This steroid displays significant binding affinity for the progesterone receptor (slightly stronger than progesterone itself). The side effects associated with progesterone are similar to those of estrogen, including negative feedback inhibition of testosterone production and enhanced rate of fat storage. Although classified as an anabolic steroid, trenbolone is sufficiently androgenic. Androgenic side effects are still common with this substance, and may include bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic steroids may also aggravate male pattern hair loss.