Multiple-dose protocol
Label- Dose
- 0.25 mg
- How often
- Once daily
- How long
- From stimulation day 5 or 6 until the hCG day; median 5 days
Premature LH surges in 1.0–1.9% in the phase 3 trials; clinical pregnancy 19.8–20.8% per attempt.
Approved drugGnRH antagonist
Cetrorelix
Cetrotide; SB-75, D-20761
- Common dose
- 0.25 mg daily during stimulation (about 5 days)
- Cycle
- One 1-week course
- Form
- Ready-made product
A ten-amino-acid analog of GnRH with five of its building blocks replaced, which turns it into a blocker. It occupies the pituitary’s GnRH receptor without switching it on, so LH falls within hours with no initial surge, holding off ovulation until a trigger shot is given.
Evidence. Approved in the EU (1999) and the US (2000) as Cetrotide, and as generic kits in the US since 2022, to stop premature ovulation during ovarian stimulation for IVF. In US phase 3 trials of 577 women, LH surges occurred in 0–1.9%. A long-acting form failed two phase 3 trials in enlarged prostate.
What it’s used for
Approved uses first, then uses tested in people, then claims that rest on animal studies or user reports.
- IVF and assisted reproduction
- LabelApproved to prevent premature LH surges (early ovulation) during ovarian stimulation. In US phase 3 trials of 577 women, surges occurred in 0–1.9%; clinical pregnancy rates were 19.8–22.6% per attempt.
- Ovarian hyperstimulation syndrome (OHSS)
- TrialAntagonist protocols (cetrorelix or ganirelix) cause less OHSS than long agonist protocols with similar live births: in a Cochrane review, OHSS risk fell from about 11% to 6–9%.
- Enlarged prostate (BPH)
- TrialNegative: a long-acting injection improved symptom scores in a phase 2 trial, but two 52-week placebo-controlled phase 3 trials in about 1,090 men found no difference. Never approved for this.
- Endometriosis
- TrialUnproven: in a pilot study of 15 women, 3 mg weekly for 8 weeks relieved symptoms in all and shrank disease in 9. No controlled trial followed.
- Uterine fibroids before surgery
- TrialUnproven: in 20 women given a depot form for 6–8 weeks before surgery, the largest fibroid shrank by about a third in the 16 who responded. Not approved for this.
Label: an approved use. Trial: tested in people, with the result.
Every compound’s uses, by body system: evidence map, and by condition: conditions A to Z.
Status
- Approval
- Approved in the US as Cetrotide 0.25 mg (EMD Serono, 2000) and as generic cetrorelix acetate kits (since 2022) to inhibit premature LH surges in women having controlled ovarian stimulation. The 3 mg single-dose kit is discontinued, and Teva is discontinuing its generic (FDA notice, November 2025).
- Approval history
- 1999EU (EMA): Cetrotide: preventing premature ovulation during ovarian stimulation for assisted reproduction
- 2000US FDA: Cetrotide 0.25 mg and 3 mg: inhibiting premature LH surges in IVF
- 2014Canada: Cetrotide 3 mg: cancelled after marketing
- 2022US FDA: Generic cetrorelix (Teva): first US generic kit approved
- 2025US FDA: Generic cetrorelix (Teva): being discontinued, per FDA shortage database notice
- European Union
- Prescription only. Cetrotide 0.25 mg has been centrally authorized since April 1999 to prevent premature ovulation during ovarian stimulation for assisted reproduction.
- United Kingdom
- Prescription-only medicine: Cetrotide 0.25 mg (Merck Serono, PLGB 11648/0263), to prevent premature ovulation during ovarian stimulation.
- Canada
- Prescription drug: Cetrotide 0.25 mg, marketed since March 2004; the 3 mg strength was cancelled in 2014.
- Australia
- Prescription only (Schedule 4). Cetrotide is registered; the TGA shortage database listed it in 2026, with supply reported available again from late August 2026.
- Sport (WADA 2026)
- Not banned in sportNot named on the 2026 list, and S0 doesn’t apply to an approved drug. S2.2.1 bans GnRH and its agonist analogues in males as testosterone-stimulating peptides; GnRH antagonists, which lower testosterone, aren’t named there or elsewhere.
