Is cetrorelix FDA-approved, and what does the research show?

What is cetrorelix?

Cetrorelix is a man-made version of a natural hormone, changed so that it blocks the hormone's receptor instead of switching it on ¹. The natural hormone is GnRH (gonadotropin-releasing hormone), which makes the pituitary gland release two others, LH (luteinizing hormone) and FSH (follicle-stimulating hormone) ¹. The label calls cetrorelix "a synthetic decapeptide," a chain of ten amino acids, and "an analog of native GnRH" with five of the ten positions changed ¹. It is sold as Cetrotide and is given by injection under the skin ¹.

Cetrorelix is not a wellness, weight-loss or performance peptide. It is a prescription fertility drug with one approved use, inside a cycle of assisted reproduction such as IVF ¹. In such a cycle, daily hormone injections called gonadotropins make a group of follicles grow, the sacs in the ovary where eggs mature ¹. The eggs are then collected and fertilized outside the body, and an embryo is transferred to the womb ¹. The first stage, the hormone injections, is called controlled ovarian stimulation ¹.

Is cetrorelix FDA-approved?

Yes, as a prescription drug for one use in fertility treatment. FDA approved Cetrotide (cetrorelix acetate for injection) on August 11, 2000, under new drug application (NDA) 021197, held by EMD Serono ². The label is marked "Rx only" ¹.

The label gives one indication: "the inhibition of premature LH surges in women undergoing controlled ovarian stimulation" ¹. An LH surge is the mid-cycle rise in luteinizing hormone that makes the ovary release an egg ¹. If the surge comes too early during stimulation, so does ovulation ¹. The patient leaflet says premature ovulation "may lead to eggs that are not suitable for fertilization" ¹. The label says cetrorelix "should be prescribed by physicians who are experienced in fertility treatment" ¹.

Drugs@FDA, the agency's database of approved drugs, lists two Cetrotide products under that application ². As of November 9, 2026, the date of the record's data, the lower-strength vial has the marketing status "Prescription" and the higher-strength vial "Discontinued" ². The label is headed with the lower strength, and its dosing and supply sections give only that strength ¹. Its sections on the drug's action and on the trials still describe the higher strength ¹.

Drugs@FDA also lists six generic cetrorelix acetate products from other companies, approved between August 2022 and April 2026 ⁶. As of the same data date, November 9, 2026, five have the marketing status "Prescription" and one "Discontinued" ⁶.

See the FDA status of every peptide, updated weekly.

How does cetrorelix work?

In a natural cycle, GnRH prompts cells in the pituitary to make and release LH and FSH ¹. At mid-cycle, a rise in the hormone estradiol feeds back on this system and produces the LH surge ¹.

Cetrorelix "competes with natural GnRH for binding to membrane receptors on pituitary cells," which holds back the release of LH and, less strongly, of FSH ¹. At the doses used during ovarian stimulation, though, the label says FSH levels are not affected ¹. LH starts to fall within about one to two hours, depending on the dose ¹. The label found no opening burst of either hormone, which it reads as the mark of an antagonist, a drug that occupies a receptor without activating it ¹. In women, cetrorelix "delays the LH-surge, and consequently ovulation," and its effects on LH and FSH reverse after treatment stops ¹.

The older drugs for the same task are the GnRH agonists, such as leuprolide, whose label says it causes "an initial stimulation followed by a prolonged suppression of pituitary gonadotropins" ⁴, ⁵. A Cochrane review, a formal pooling of published trials, said in 2016 that antagonists prevent the surge "without the hypo-oestrogenic side-effects, flare-up, or long down-regulation period associated with agonists" ⁴. By "hypo-oestrogenic" the review means low in estrogen. The flare-up is the "initial stimulation" in the words of leuprolide's label, and the down-regulation the "prolonged suppression" that follows ⁵.

Antagonists, the review says, "directly and rapidly inhibit gonadotrophin release within several hours through competitive binding to pituitary GnRH receptors" ⁴. The review's "gonadotrophin" is gonadotropin, the hormone family of LH and FSH, to which the stimulation injections also belong ¹.

Ganirelix, a second GnRH antagonist that has its own page in this library, carries an FDA label for the same purpose ⁷. Degarelix (Firmagon), a GnRH receptor antagonist approved for advanced prostate cancer, also has its own page ⁸.

What does the research show?

The label describes five clinical trials of cetrorelix ¹. Two were phase 2 studies, smaller trials used to find the dose, and three were phase 3 studies, the larger trials that come before an approval ¹. In the five, 732 women were treated with cetrorelix ¹. They were 19 to 40 years old, with a mean age of 32, and 95.5 percent were "Caucasian," in the label's word ¹.

