Ganirelix (N-acetyl-3-(2-naphthyl)-D-alanyl-4-chloro-D-phenylalanyl-3-(3-pyridyl)-D-alanyl-L-seryl-L-tyrosyl-N9 ,N10-diethyl-D-homoarginyl-L-leucylN9 ,N10-diethyl-L-homoarginyl-L-prolyl-D-acrylamide) is a synthetic decapeptide with high antagonistic activity against naturally occurring gonadotropin-releasing hormone (GnRH). Ganirelix Acetate Injection is indicated for the inhibition of premature luteinizing hormone (LH) surges in women undergoing controlled ovarian hyperstimulation. Ganirelix is administered by a subcutaneous injection of 250 µg once per day during the mid to late follicular phase of a woman’s menstrual cycle. Treatment should start on the 5th or 6th day after the start of ovarian stimulation, and the mean duration of its use is five days. Clinical studies have shown that the most common side effect is a slight reaction at the site of injection in the form of redness, and sometimes swelling. Clinical studies have shown that, one hour after injection, the incidence of at least one moderate or severe local skin reaction per treatment cycle was 12% in 4 patients treated with Ganirelix and 25% in patients treated subcutaneously with a GnRH agonist. The local reactions generally disappear within 4 hours after administration. Other reported side effects are some that are known to be associated with ovarian hyperstimulation, including gynecological abdominal pain, headache, vaginal bleeding, nausea, and gastrointestinal abdominal pain.