estrogen-like’ metabolites that are a result of aromatisation. I hate to break it to anyone else that believed opposite, but this is true. I urge anyone to send me a copy of their blood work that demonstrates their prolactin is far outside of reference ranges when estrogen is not. Estrogen and prolactin correlate directly proportional to one another in this context. When estrogen goes up, so too does prolactin and same on the way down. This of course is under normal circumstances in the absence of any other conditions or medications that could affect prolactin levels. Initially then after this realisation, coaches with a scientific sense [including me at the time] would say:

“Control the estrogen, which then controls the prolactin, which then controls the gyno, which then mitigates the need for Caber or Prami right? Well, yes and no.

It seems increased prolactin levels are associated with gynecomastia, but it is unclear from any research available whether or not prolactin on its own is the cause or whether or not the prolactin contributes to gyno formation in the presence of elevated or decreased levels of other hormones. Under most settings, it is difficult in humans to single out one particular hormone and assess whether or not it is the cause of a particular condition or not. This is because hormones work in a symbiotic fashion; which means they work together in harmony. It is rarely a one or two dimensional operation. Every hormone has a role to play that affects the next hormone, which then can affect the next after that. When you break that harmony, there can be consequences. More importantly right now in this explanation, is that Deca does not seem to be responsible for increased levels of prolactin any more than high doses of testosterone would be responsible because we have established that when estrogen goes up, as too does prolactin. Now Trenbolone does not aromatise at all, so what is going on here? Well, the real answer is that we really do not know for sure because most of the research available is not in the right context which is in well controlled, human trials with large enough study groups to draw accurate conclusions.

But anyway I heard someone say the words Progestin and Progesterone with Trenbolone and Deca and a possible link to gyno? Hmm, also unclear but there may be something to it. At least in the studies it seems unlikely, but we really cannot draw a clinical (real life) conclusion from an animal study. So who knows?

Now, we know from the literature that increased levels of IGF-1 with high estrogen can cause gyno. That is a fact in humans. Trenbolone and Deca in animal research seem to have the potential to increase IGF-1 too, but to a clinically significant amount in humans to contribute to gyno? Hmm, also unclear but there may be something to it.

Then we read that Trenbolone in this one animal study seems to show the potential to increase prolactin levels via an indirect route; by thyroid hormones being supressed. But hmm, unclear if the same occurs in humans? Then if it does occur in humans, to a clinically significant degree?

Then Caber itself as a medication is also seen to reduce IGF-1 levels. Could that be an indirect cure for some of these gyno cases? Or can Caber really reduce IGF-1 low enough in this context? Hmm, we don’t really know.

I hope you can all see what I am getting at here. Not only does this not seem to be a prolactin gyno conundrum related to 19-nor steroids, it seems to be a largely an unknown one as far as a clear cause goes. We call this idiopathic gynecomastia. A cause of gynecomastia that is unknown by any clear diagnostic methods or evidence.

“Okay, so Trenbolone and Deca do not seem to cause direct rises in prolactin or progesterone and it is unlikely that the cause of this gyno is anything but excessive aromatisation from the cycle itself and nothing directly related to these 19-nor steroids? Why then does Caber or Prami solve my gyno then when all else fails then huh? Because I KNOW that I do not experience gyno on any other steroids and I KNOW increasing my aromatise inhibitor dose does not work, but adding Prami or Caber does work. Explain that to me then doc?”

“So take the Caber or Prami then.” That is my response.

Despite my life being viewed from a scientific lens and despite the fact we should usually always require evidence before prescribing, it seems that when it comes to the topic of anabolic and androgenic steroids, we will never see these well controlled human trials because there will never be the ethics to conduct such studies. We could sit here all day long and do our best to extrapolate from animal and petri dish studies to form conclusions, which as any scientist knows is “worthless” without human follow up. Or, we could realise that most users only care about how to cure this gyno! So, back to my response. Take the Caber or Prami then. Increase your aromatise inhibitor dose. Try some nolva. Trial and error! That is what we are essentially left with when the blood work is not giving us a clear picture of what is actually going on. If the benefit to cost ratio weighs up, meaning it is of no real harm to try these medications to see if it works, then why not try them? Try some Caber at 0.5 mg twice a week. What is the worst that could happen? These are relatively safe experiments we could all try. The most harm done will come to your wallet and nothing more. But hey, better than having to pay several thousand dollars for a breast reduction surgery that you may have been able to prevent. It’s okay not to have all the answers and be a mechanic sometimes instead of a scientist. Sometimes the “bros” in the community really are more valuable than the medical professionals. It helps to see both sides in this sport. Not all science is good science as well. In fact, most is not. Most studies we have available are not worth applying to our daily lives. Remember that context is important and to forever practice professional scepticism.


I hope this helps! Any specific questions related to this post do not hesitate to ask in the comments section below or email us at
– Dave from

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