IVF involves a surprisingly long list of medications, and most people go through several categories of drugs across different phases of treatment. These range from hormone injections that stimulate egg growth to progesterone that supports early pregnancy. Here’s what each medication does, when you’ll typically take it, and what to expect.
Ovarian Stimulation: The Foundation of IVF
The first major phase of IVF is ovarian stimulation, where the goal is to grow multiple mature eggs in a single cycle instead of the one egg your body would normally produce. This is done with injectable hormones called gonadotropins, specifically follicle-stimulating hormone (FSH). Brand names you’ll commonly see include Gonal-F and Follistim, both of which contain lab-made FSH that works the same way as the hormone your pituitary gland naturally releases.
These injections are given subcutaneously, meaning just under the skin, usually in the lower abdomen. Most people self-administer them at home once or twice daily for about 8 to 14 days. Your clinic will monitor follicle growth with ultrasounds and blood work every few days, adjusting your dose based on how your ovaries are responding. Some protocols also include a medication containing both FSH and LH (luteinizing hormone) to support follicle development, particularly in women with low LH levels.
Preventing Premature Ovulation
While your ovaries are being stimulated, there’s a risk your body will trigger ovulation too early, releasing eggs before they can be retrieved. To prevent this, you’ll take one of two types of medication that suppress your body’s natural ovulation signal.
GnRH antagonists like cetrorelix (Cetrotide) or ganirelix are the more common modern approach. These are daily injections typically started around day 6 of stimulation and continued until the trigger shot. They work quickly, blocking the brain’s signal to ovulate within hours.
GnRH agonists like triptorelin or leuprolide (Lupron) take a different approach. In what’s called the “long protocol,” you start these injections about two weeks before stimulation begins. They initially cause a brief surge of hormones, then suppress your system completely, giving the clinic full control over your cycle’s timing. This protocol involves more days of injections overall but has been used successfully for decades.
Both approaches are effective. The antagonist protocol is shorter and involves fewer injections, which is why many clinics have shifted toward it as the default.
The Trigger Shot
Once your follicles reach the right size, you’ll receive a precisely timed injection called the trigger shot, which kicks off the final stage of egg maturation. Egg retrieval is then scheduled about 36 hours later. Timing matters enormously here: too early and the eggs aren’t mature, too late and ovulation has already occurred.
The traditional trigger is human chorionic gonadotropin (hCG), sold under brand names like Ovitrelle and Pregnyl. hCG mimics the natural LH surge that normally triggers ovulation, because the two hormones are structurally similar. For women on an antagonist protocol, clinics sometimes use a GnRH agonist (like leuprolide) as the trigger instead, which stimulates a more natural surge of both LH and FSH from the pituitary gland. A “dual trigger” combining both hCG and a GnRH agonist has shown improved outcomes in some patients undergoing antagonist cycles.
One major reason clinics choose a GnRH agonist trigger over hCG is to reduce the risk of ovarian hyperstimulation syndrome (OHSS), a painful and potentially serious complication where the ovaries swell and fluid leaks into the abdomen. hCG lingers in the body longer and can worsen this reaction.
Progesterone for Luteal Phase Support
After egg retrieval, your body needs progesterone to prepare the uterine lining for an embryo to implant. The retrieval process disrupts normal hormone production, so nearly every IVF patient takes supplemental progesterone starting the day of or the day after retrieval. This continues for several weeks, often through the first 8 to 12 weeks of pregnancy if the transfer is successful.
Progesterone comes in several forms, and your clinic will choose based on effectiveness, convenience, and your tolerance:
- Vaginal inserts or suppositories are the most widely used. A standard dose is 600 mg per day of micronized progesterone, split into two or three doses. They deliver the hormone directly to the uterus and are easy to self-administer, though they can be messy.
- Intramuscular injections (progesterone in oil) are injected into the upper buttock with a longer needle. They’re effective but can cause soreness, skin inflammation, and occasionally sterile abscesses at the injection site.
- Subcutaneous aqueous progesterone is a newer option that’s water-soluble and easier to inject than the oil-based version. It’s given twice daily and is more comfortable for many patients.
Oral progesterone is rarely used in IVF because the liver breaks it down too quickly, making it far less effective than vaginal or injectable forms.
Medications for Frozen Embryo Transfers
If you’re doing a frozen embryo transfer (FET) rather than a fresh transfer, you’ll follow a separate medication protocol to prepare your uterine lining. In a hormone replacement FET cycle, you take estrogen first, usually as pills, patches, or vaginal tablets, to thicken the endometrium. Your clinic monitors lining thickness and hormone levels via ultrasound and blood work.
Once the lining reaches the target thickness (typically around 7 to 8 mm), you begin progesterone to convert the lining into a receptive state. The embryo transfer is then timed to match the number of days of progesterone exposure with the embryo’s developmental stage. Some FET protocols also include a GnRH agonist injection during the luteal phase, and hCG may be added alongside progesterone and estrogen for additional support.
Priming Medications Before Stimulation
Some protocols call for medications in the weeks before stimulation begins, designed to synchronize follicle growth or improve the ovarian response.
Oral contraceptive pills are commonly prescribed for one to three weeks before a cycle. They suppress ovarian activity so that follicles start from a more uniform baseline, which can make stimulation more predictable and help with scheduling.
Testosterone gel is sometimes used as a priming agent, particularly for women with a poor ovarian response. Applied to the skin daily in the weeks before stimulation, testosterone works at the ovarian level to enhance how follicles respond to FSH. This approach essentially mimics the role that LH plays in early follicle development.
Adjuvant Medications
Depending on your medical history, your clinic may add medications that aren’t part of the standard IVF drug protocol but address specific underlying issues.
Low-dose aspirin (around 81 to 100 mg daily) is sometimes prescribed to improve blood flow to the uterus. For women with certain autoimmune antibodies who’ve had repeated IVF failures, a combination of low-dose prednisone (a steroid that dampens immune activity) and aspirin has shown a clinical pregnancy rate of about 33% per cycle, suggesting it can help in that specific population.
Metformin is occasionally added for women with polycystic ovary syndrome (PCOS) to improve insulin sensitivity and ovarian function during stimulation. It’s not universally prescribed but may help reduce the risk of OHSS in PCOS patients.
Managing Ovarian Hyperstimulation Syndrome
OHSS is one of the most significant risks of the stimulation phase, and several preventive strategies involve medication. Beyond choosing a GnRH agonist trigger instead of hCG, clinics may prescribe cabergoline, a medication that reduces blood vessel permeability in the ovaries. In one controlled trial, cabergoline cut the incidence of OHSS by about 60%, dropping it from roughly 21% in untreated high-risk women to about 8%. It’s typically taken for about a week starting on the day of egg retrieval.
Letrozole, an aromatase inhibitor that lowers estrogen levels, is another option sometimes used after retrieval to bring down estrogen quickly in women at high risk. Both medications are short-term additions rather than standard parts of every protocol.
What the Injection Schedule Looks Like
For most people, the daily reality of IVF medications means self-administering one to three injections per day during stimulation, all subcutaneous with small needles in the belly area. The stimulation phase lasts roughly 10 to 12 days. After retrieval, if you’re using injectable progesterone, that continues daily for weeks. In total, a single IVF cycle can involve anywhere from 30 to 90 individual injections, depending on the protocol and how long you need luteal support.
Most stimulation medications and GnRH antagonists come in pre-filled pens or syringes designed for home use. Intramuscular progesterone injections are the one type that many people find difficult to do alone, since they require a longer needle into the upper buttock. Partners or friends often help, or some patients visit their clinic or a nearby pharmacy for those shots.