Also known by the trade names of "Clomid" and "Serophene," it is a synthetic estrogen hormone that is commonly used for ovulation induction. It comes in 50 mg tablets that are taken by mouth once a day for 5 days in the early part of the menstrual cycle. Due to its anti estrogenic actions, some of its side effects include thickening of the cervical mucus and thinning of the endometrial lining. The former can interfere with normal passage of sperm through the cervix to reach the egg, and the latter with implantation. Some women may complain of hot flashes (10%), nausea and/or breast discomfort (2-5%). Visual symptoms (blurring) rarely occur (<1.5%) but are an indication to discontinue therapy.