Sport status follows the WADA Prohibited List in force since January 1, 2026; athletes should confirm with their anti-doping organization. Checked October 5, 2026. Status outside the US checked October 7, 2026 against EMA, MHRA, Health Canada and TGA records. By country: EU, UK, Canada, Australia. Status of every compound.
How it works
Cetrorelix blocks the GnRH receptor on the pituitary gland, the switch through which the brain hormone GnRH releases LH, the hormone whose mid-cycle surge sets off ovulation. By competing with natural GnRH, it lowers LH within about 1–2 hours, with no initial surge, so daily doses keep the LH surge from starting early during IVF stimulation. At the IVF dose FSH is little affected, and the effect reverses after stopping.
LabelBased on the product label.
Not known
Effects of repeated courses are little studied: the EU label notes limited experience with repeated stimulation cycles, and the US trials excluded women with polycystic ovary syndrome, low ovarian reserve or advanced endometriosis.
Protocol
Label
Cetrotide and generics
0.25 mg under the skin once a day, starting on day 5 (morning or evening) or day 6 (morning) of ovarian stimulation and continuing until the day of the hCG trigger.
Trial
Olivennes 2000; former Cetrotide 3 mg label
A single 3 mg dose in the late follicular phase, the former Cetrotide 3 mg regimen, prevented LH surges for at least 4 days; 0.25 mg daily followed if the trigger was later.
- Frequency
- Once daily
- Route
- Subcutaneous injection (lower belly)
- Timing
- About 24 hours apart, morning or evening, from stimulation day 5 or 6 through the day of the hCG trigger (label).
- Cycle
- One short course per IVF cycle: daily injections for a median of 5 days (range 1–15 in trials), stopped at the trigger. The EU label notes limited experience with repeated cycles.
One 1-week course, shown over 26 weeks
Common protocols
The ways Cetrorelix is most often run, each tagged with where it comes from.
Single-dose protocol (discontinued)
Label- Dose
- 3 mg once
- How often
- Single injection in the late follicular phase
- How long
- Covers at least 4 days; 0.25 mg daily after that if needed
The former Cetrotide 3 mg: no LH surge in 115 women in its phase 3 trial. No longer sold in the US, and cancelled in Canada in 2014.
Endometriosis (not approved)
Trial- Dose
- 3 mg
- How often
- Once weekly
- How long
- 8 weeks
Pilot study of 15 women: all reported a symptom-free period and disease regressed in 9. Estradiol hovered around 50 pg/mL. No controlled trial followed.
Enlarged prostate (not approved)
Trial- Dose
- Pamoate depot, 60 mg then 30 mg
- How often
- Two muscle injections 2 weeks apart
- How long
- Followed for 28 weeks
A phase 2 trial found a 4-point symptom gain over placebo, but two 52-week phase 3 trials of 78 mg doses found no difference from placebo.
Taking it
Where it goes
Under the skin of the lower belly, at least an inch from the navel, using a different spot each day (label). The EU label adds that injecting slowly can reduce site reactions.
If you miss a dose
The labels give no missed-dose rule; doses are meant to be about 24 hours apart. A gap can let LH surge early, so ask the fertility clinic how to proceed, and don’t double up.
What to expect
- 1–2 hours after a dose
LH suppression begins about 2 hours after 0.25 mg (1 hour after 3 mg), with no initial surge of LH or FSH.
Label - Days of stimulation
Daily doses hold off the LH surge until the trigger: premature surges in 0–1.9% of women across the phase 3 trials.
Label - After egg retrieval
Clinical pregnancy in 19.8–22.6% of women per attempt in the phase 3 trials. The effect on LH and FSH reverses after stopping.
Label
Side effects and what to do
Injection-site redness, swelling or itching (EU label: 9.4% with daily 0.25 mg)
Usually mild and brief. Rotating sites and injecting slowly help, the EU label says.
Ovarian hyperstimulation syndrome, moderate or severe (US label: 3.5%)
A risk of the stimulation itself. Belly swelling or pain, rapid weight gain or shortness of breath need prompt care.
