HCG 10,000 IU is a high-dose, injection of Human Chorionic Gonadotropin used to trigger ovulation in women (often in IVF) and to treat male hypogonadism by stimulating testosterone production. Reconstituted from powder, it is administered via intramuscular or subcutaneous injection. Common side effects include pain at the injection site, headache, irritability, and, rarely, severe ovarian hyperstimulation syndrome (OHSS).