Quoted from 2 different source:
"Of great interest is that Nolvadex is an estrogen agonist in the liver, capable of activating the estrogen receptor and mimicking the actions of this sex hormone in this region of the body. As such it can have a markedly positive impact on HDL (good) cholesterol values as does estrogen. Man similarly use this drug to counter some of the negative consequences of steroid use in regards to cholesterol values and cardiac risk, as steroids often suppress HDL and raise LDL levels considerably. In some instances I have heard an athlete being able to maintain very favorable HDL/LDL cholesterol ratio, to spite the use of a moderate dosage of (400mg weekly) of an injectable like testosterone or nandrolone. It would probably be foolish to think however that Nolvadex would be a sufficient remedy with the heavy use of c-17alpha alkylated orals or extremely high dosed cycles in general.
The side effects of Nolvadex are usually low in dosages of up to 30 mg/day. In rare cases nausea, vomiting, hot flashes, numbness, and blurred vision can occur. A very rare but all the more serious problem of Nolvadex is that, in some cases it does not lower the estrogen level but can increase it. Another disadvantage is that it can weaken the anabolic effect of some steroids. It has been reported by many that Nolvadex seems to slightly reduce to gains made during a steroid cycle. It appears that many androgenic/anabolic steroids will exhibit their most powerful anabolic effect when accompanied by a sufficient level of estrogen. This may be one reason why gains made with a strong androgen like testosterone are usually much more pronounced than when using an anabolic that aromatizes to a lower degree. It therefore seems like good advice to be aware of how much Nolvadex is actually needed before committing to it during a cycle. Many people in fact find it unnecessary, even when utilizing problematic compounds such as testosterone of Dianabol. Others however find they are trouble by water retention and gynecomastia, even with milder anabolics like Deca and Equipoise. The estrogenic response to steroid use is very individual and may be influenced by factors such as age and body fat percentage."
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