The trials excluded women with polycystic ovary syndrome, a hormone disorder of the ovaries, and women with low or no ovarian reserve, meaning few eggs left ¹. They also excluded women with stage III to IV endometriosis, the more advanced grades of a disease in which womb-lining tissue grows outside the womb ¹.

Two regimens were tested, the higher strength given once in a cycle and the lower strength given every day ¹. Each was tested in a phase 3 study with "active comparators," meaning other drugs and not a placebo, a dummy injection ¹. The label calls both studies "adequate and well controlled" ¹. A third phase 3 study gave the daily regimen with no comparison group ¹.

The outcome was a premature LH surge after cetrorelix was started, defined by set blood levels of LH and progesterone ¹. No surge occurred among the 115 women given the single dose ¹. In the two daily-regimen studies, a surge occurred in 1.9 percent of 159 women and in 1.0 percent of 303 women ¹. The label gives these figures for the cetrorelix groups only, with no result for the comparator drugs ¹.

The clinical pregnancy rate per attempt, in the label's terms, was 22.6 percent, 20.8 percent and 19.8 percent in the same three groups ¹. The label does not define either term ¹. Across all five trials, 184 pregnancies were reported among the 732 women, 21 of them after frozen-thawed embryos were replaced ¹.

Studied in people: a randomized trial, in which chance decides who gets which drug, compared the single-dose regimen with an agonist ⁹. It ran at several centers and was published in February 2000 ⁹. It gave 115 women one dose of cetrorelix late in the follicular phase, the part of the cycle before ovulation ⁹. Another 39 women received a depot, a long-acting injection, of the GnRH agonist triptorelin ⁹, ¹⁰. No LH surge occurred after cetrorelix ⁹.

The cetrorelix group had fewer oocytes, the egg cells collected, and fewer embryos ⁹. The share of mature oocytes and the fertilization rates were similar, and pregnancy rates "were not statistically different" ⁹. Stimulation was shorter and used fewer ampules of the stimulating hormone in the cetrorelix group, and ovarian hyperstimulation syndrome (OHSS) occurred less often ⁹. OHSS is a complication the label ties to an excessive response of the ovaries to gonadotropins ¹. The trial's abstract gives these differences without figures by arm ⁹.

A second randomized trial, a European phase 3 study published in March 2000, gave 188 women cetrorelix and 85 women the agonist buserelin ¹¹. In it, 181 women on cetrorelix (96.3 percent) and 77 on buserelin (90.6 percent) reached the day of the hCG injection ¹¹. The hormone hCG (human chorionic gonadotropin) is given at the end of stimulation to complete the eggs' maturation ¹. A rise in LH and progesterone was seen in 3 of the 188 women on cetrorelix, or 1.6 percent ¹¹.

The cetrorelix group had fewer days of stimulation and used fewer ampules of hormone, differences unlikely to be chance (P < 0.01) ¹¹. The abstract reports "similar results" for fertilization and pregnancy rates in the two groups, without figures ¹¹. FDA's review of the application counts this trial's 188 women on cetrorelix as 159 after excluding one site, Glasgow, from the efficacy analysis ³.

The widest view is of the drug class, and the review's abstract does not report cetrorelix separately ⁴. The Cochrane review, published online April 29, 2016, included 73 randomized trials with 12,212 participants, with evidence current to April 28, 2015 ⁴. The trials compared GnRH antagonists with long-course agonist protocols, and the review rated the evidence as moderate quality ⁴. For live birth it found "no conclusive evidence of a difference" between the two (odds ratio 1.02, 95 percent confidence interval 0.85 to 1.23; 12 trials, 2,303 women) ⁴. An odds ratio of 1 means no difference, and the confidence interval is the range in which the true figure probably lies.

The authors restated it: if the chance of a live birth after an agonist is taken as 29 percent, after an antagonist it would be 25 to 33 percent ⁴. OHSS of any grade was less common with antagonists (odds ratio 0.61, 95 percent confidence interval 0.51 to 0.72; 36 trials, 7,944 women) ⁴. If the risk after an agonist is taken as 11 percent, the authors wrote, the risk after an antagonist would be between 6 and 9 percent ⁴. Miscarriage rates showed no evidence of a difference ⁴.

Fewer antagonist cycles were canceled for a high risk of OHSS (odds ratio 0.47, 0.32 to 0.69; 19 trials, 4,256 women) ⁴. More were canceled for a poor ovarian response (odds ratio 1.32, 1.06 to 1.65; 25 trials, 5,230 women) ⁴. The authors concluded, on "moderate quality evidence," that antagonist protocols are "associated with a substantial reduction in OHSS without reducing the likelihood of achieving live birth" ⁴.

