Fertility Medications Explained: What Each Drug Does and Why
A guide to the most common fertility medications and what each one does. For anyone navigating ovulation induction, IUI, or IVF treatment.
Fertility medications often come without much explanation — a prescription handed over, and you're expected to figure out the rest. This page breaks down the most commonly prescribed drugs, what each one actually does in your body, and why your doctor may have chosen it for your treatment plan.
What are the most common fertility medications?
The fertility medication toolkit covers a few main categories: oral ovulation-induction agents (letrozole and Clomid), injectable gonadotropins, the trigger shot, and progesterone support. Each works at a different point in the cycle, and which ones you take depends entirely on your treatment protocol. Metformin and GLP-1 agonists are also used in specific situations — primarily for people with PCOS or insulin resistance — though they function differently from the drugs above and serve different purposes.
What does Clomid (clomiphene) do and when is it used?
Clomid (clomiphene) was the standard of care for ovulation induction for decades. It works by blocking estrogen receptors in the brain, which prompts the pituitary to release more FSH and stimulate follicle growth. Clomid still works and is still used — but letrozole has overtaken it for most indications because of better outcomes and fewer side effects. If you're on Clomid, it's often because letrozole wasn't the right fit for your specific situation, or because it's what's available through your protocol.
What is letrozole and how is it used for fertility treatment?
Letrozole (brand name Femara) is now the first-line medication for ovulation induction — particularly for people with PCOS. It works by temporarily lowering estrogen levels, which signals your brain to produce more FSH and recruit a follicle to grow. Because it works through a different mechanism than Clomid, it generally produces better outcomes and fewer side effects for most people being treated for ovulation problems. It's typically prescribed as a 5-day course early in your cycle.
What are gonadotropin injections and when are they prescribed?
Gonadotropins — including Gonal-F, Menopur, and Follistim — are injectable hormones used when oral medications aren't producing an adequate response, or as the primary stimulation protocol during IVF and egg freezing. They're more potent than oral agents, which means they can recruit more follicles at once. That potency also means they carry a higher risk profile: multiple pregnancy and ovarian hyperstimulation syndrome (OHSS) are the two main concerns, which is why injectable cycles require close monitoring through ultrasound and bloodwork throughout the process.
What is the trigger shot and what does it do?
The trigger shot — given as either an hCG-based medication or a Lupron-based medication — matures eggs and times ovulation with precision. It's administered approximately 36 hours before either a retrieval procedure or planned timed intercourse. Timing is not approximate: the trigger shot is meant to be taken at a specific hour, not "around" that time. Your clinic will give you a precise window, and following it closely is essential to the cycle working as planned.
What are progesterone supplements used for in fertility treatment?
Progesterone supplementation is used after ovulation or an embryo transfer to support the uterine lining and help maintain an early pregnancy. It's available in three forms: vaginal suppositories, intramuscular injections, or oral capsules. The evidence suggests effectiveness is comparable across delivery forms, so the choice often comes down to tolerability and personal preference — which is worth discussing directly with your provider if one form is causing problems.
What are the side effects of fertility medications?
Side effects vary by medication class. Gonadotropins carry the highest risk profile because of their potency: the main concerns are multiple pregnancy (more than one follicle releasing) and ovarian hyperstimulation syndrome (OHSS), both of which require close monitoring to catch early. Metformin, used for insulin resistance in PCOS, is not a fertility drug itself — it improves metabolic function, which can help restore ovulation in some people with PCOS. GLP-1 agonists (such as Ozempic, Wegovy, and Mounjaro) are increasingly discussed for PCOS and metabolic health, but must be stopped before conception; data on their fertility-specific effects is still emerging.