Nausea 1.3% and headache 1.1% (US label, 949 women)
Usually mild.
Allergic reactions, including rare anaphylaxis
Can occur with the first dose; hives, face or throat swelling, or trouble breathing need emergency care.
Raised liver enzymes (US label: 1–2%, up to 3 times normal)
Seen on blood tests only; the label calls their significance unknown.
Stop and get medical help
Get emergency help for hives, face or throat swelling, or trouble breathing, especially after the first dose. Severe belly pain or swelling, rapid weight gain, shortness of breath or passing very little urine can mean severe OHSS.
By the numbers
From the trials in the Cetrotide label, in women having ovarian stimulation for IVF. There was no placebo group: the side-effect table counts everything reported from the first dose until pregnancy was confirmed, whatever the cause.
Side effects in the label’s trials
| Side effect | Cetrotiden=949 |
|---|---|
| Ovarian hyperstimulation syndrome, moderate or severe | 3.5 |
| Nausea | 1.3 |
| Headache | 1.1 |
Injection-site redness, bruising, itching and swelling were also reported, usually mild and brief; the label gives no rate.
- Liver enzymes (ALT, AST, GGT, alkaline phosphatase) rose in 1–2% of women, up to 3 times the upper limit of normal; the label calls the significance unknown.
- Across the five phase 2 and 3 trials, 732 women had 184 pregnancies, 21 of them after frozen-thawed embryo transfer.
- Two stillbirths were reported in the phase 3 studies.
Results
| Measure | Trial with a comparison drugn=159 | Single-group trialn=303 |
|---|---|---|
| Premature LH surge after starting | 1.9% | 1.0% |
| Got the hCG trigger shot | 96.2% | 96.0% |
| Had eggs collected | 94.3% | 93.1% |
| Clinical pregnancy, per woman | 20.8% | 19.8% |
| Clinical pregnancy, per embryo transfer | 24.1% | 23.3% |
An LH surge here means LH of 10 U/L or more with progesterone of 1 ng/mL or more.
How the body handles it
- Reaches the blood
- 85% of an injected dose
- Peak level
- About 1 to 2 hours after an injection
- Half-life
- 5.0 hours after one 0.25 mg dose, 20.6 hours with daily doses, 62.8 hours after a single 3 mg dose
- Spread in the body
- About 1 L per kg of body weight (volume of distribution)
- Bound to blood proteins
- 86%
- Cleared by
- Peptidases (protein-cutting enzymes); within 24 hours, 2–4% of a dose left unchanged in urine and 5–10% in bile
Source: Cetrotide prescribing information (revised 07/2025). Trials of different drugs enrolled different people, so compare across drugs with care.
Can it cause …?
The side effects people ask about most, answered one by one. Each answer says where it comes from.
- Headache
- LabelHeadache: 1.1% of 949 women in trials (US label); uncommon in the EU label.
- Nausea or vomiting
- LabelNausea: 1.3% of 949 women in trials (US label); uncommon in the EU label.
- Dizziness
- Not reportedNot listed in the labels. Low blood pressure was part of one severe allergic reaction, in a woman taking 10 mg a day for 7 months for another condition.
- Acne, rash or skin changes
- LabelInjection-site redness, swelling and itching: 9.4% with daily 0.25 mg (EU label). A rash can be part of an allergic reaction.
- Water retention or swelling
- LabelSwelling at the injection site is common. Belly swelling with rapid weight gain can signal OHSS, moderate or severe in 3.5% of women in trials.
- Anxiety, low mood or irritability
- Not reportedNot listed in the US or EU labels, whose trials gave it to 949 women for a few days per IVF cycle; the mood warnings of GnRH agonists don’t appear.
- Fast heartbeat or blood pressure changes
- Not reportedNot listed in the labels. Low blood pressure occurred as part of a rare severe allergic reaction.
- Liver strain
- LabelLiver enzymes (ALT, AST, GGT, alkaline phosphatase) rose to up to 3 times normal in 1–2% of women; the US label calls their significance unknown.
- Kidney problems
- LabelNo kidney harm is listed, but both labels rule it out with severe kidney impairment, and milder impairment hasn’t been studied.
