Med student here. I have been on TRT since 21. Here is what I have learned about ED, libido and horm

What I take for TRT.
I am a med student in my last year. For years I have been on TRT. Because there is just so much misinformation around, I wrote some stuff about what I have learned along the way.

What I found works best for me:

2x 50mg Test cyp per week (s.c. with 30G insulin syringe)
2x 250iu HcG (for fertility as well as steroidogenesis in the adrenals: DHEAS, preg, prog, ect.)
I experimented a lot with different doses of aromatase inhibitors, but in the end decided to not use any, because I like the effects a slightly higher estradiol has on my emotionality/personality

Libido issues are NOT the same as erectile dysfunction. Erectile dysfunction can be due to low libido (your brain is not sending signals), nerve damage (your nerves can´t conduct these signals), blood vessel dysfunction (your blood vessels can´t respond to the nerve impusles your brain has sent). In younger males, blood vessels and nerve signals work fine in most cases and ED is due to libido problems, usually because of hormonal problems. In older males ED is roughly about 50% due to libido issues and 50% due to due to blood vessel dysfunction (esp. atherosclerosis: The penis is the antenna of the heart, as one of my professor used to say), or a combination of the two.

Libido depends on a very complex interplay of multiple hormones and neurotransmitter systems. For adequate/good libido (incl. erectile function), multiple hormones need to be adequate. If just a single one of these is “off”, this will be our dealbreaker.

In general, the two most important neurotransmitters when it comes to libido is the delicate balance between dopamine and serotonin signalling. For example, dopaminergic drugs such as selegiline, amphetamine, pramipexole, ect. all have an increased libido as a “side effect”. On the other hand, serotonergic drugs (e.g. SSRIs) will reduce libido.

Multiple hormones affect these neurotransmitter systems.

Thyroid hormones: U-shaped curve. Both, very low and very high levels of thyroid hormones lead to libido issues.
Cortisol: U-shaped curve. Cortisol pretty much enhances every aspect of dopamine signaling. It increases both the number of dopamine receptors as well as how sensitive the responding cells are to the activation of these receptors.
Testosterone: The higher the better. Among other things, testosterone has very powerful effects on dopamine signalling. It also acts on many brain areas important for libido independent of dopamine (e.g. OFC, amygdala, various areas in the hypothalamus, cingulate cortices, insula).
DHT: The higher the better. Similar to testosterone it increases dopamine as well as acts on multiple other neural subpopulations important for libido regulation. What is more, DHT increases fluid secretion by the prostate gland. As the prostate gland becomes fuller, libido increases (more to that below).
Prolactin: high prolactin inhibits GnRH as well as libido directly.
Estradiol: U-shaped curve. Both very low levels and very high levels will reduce libido drastically -in fact crush it to zero. It is no coincidence that one of the major regulators of the overall serotonergic tone is in fact, estradiol.

Note: The factor that most males are most sensitive to is not a change in testosterone levels, but actually a change in estradiol levels. Even small fluctuations can have powerful effects on libido. In my opinion/experience, it is the most common problem when it comes to libido issues (given testosterone levels are not rock bottom). It is also the reason why for many males, libido improves at first after starting TRT, but over time decreases again to low levels. Next to counterregulation in dopaminergic signalling, the reason is, that because levels of estradiol increase over the first weeks of treatment as aromatase expression changes. And as levels of estradiol pass a certain threshold, libido will take a hit. Because of this, adding more testosterone often does make matters worse. In these cases, titration of the RIGHT dosage of an aromatase inhibitor is needed, but unfortunately aromatase inhibitors are highly potent molecules and just a little too much, will crush estrogen levels before any improvements in libido can be noted. Having an experienced doctor helps.

When it comes to hormones, we are all different. Some people don´t notice much change in libido, whether high or low in testosterone or estradiol, whereas for many others a change in these hormones drastically alters libido.

Furthermore, libido increases as levels of oxytocin do (although the main regulator for oxytocin expression is estradiol). a-MSH is important as well, but this is beyond the scope of this article.

One very neglected point is that libido also depends a lot on habit and psychology. Some people will have high libido even with rock bottom levels of testosterone, others will have low libido even if all hormones are optimal. My dad for example had pretty high libido, despite having had levels of free testosterone half of the lower cut-off on the medical reference range. After putting him on TRT, his libido didn´t change much. Similarly, after being castrated some males often maintain their libido for many months to years.

Solving libido issues can often be very hard because it depends on soo many factors. If just one of these factors is off, so will libido be. An experienced doctor helps, but unfortunately they are very rare. Most doctors don´t understand anything about hormones, libido regulation, psychology. They just give you Viagra/Cialis, but if your hormones are off, it is not a PDE5i what you need.

I am a medical student in my last year. I started to replace all of my major hormones starting from the age of 23. I wrote a couple of articles to share some of what I have learned, because there is just so much misinformation out there.

Note: This section about libido is part of my guide about how to replace male sex hormones (click here). In it I´ll talk in more detail about all of these things and what to do about it. Had I known then what I know now, it would have saved me lots of time, money, happiness, effort, researching and experimenting. And suffering. I hope you find value in it.


  • Glad to answer your question. I participate in the international workshop about biology last year. The topic of the workshop was about hormones too. Progesterone can indeed convert into allopregnanolone even if you inject straight progesterone. Progesterone is still progesterone after all. The effect would still be the same. However,I don't recommend overusing progresterone. Too much of it can lead to lethargy and other dangerous side affects.
  • edited August 24
    You should not experiment on your health; I am not versed in medicine, so I always listen to the doctor's recommendations. Some time ago, I had problems with potency. I decided to go to the doctor for a consultation, and he advised me to use Viagra. I decided to buy Viagra from this online pharmacy. I am ashamed to buy such drugs in regular pharmacies, so I prefer to order online. In addition, I am sure that this pharmacy provides quality pills.
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