An estrogen patch is applied directly to the skin, preferably near the lower abdomen, hips, or buttocks, and is changed once or twice per week. For women who have not undergone a hysterectomy, it is often suggested that they take progestin in addition to an estrogen patch in order to protect the endometrium of the uterus. Although it is uncommon, it is possible that women who have undergone a hysterectomy be recommended to take progestin as well. Transdermal estrogens are not recommended for all women; there are important precautions and side effects that should be considered before use.