Dienestrol is a synthetic, non-steroidal estrogen. It is an estrogen receptor agonist. Estrogens work partly by increasing a normal clear discharge from the vagina and making the vulva and urethra healthy. Using or applying an estrogen relieves or lessens: dryness and soreness in the vagina, itching, redness, or soreness of the vulva. Conditions that are treated with vaginal estrogens include a genital skin condition (vulvar atrophy), inflammation of the vagina (atrophic vaginitis), and inflammation of the urethra (atrophic urethritis).