Enlarged Breasts

• High levels of estrogen and decreasing testosterone can lead to the formation of excess breast tissue in men; this is common in boys during puberty and older men.
  
  

Breast Cancer

• Higher levels of estrogen in men may lead to a greater likelihood of developing male breast cancer.
  
  

Impotence

• Taking estrogen may lead to erectile dysfunction--the inability to attain and sustain an erection sufficient for sexual activity.
  
  

Libido

• Taking estrogen may decrease a man's sex drive and can cause the size of the testicles to decrease.
  
  

Prostate Cancer

• According to John R. Lee, M.D, estrogen dominance may also be a contributing factor toward developing prostate cancer.