Nolvadex is very well-tolerated by many individuals, particularly males.
Side effects of Nolvadex are very rarely reported in male athletes and bodybuilders using anabolic steroids.
Most side effects associated with Nolvadex are found in female breast cancer patients, and the majority of the listed potential side effects are either not seen in men or are far more pronounced in women than in men.
This is due to the significant differences in endocrine physiology between men and women, meaning the estrogen antagonist/agonist properties of Nolvadex manifest very differently in women compared to men.
Because women naturally have higher estrogen levels necessary for proper female physiological function, the impact of Nolvadex side effects is much broader and more pronounced in women than in men.
Side effects of Nolvadex in female breast cancer patients include hot flashes, vaginal itching, upset stomach, headache, dizziness, bone and joint pain, and edema.
Less common side effects in female breast cancer patients include cholesterol changes, changes in white blood cell count, changes in platelet count, skin rash, endometrial changes, deep vein thrombosis, and pulmonary embolism.
Most of the Nolvadex side effects listed above generally do not manifest in male users, who constitute almost all anabolic steroid users taking Nolvadex for any reason.
The Myth That Nolvadex Increases Progesterone Receptor Sensitivity
It is reasonable to address and dispel this commonly known myth in the Nolvadex side effects section of this profile.
For a long time, in the anabolic steroid user community, there has been a misunderstanding that Nolvadex binds to and activates progesterone receptors in breast tissue, upregulating them, leading to the misconception that it increases the likelihood of gynecomastia when using progestogenic 19-nor compounds (e.g., Nandrolone and Trenbolone, which are progestins themselves).
Subsequently, many people, mistakenly or misguidedly, advised avoiding the use of Nolvadex during cycles containing Nandrolone or Trenbolone, even if gynecomastia occurred, within the anabolic steroid user community.
Unfortunately, because people did not investigate the origin of this myth and misunderstanding, they likely failed to notice the error in understanding.
It is well-known that Nolvadex is a mixed estrogen receptor agonist/antagonist, which is thoroughly covered in this profile.
The same is not true for progesterone receptors.
Various studies have shown that Nolvadex can, and does, upregulate progesterone receptors in various tissues throughout the body, such as the endometrium (uterus) in women.
This is a generally well-known and well-documented effect of Nolvadex in women.
This occurs because the endometrium is naturally highly sensitive to estrogen, so when any substance that acts as an estrogen, like Nolvadex, acts on that tissue, the same phenomenon occurs.
This is the first part of the confusion regarding this specific myth about Nolvadex side effects.
The second part of the misunderstanding and myth lies in the fact that in breast tissue, Nolvadex acts as an estrogen antagonist, blocking estrogen receptors from binding with estrogen.
At this point, you should know this fact as common sense.
Progesterone receptors are actually upregulated in response to estrogen.
Therefore, when estrogen receptors in breast tissue are effectively blocked by Nolvadex, progesterone receptors are consequently downregulated.
The issue here lies in the fact that this phenomenon does not occur in cancer patients but does occur in healthy normal individuals.
Thus, the origin of this folklore stems from one particular study that demonstrated Nolvadex elicits an upregulation of progesterone receptors in the breast tissue of breast cancer patients [1].
The problem with this folklore lies in the interpretation of the research.
In the aforementioned study, the subjects who experienced progesterone receptor upregulation were breast cancer patients, not healthy normal individuals (and not male subjects either).
The interaction of hormones and their receptors manifests very differently in healthy normal individuals compared to breast cancer patients.
Cancer causes abnormalities in the body, leading it to exhibit very strange behaviors and processes that are different from (and sometimes the complete opposite of) normal human function, and this is a prime example.
If gynecomastia occurs as a result of using progestogenic 19-nors (e.g., Deca-Durabolin or Tren), using Nolvadex to alleviate the condition is perfectly fine and is actually recommended.
Medical References
[1] Aromatase inhibitors: cellular and molecular effects. Miller WR, Anderson TJ, White S, Larionov A, Murray J, Evans D, Krause A, Dixon JM. 2005 May;95(1-5):83-9.
