In general, infertility drugs work by releasing the hormones that either initiate ovulation or regulate it. Some are taken by mouth, and others are injected.

For the injectable drugs, some are given beneath the skin (subcutaneously), and others are injected into the muscle (intramuscular). They are usually injected in the abdomen, upper arm, upper thigh, or buttocks. The injections are usually started on the second or third day of a cycle (with the first day being the first day you see bright red blood) and contined for seven to 12 consecutive days.

Clomiphene Citrate (Clomid®, Serophene®) is an anti-estrogen that acts on the brain to stimulate release of more hormones to induce ovulation. Patients take clomiphene citrate tablets by mouth during the early part of a cycle. The American Society for Reproductive Medicine (ASRM) recommends that patients use this medication for no more than six months.

Human Menopausal Gonadotropin or hMG (Repronex®, Pergonal®) contains luteinizing hormone (LH) and follicle stimulating hormone (FSH). These hormones stimulate the ovaries to produce more follicles, thus increasing the number of eggs. The medication is injected into a muscle (intramuscular--IM-- injection). Newer formulations can be injected just below the skin (subcutaneously -- SQ).

Follicle Stimulating Hormone or FSH (Gonal-F®, Follistim®, Bravelle®) stimulates ovaries to produce more follicles, thus increasing the number of eggs. FSH is injected subcutaneously.

Human Chorionic Gonadotropin or hCG (Profasi®, Ovudrel®, Pregnyl®) is a hormone that matures the developing follicles and triggers release of an egg from its follicle. In men, hCG may be used to enhance sperm production. It is taken as an intramuscular (IM) injection or subcutaneous (SQ) injection.

Progesterone is a hormone that helps prepare the endometrium (the lining of the uterus) for the arrival and implantation of an embryo. Progesterone is delivered by intramuscular injection or by vaginal suppository, capsule, gel and certain formulations can be taken by mouth.

Leuprolide Acetate (Lupron®) acts on the brain to initially stimulate and then to suppress the body's own hormone production, thus preventing follicle development and egg release. Doctors use it in combination with other medications to improve the stimulation cycle.

GnRH Antagonist (Antagon®, Cetrotide®) acts on the brain to suppress the body's own hormone production, thus preventing follicle development and egg release. It is used in combination with other medications to improve the stimulation cycle.