- Cancer risk
- LabelLong-term animal cancer studies weren’t done. Gene-damage tests were negative apart from one hamster cell line; IVF exposure lasts only days per cycle.
- TirednessDiarrhea or constipationTrouble sleepingHair lossJoint or muscle painLow or high blood sugarMore hunger
- Not reportedNot listed in the US or EU labels, whose trials gave it to 949 women for a few days per IVF cycle.
Label: from the prescribing information. Not reported: studied in people and not reported. A side effect that hasn’t been reported can still happen, especially with long or high-dose use. Any of these across every compound: the side-effect finder.
Who should avoid it
What its label rules out or warns about, most important first.
- Allergy to cetrorelix, GnRH drugs or mannitol
- LabelRuled out by the labels, which also list extrinsic peptide hormones. Anaphylaxis has occurred with the first dose; the EU label advises against use with severe allergic conditions.
- Pregnancy or breastfeeding
- LabelRuled out. Pregnancy must be excluded before starting; in rats and rabbits it caused early pregnancy loss. Whether it passes into milk isn’t known.
- Severe kidney impairment
- LabelRuled out by both labels. Milder kidney impairment and liver impairment haven’t been studied, and the EU label urges caution in both.
- Polycystic ovaries or low ovarian reserve
- LabelExcluded from the US trials, so the label’s results don’t cover these women.
- Repeated stimulation cycles
- LabelThe EU label notes limited experience and advises use in repeat cycles only after a careful weighing of benefits and risks.
- Anyone 65 or older
- LabelThe US label says it isn’t intended for them; trial patients were 19–40.
Interactions
Only interactions stated on a product label or measured in a human study are listed.
- Gonadotropins used for stimulation (FSH, hMG)
- LabelAlways given together in IVF. No formal interaction studies exist, and the EU label says an interaction with gonadotropins can’t be fully excluded.
- Drugs that can release histamine in susceptible people
- LabelThe EU label says an interaction can’t be fully excluded, given cetrorelix’s potential for allergic-type reactions.
- Drugs cleared by liver CYP450 enzymes or by conjugation
- LabelLab studies suggest interactions are unlikely, the EU label says; no formal interaction studies were done.
Label: a product label rules it out, warns about it or lists the interaction. This isn’t a complete list: a pharmacist or doctor can check a specific medicine or condition. Every documented interaction, by medicine: drug interactions.
Special situations
What the label and studies say about pregnancy, breastfeeding, kidney and liver problems, age and surgery.
- Pregnancy
- LabelRuled out: pregnancy must be excluded before starting. In rats and rabbits it caused early pregnancy loss; animals that stayed pregnant had no more malformations.
- Breastfeeding
- LabelRuled out by both labels; whether it passes into breast milk isn’t known.
- Kidney problems
- LabelRuled out with severe kidney impairment. Milder impairment hasn’t been studied, and the EU label urges caution; 2–4% of a dose leaves unchanged in urine.
- Liver problems
- LabelNot studied in liver impairment; the EU label urges caution.
- Older adults
- LabelThe US label says it isn’t intended for anyone 65 or older; trial patients were 19–40.
- Children and teens
- LabelNot studied under 18; the EU label says there is no relevant use in children.
- Surgery and anesthesia
- PrecautionNo label advice. Egg retrieval is usually done under sedation; tell the team about all fertility drugs. Its effect on LH reverses within days of the last dose.
Label: what the prescribing information says. Precaution: not studied, so the caution follows from how it works or from a related drug. Ages are given as approved or studied; this site never gives doses for children. Across every compound: pregnancy, breastfeeding, kidney disease, liver disease, older adults and surgery.
Tracking and pairing
Worth tracking
- Follicle growth on ultrasound and estradiol (routine IVF monitoring)
- LH and progesterone if an early surge is suspected
- Signs of OHSS: belly swelling or pain, weight gain, breathlessness
- Allergic symptoms after the first dose
Often paired with
- hCG
Standard pairing: daily cetrorelix holds off ovulation until a single hCG injection triggers final egg maturation (label).
- Leuprolide
Because an antagonist doesn’t shut the pituitary down, a GnRH agonist such as leuprolide can trigger egg maturation instead of hCG, cutting OHSS risk; live births were lower in fresh-embryo cycles (Cochrane review).
