Side effects of trestolone include low estrogen levels and associated symptoms such as reduced sexual function and decreased bone mineral density among others. Trestolone is an AAS, and hence is an agonist of the androgen receptor, the biological target of androgens like testosterone. It is also a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. Due to its androgenic and progestogenic activity, trestolone has antigonadotropic effects. These effects result in reversible suppression of sperm production and are responsible for the contraceptive effects of trestolone in men.