Lower Cholesterol

• Estrogen in hormone replacement therapy and birth control pills can increase HDL (good cholesterol) and lower LDL (bad cholesterol) and triglycerides.
  
  

Prevent Osteoporosis

• Osteoporosis, which is a loss of bone mass and density, can be reduced or prevented in menopausal women by taking estrogen hormone replacement therapy.
  
  

Colon Cancer

• According to the Mayo Clinic, a positive side effect of estrogen use in postmenopausal women is a lower risk of developing colon cancer.
  
  

Reduce Menopause Symptoms

• Estrogen taken as a pill, transdermal (skin) patch or vaginal cream can reduce the symptoms of menopause such as hot flashes and vaginal dryness.
  
  

Stroke

• Side effects of estrogen in postmenopausal women include a higher risk of stroke from blood clots in the brain.
  
  

Blood Clots

• Estrogen may increase the risk of having a blood clot in the legs (deep vein thrombosis), which may be further increased in women who are smokers.
  
  

Breast Cancer

• Women who take estrogen before reaching menopause may increase their risk of developing breast cancer, according to the Mayo Clinic.