Human studies
5 key published human studies, with how many people took part. Animal studies aren’t listed here.
-
Live birth was similar (OR 1.02; 12 trials, 2,303 women), and OHSS was less common with antagonists (OR 0.61; 36 trials, 7,944 women).
- Design
- Cochrane systematic review of randomized trials comparing GnRH antagonists (cetrorelix or ganirelix) with long GnRH agonist protocols in IVF
- Dose
- Antagonist vs long-course agonist protocols
- Length
- One stimulation cycle per trial (73 trials)
Al-Inany et al., Cochrane Database Syst Rev 2016, PMID 27126581
-
An LH and progesterone rise occurred in 3 of 188 women (1.6%) on cetrorelix; stimulation was shorter with fewer hMG ampoules, and fertilization and pregnancy rates were similar.
- Design
- Randomized phase III trial vs the GnRH agonist buserelin in IVF and ICSI cycles
- Dose
- 0.25 mg daily (188 women) vs buserelin (85)
- Length
- One stimulation cycle
Albano et al., Hum Reprod 2000, PMID 10686191
-
No LH surge occurred after cetrorelix; it gave fewer eggs and embryos but similar pregnancy rates, with shorter stimulation and less OHSS.
- Design
- Randomized controlled trial vs a triptorelin depot (long protocol) in IVF
- Dose
- Single 3 mg dose (115 women) vs triptorelin depot (39)
- Length
- One stimulation cycle
Olivennes et al., Fertil Steril 2000, PMID 10685535
-
Premature luteinization in 0.9%; ongoing clinical pregnancy 24% per transfer; severe OHSS 0.6%.
- Design
- Uncontrolled phase III study of the multiple-dose protocol
- Dose
- 0.25 mg daily for a mean 5.7 days
- Length
- One stimulation cycle
Felberbaum et al., Hum Reprod 2000, PMID 10783344
-
Symptom scores fell 4.0 and 3.7 points vs 3.8 on placebo, no difference.
- Design
- Randomized double-blind placebo-controlled phase 3 trial in benign prostatic hyperplasia, stopped after missing its primary endpoint
- Dose
- Cetrorelix pamoate 78 mg, then 78 or 52 mg, into muscle
- Length
- 52 weeks
AEterna Zentaris, results posted on ClinicalTrials.gov, NCT00449150
Trials under way
Registered trials that are still running, or that finished without published results, most important first. Checked on ClinicalTrials.gov, October 7, 2026.
Generic vs original cetrorelix 0.25 mg daily in 1,338 women having IVF or ICSI: cumulative live births (non-inferiority)
Recruiting; completion was expected December 2025, no results posted
Progesterone injected under the skin vs cetrorelix to suppress the LH surge in 230 women having freeze-all IVF cycles
Not yet recruiting (start planned January 2026); completion expected February 2027
Oral linzagolix vs injectable antagonists (ganirelix or cetrorelix) in 120 women having IVF: mature eggs retrieved
Not yet recruiting; start planned September 2026, completion expected December 2026
Half-dose (0.125 mg) vs standard 0.25 mg daily cetrorelix in 160 women with a BMI of 25 or more having ICSI: clinical pregnancy
Not yet recruiting; start planned September 2026, completion expected March 2028
Every compound’s registered trials: trials under way.
Limits of the evidence
Approval rests on five trials in 732 women aged 19–40 having IVF, which excluded polycystic ovary syndrome, low ovarian reserve and advanced endometriosis; each course lasts days. Follow-up of 316 newborns is the only offspring data. Data on repeated cycles are limited, and uses outside IVF, such as endometriosis, fibroids or enlarged prostate, rest on small pilot studies or phase 3 trials that failed.
How it’s supplied
Kits with one 0.25 mg powder vial and a prefilled syringe of 1 mL sterile water (Cetrotide and generics); the 3 mg single-dose kit is discontinued. Mixed and injected under the skin of the lower belly once a day, usually by the patient after training; the EU label wants the first dose given under medical supervision. It’s used as supplied, so the calculator and dose log don’t apply.