The label says how the body handles cetrorelix has not been studied in people with impaired kidney or liver function, in the elderly or in children ¹. No formal drug-interaction studies have been done ¹. The label and the abstracts of the three reports give no result for body weight, muscle or athletic performance ¹, ⁹, ⁴, ¹¹.

What are the side effects?

The label's safety data come from 949 women aged 19 to 40 undergoing controlled ovarian stimulation in clinical studies, more than the 732 in its five trials ¹. FDA's review says the 949 women came from ten studies in ovarian stimulation, which include the label's five trials ³. The label lists the events reported in at least 1 percent of them "without regard to causality," that is, whether or not the drug was the cause ¹. They were OHSS of moderate or severe intensity in 33 women (3.5 percent), nausea in 12 (1.3 percent) and headache in 10 (1.1 percent) ¹. The table has no placebo or comparator column ¹.

Reactions at the injection site, such as redness, bruising, itching and swelling, were reported, and the label describes them as usually "of a transient nature, mild intensity and short duration" ¹. Blood levels of four enzymes commonly read as liver tests (ALT, AST, GGT and alkaline phosphatase) rose in 1 to 2 percent of patients ¹. The rises reached up to three times the upper limit of normal, and the label says their clinical significance "was not determined" ¹. The authors of the February 2000 single-dose trial wrote, "Tolerance of cetrorelix was excellent," but their summary gives no side-effect counts behind that judgment ⁹.

Since approval, the label says, hypersensitivity (allergic-type) reactions have been reported, "including anaphylactoid reactions with the first dose" ¹. An anaphylactoid reaction is a sudden, severe, whole-body reaction of the kind seen in serious allergy. The label also describes a "severe anaphylactic reaction associated with cough, rash, and hypotension," meaning low blood pressure, in one patient ¹. That patient had taken cetrorelix for seven months in a study unrelated to infertility, at a higher daily dose than the fertility regimen uses ¹. The label's Clinical Studies section says no drug-related allergic reactions were reported from those studies ¹.

The label also reports pregnancy outcomes ¹. Two stillbirths were reported in the phase 3 studies ¹. Clinical follow-up of 316 newborns found one twin born with anencephaly, a fatal defect of the skull and brain, who died after four days ¹. Ongoing follow-up of babies found one child with a ventricular septal defect, a heart defect, and one with congenital glaucoma in both eyes ¹.

Four pregnancies in the phase 2 and phase 3 studies ended in therapeutic abortion, a termination for medical reasons, and had major anomalies ¹. Among them were trisomy 21, which is Down syndrome, and trisomy 18, each caused by an extra copy of a chromosome ¹. The label lists further findings it calls minor: "supernumerary nipple, bilateral strabismus, imperforate hymen, congenital nevi, hemangiomata, and QT syndrome" ¹. It says the causal relationship between the reported anomalies and the drug "is unknown" ¹. IVF, gonadotropins, progesterone and other factors, it adds, "make causal attribution difficult to study" ¹.

The label's four contraindications are "Hypersensitivity to cetrorelix acetate, extrinsic peptide hormones or mannitol," "Known hypersensitivity to GnRH or any other GnRH analogs," "Known or suspected pregnancy, and lactation," and "Severe renal impairment" ¹. Mannitol is an inactive ingredient of the vial, and renal impairment is reduced kidney function ¹. Before treatment starts, "pregnancy must be excluded" ¹. In rats and rabbits the drug caused early loss of pregnancies, and the label says this "could result in fetal loss in humans as well" ¹.

The label asks for "special care" in women with active allergic conditions or a known history of allergic predisposition ¹. It says treatment "is not advised in women with severe allergic conditions" and that the drug "is not intended to be used in subjects aged 65 and over" ¹.

In sport

Cetrorelix is not named on the 2026 Prohibited List of WADA, the World Anti-Doping Agency ¹⁰. Section S2.2.1 of the list, "Testosterone-stimulating peptides in males," names "gonadotrophin-releasing hormone (GnRH, gonadorelin) and its agonist analogues (e.g. buserelin, deslorelin, goserelin, histrelin, leuprorelin, nafarelin and triptorelin)" ¹⁰. Cetrorelix is an antagonist of GnRH, not an agonist analog, and it is not among those examples ¹, ¹⁰.

What JumpstartMD offers

JumpstartMD does not prescribe cetrorelix. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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Compounded medications are not FDA-approved, and FDA does not review their safety, effectiveness, or quality before they are marketed. A licensed clinician decides after an evaluation whether a peptide is appropriate for you, and not every patient will qualify.