Short answer: In 794 women in the ganirelix clinical studies, adverse events at 1% or more were gynecological abdominal pain (4.8%), fetal death (3.7%), headache (3.0%), ovarian hyperstimulation syndrome (2.4%), vaginal bleeding (1.8%), injection site reaction (1.1%), nausea (1.1%) and stomach pain (1.0%), counted without regard to cause. There was no placebo group. Ganirelix has no boxed warning; allergic reactions are the main precaution.
What Ganirelix is approved for: Ganirelix Acetate Injection is a GnRH antagonist approved to prevent premature LH surges (early ovulation) in women having controlled ovarian hyperstimulation (Indications and Usage). It is used alongside FSH during an IVF or ICSI stimulation cycle. This page uses Organon's label; other makers' generic ganirelix labels are separate.
Source
Ganirelix Acetate Injection 250 mcg/0.5 mL, for subcutaneous use, prescribing information. Organon. DailyMed, version published October 12, 2026. DailyMed setid 32fb74ff-993a-49fe-8943-e029372b863e
No. The current Ganirelix label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Ganirelix.
| Adverse event | Ganirelix Acetate N=794, % (n) |
|---|---|
| Abdominal Pain (gynecological) | 4.8 (38) |
| Death Fetal | 3.7 (29) |
| Headache | 3.0 (24) |
| Ovarian Hyperstimulation Syndrome | 2.4 (19) |
| Vaginal Bleeding | 1.8 (14) |
| Injection Site Reaction | 1.1 (9) |
| Nausea | 1.1 (9) |
| Abdominal Pain (gastrointestinal) | 1.0 (8) |
Two randomized controlled studies; ganirelix was given for 1 to 14 days. Events were counted from the first ganirelix dose until pregnancy was confirmed by ultrasound, without regard to cause, so "death fetal" (pregnancy loss) is included. The comparison arms were other ganirelix doses or a GnRH agonist, not placebo.
A neutrophil count of 8.3 x 10^9/L or higher was seen in 11.9% of women in the controlled trials (up to 16.8 x 10^9/L). Downward shifts in hematocrit and total bilirubin were also seen. Their clinical significance was not determined.
After approval, rare allergic reactions including anaphylaxis (including anaphylactic shock), angioedema and hives have been reported, as early as the first dose.
An observational study of more than 1000 newborns found congenital anomalies after ganirelix cycles at a rate comparable with GnRH agonist cycles. The causal link between anomalies and ganirelix is unknown.
In 463 women on 250 mcg, a premature LH surge before hCG occurred in less than 1%. Mean ganirelix treatment was 5.4 days (2-14), and the ongoing pregnancy rate was 20.3% per attempt and 23.3% per transfer.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Who should not use it. Women with a known allergy to ganirelix or its ingredients, or to GnRH or any GnRH analog, and women who are or may be pregnant.
Specialist use and pregnancy. Ganirelix is prescribed by physicians experienced in infertility treatment, and pregnancy must be excluded before starting. In animal studies it increased litter loss, which could mean pregnancy loss in humans.
Allergic reactions. Allergic reactions, generalized and local, including anaphylactic shock, angioedema and hives, have been reported as early as the first dose. If one is suspected, ganirelix is stopped and treated. It is not advised in women with severe allergic conditions, and special care is taken with active allergies.
Ovarian hyperstimulation. hCG is withheld if the ovaries are abnormally enlarged on the last day of FSH, to reduce the chance of OHSS.
Blood test changes. High neutrophil counts were seen in 11.9% of women, along with lower hematocrit and bilirubin; the clinical significance was not determined.
Breastfeeding and older adults. Ganirelix should not be used while breastfeeding. Studies did not include enough people aged 65 and over.
From the Precautions and Dosage and Administration; the SPL has no separate patient leaflet that comes with Ganirelix:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.