Not a research powder: each kit holds one 0.25 mg vial and a prefilled syringe of 1 mL water. The whole vial is dissolved, drawn up and injected at once, giving 0.25 mg in 1 mL; the EU label notes only about 0.21 mg is actually delivered.
Datasheet
- Half-life
- about 20–30 hours with daily dosing LabelUnder the skin in healthy women: 20.6 hours with 0.25 mg daily for 14 days, but 5.0 hours after a single 0.25 mg dose and 62.8 hours after a single 3 mg dose (US label). The EU label gives about 30 hours under the skin and 12 hours IV.
- Type
- Peptide, 10 amino acids
- Molecular weight
- 1,431.1 g/mol
- Formula
- C70H92ClN17O14
- Sequence
- (Ac-D-Nal)-(D-Cpa)-(D-Pal)-SY-(D-Cit)-LRP-(D-Ala)-NH2Nal = 3-(2-naphthyl)alanine, Cpa = 4-chlorophenylalanine, Pal = 3-(3-pyridyl)alanine, Cit = citrulline
- Storage before use
- Refrigerated at 2–8 °C in the carton, protected from light (US label). The EU label allows the unopened kit up to 3 months at room temperature, not above 30 °C; don’t freeze.
- After mixing or opening
- Mix just before use and inject at once; nothing is kept. Let the kit reach room temperature for about 30 minutes first (EU label).
- Half-life: Cetrotide prescribing information, Table 1 (DailyMed, September 2025); Cetrotide EU summary of product characteristics, section 5.2
- Molecule: Cetrotide label (sequence; 1,431.06 as anhydrous free base); PubChem CID 25074887; FDA GSRS UNII OON1HFZ4BA. Products contain the acetate.
- Storage: Label Cetrotide prescribing information, How Supplied (DailyMed, September 2025); Cetrotide EU summary of product characteristics, sections 6.3 and 6.4
Every compound side by side: the half-life chart and the storage chart.
Identifiers
- PubChem CID
- 25074887
- DrugBank
- DB00050
- ATC code
- H01CC02
- CAS number
- 120287-85-6 (cetrorelix); 130143-01-0 (acetate)
- UNII (FDA)
- OON1HFZ4BA (cetrorelix); W9Y8L7GP4C (acetate)
- Development codes
- SB-75 (Schally lab), D-20761 (ASTA Medica); D-20762 and AEZS-102 (pamoate depot, not approved)
- Brand names
- Cetrotide; generic cetrorelix acetate kits (US)
- First described
- Developed as SB-75 in Andrew Schally’s lab (Bajusz et al., 1988); first approved as Cetrotide, EU, 1999.
Every compound’s numbers: the identifiers table.
Product form and quality
Kits hold 0.26–0.27 mg of cetrorelix acetate, equal to 0.25 mg of cetrorelix; the EU label says about 0.21 mg is delivered after mixing losses. A slow-release pamoate salt was used only in trials.
Cautions
- Label: serious allergic reactions, including anaphylaxis with the first dose. The EU label asks for the first injection under medical supervision, with 30 minutes’ observation.
- Ruled out in pregnancy and breastfeeding and with severe kidney impairment (label).
- Ovarian hyperstimulation syndrome (OHSS) is a risk of the stimulation itself: moderate or severe in 3.5% of women in trials (US label).
- Injection-site redness, swelling and itching are common (9.4% in EU trials) and usually brief.
- Liver enzymes rose to up to 3 times normal in 1–2% of women; the label calls the significance unknown.
Questions
What is cetrorelix?
A ten-amino-acid analog of GnRH with five of its building blocks replaced, which turns it into a blocker. It occupies the pituitary’s GnRH receptor without switching it on, so LH falls within hours with no initial surge, holding off ovulation until a trigger shot is given.
How does cetrorelix work?
Cetrorelix blocks the GnRH receptor on the pituitary gland, the switch through which the brain hormone GnRH releases LH, the hormone whose mid-cycle surge sets off ovulation. By competing with natural GnRH, it lowers LH within about 1–2 hours, with no initial surge, so daily doses keep the LH surge from starting early during IVF stimulation. At the IVF dose FSH is little affected, and the effect reverses after stopping. Effects of repeated courses are little studied: the EU label notes limited experience with repeated stimulation cycles, and the US trials excluded women with polycystic ovary syndrome, low ovarian reserve or advanced endometriosis.
