The Oxandrolone hormone does not carry any estrogenic related side effects. It does not aromatize and cannot lead to gynecomastia or water retention due to increases in estrogen levels. It further carries no progestin related activity, which again supports no estrogenic related side effects. Due to water retention being impossible with this steroid, this will decrease the risk of high blood pressure. Excess water retention can promote high blood pressure. Some steroids that do not aromatize can lead to high blood pressure, such as Trenbolone , but Anavar is rarely associated with this trait.
Flutamide acts as a selective, competitive , silent antagonist of the androgen receptor (AR).  Its active metabolite , 2-hydroxyflutamide , has between 10- to 25-fold higher affinity for the AR than does flutamide, and hence is a more powerful antiandrogen in comparison.     However, at high concentrations, unlike flutamide, 2-hydroxyflutamide is able to weakly activate the AR.   Flutamide has far lower affinity for the AR than do steroidal antiandrogens like spironolactone and cyproterone acetate, and it is a relatively weak antiandrogen in terms of potency by weight, but the large dosages at which flutamide is used appear to compensate for this.  In accordance with its selectivity for the AR, flutamide possesses no progestogenic , (direct) estrogenic , glucocorticoid , or antigonadotropic activity.   Similarly to nilutamide, bicalutamide, and enzalutamide , flutamide crosses the blood-brain-barrier and exerts central antiandrogen actions.