Is cetrorelix FDA-approved?
Approved in the US as Cetrotide 0.25 mg (EMD Serono, 2000) and as generic cetrorelix acetate kits (since 2022) to inhibit premature LH surges in women having controlled ovarian stimulation. The 3 mg single-dose kit is discontinued, and Teva is discontinuing its generic (FDA notice, November 2025).
What is the usual cetrorelix dose?
From the label (Cetrotide and generics): 0.25 mg under the skin once a day, starting on day 5 (morning or evening) or day 6 (morning) of ovarian stimulation and continuing until the day of the hCG trigger. From human studies (Olivennes 2000; former Cetrotide 3 mg): A single 3 mg dose in the late follicular phase, the former Cetrotide 3 mg regimen, prevented LH surges for at least 4 days; 0.25 mg daily followed if the trigger was later. These are the amounts sources reference, not recommendations.
How is cetrorelix given?
Mixed and injected under the skin of the lower belly once a day, usually by the patient after training; the EU label wants the first dose given under medical supervision. About 24 hours apart, morning or evening, from stimulation day 5 or 6 through the day of the hCG trigger (label).
Who should avoid cetrorelix?
Allergy to cetrorelix, GnRH drugs or mannitol: Ruled out by the labels, which also list extrinsic peptide hormones. Anaphylaxis has occurred with the first dose; the EU label advises against use with severe allergic conditions. Pregnancy or breastfeeding: Ruled out. Pregnancy must be excluded before starting; in rats and rabbits it caused early pregnancy loss. Whether it passes into milk isn’t known. Severe kidney impairment: Ruled out by both labels. Milder kidney impairment and liver impairment haven’t been studied, and the EU label urges caution in both. The “Who should avoid it” section lists 3 more groups and 3 interactions.
What is the half-life of cetrorelix?
About 20–30 hours with daily dosing, according to the prescribing information. Under the skin in healthy women: 20.6 hours with 0.25 mg daily for 14 days, but 5.0 hours after a single 0.25 mg dose and 62.8 hours after a single 3 mg dose (US label). The EU label gives about 30 hours under the skin and 12 hours IV.
How should cetrorelix be stored?
Before mixing: Refrigerated at 2–8 °C in the carton, protected from light (US label). The EU label allows the unopened kit up to 3 months at room temperature, not above 30 °C; don’t freeze. Mix just before use and inject at once; nothing is kept. Let the kit reach room temperature for about 30 minutes first (EU label).
Is cetrorelix banned in sport?
No. Not named on the 2026 list, and S0 doesn’t apply to an approved drug. S2.2.1 bans GnRH and its agonist analogues in males as testosterone-stimulating peptides; GnRH antagonists, which lower testosterone, aren’t named there or elsewhere.
Has cetrorelix been studied in people?
Yes. The human studies section lists 5 published studies. The largest, from 2016, included 12,212 people. Live birth was similar (OR 1.02; 12 trials, 2,303 women), and OHSS was less common with antagonists (OR 0.61; 36 trials, 7,944 women).
How long has cetrorelix been studied in people?
Trial IVF use lasts about 5 days per cycle. Prostate trials gave a depot form over 52 weeks, and one patient took 10 mg daily for 7 months (US label).
Does cetrorelix come in other forms, like a pill or nasal spray?
Label Injected under the skin only. The 3 mg single-dose form is discontinued, and a long-acting pamoate depot tested by injection into muscle was never approved. Oral GnRH blockers are different drugs.
Can you drink alcohol while taking cetrorelix?
No study No data; the labels don’t mention alcohol.
Can cetrorelix be taken with semaglutide or tirzepatide?
Label No study has combined them, and neither label lists an interaction. Semaglutide’s labels advise stopping it at least 2 months before a planned pregnancy, which affects timing around IVF.
What happens if you take too much cetrorelix?
Label No overdoses reported; single doses up to 120 mg were tolerated in other conditions (US label), and the EU label says overdose may prolong its effect. Call Poison Help (1-800-222-1222), or emergency services for severe symptoms.
Sources
- Cetrotide (cetrorelix acetate for injection) prescribing information (EMD Serono, July 2025; DailyMed, September 22, 2025)
- Cetrotide 0.25 mg EU summary of product characteristics (EMA product information, checked October 2026)
- Drugs@FDA: Cetrotide (NDA 021197, August 11, 2000); generic cetrorelix acetate kits (ANDA 215737, Teva, August 12, 2022; later Livzon, Qilu, Gland, Xiromed and Epic Pharma)
- FDA drug shortage database (openFDA): Teva cetrorelix acetate injection kit, “To Be Discontinued”, posted November 13, 2025
- Albano et al., cetrorelix vs buserelin, European phase III trial (Hum Reprod 2000) PMID 10686191
- Olivennes et al., single 3 mg cetrorelix vs triptorelin depot (Fertil Steril 2000) PMID 10685535
For the protocol details
- Cetrotide prescribing information, clinical pharmacology, clinical studies, precautions and dosage sections (DailyMed, September 2025)
- Cetrotide EU summary of product characteristics, sections 4.2, 4.4, 4.8 and 6.4 (EMA)
- Felberbaum et al., uncontrolled phase III study of cetrorelix 0.25 mg daily (Hum Reprod 2000) PMID 10783344
- Küpker et al., GnRH antagonist cetrorelix in endometriosis (Reprod Biomed Online 2002) PMID 12470539
- Debruyne et al., dose-ranging trial of cetrorelix pamoate in benign prostatic hyperplasia (Urology 2010) PMID 20932411
- ClinicalTrials.gov posted results for the phase 3 cetrorelix pamoate trials in BPH NCT00449150
- Youssef et al., GnRH agonist vs hCG for egg-maturation triggering, Cochrane review (Cochrane Database Syst Rev 2014) PMID 25358904
For how it works, who should avoid it and the limits of the evidence
- Cetrotide prescribing information, clinical pharmacology, clinical studies, contraindications, precautions and adverse reactions (EMD Serono, DailyMed, September 2025)
- Cetrotide EU summary of product characteristics, sections 4.3–4.6, 5.1 and 5.2 (EMA)
- Al-Inany et al., GnRH antagonists vs long agonist protocols in assisted reproduction, Cochrane review (Cochrane Database Syst Rev 2016) PMID 27126581
For uses, the side-effect questions, special situations, trials, identifiers and status outside the US
- Cetrotide prescribing information, all sections (EMD Serono, July 2025; DailyMed, September 22, 2025)
- Cetrotide 0.25 mg EU summary of product characteristics, sections 4.2–4.9, 5.1 and 5.2 (EMA)
- Cetrotide 0.25 mg UK summary of product characteristics (Merck Serono, PLGB 11648/0263, revised December 2024)
- Phase 3 cetrorelix pamoate trial in BPH, results posted on ClinicalTrials.gov (AEterna Zentaris) NCT00663858
- Felberbaum et al., depot cetrorelix before fibroid surgery (Hum Reprod 1998) PMID 9688409
- Bajusz et al., LH-RH antagonists with D-citrulline at position 6 (Proc Natl Acad Sci U S A 1988) PMID 3278323
- Reissmann et al., pharmacology of cetrorelix (D-20761) and its pamoate (D-20762) (Eur J Cancer 1996) PMID 8911120
- Semaglutide (Wegovy and Ozempic) prescribing information, section 8.1 (DailyMed, 2026)
- FDA Global Substance Registration System records for cetrorelix and cetrorelix acetate; PubChem; WHO ATC index
- EMA medicines data and French public medicines database: Cetrotide, central authorization April 1999 (checked October 8, 2026)
- Health Canada Drug Product Database entries for Cetrotide 0.25 mg and 3 mg (checked October 8, 2026)
- TGA product information and medicine shortage database entry for Cetrotide (AUST R 74888); Poisons Standard, October 2026 (cetrorelix in Schedule 4)
- ClinicalTrials.gov registry entries for the trials listed (checked October 8, 2026)