Buserelin
A synthetic GnRH agonist that suppresses hormones to help treat prostate cancer, endometriosis, and infertility
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Suggested dose
200 – 500 mcg
Compound profile
Scientific & efficacy data
Hormone Support
Peptide profile
Strong human trials
Buserelin
500 mcg · Once daily
Molecular formula
C60H86N16O13
- Mol. weight
- 1239.4 g/mol
- CAS number
- 57773-65-6
- PubChem
- 50225
- Developed · 1983
- Hoechst AG Research Team
Hoechst AG (now Sanofi)
Amino acid sequence
pGlu-His-Trp-Ser-Tyr-D-Ser-Leu-Arg-Pro-NHEtHormone Suppression
Reversible hormone suppression after treatment stops
Cancer Management
Suppresses testosterone to near-castrate levels for prostate cancer management
Fertility Support
Improves fertility outcomes when combined with IVF protocols
Dosing
How much do I take?
200 – 500 mcg · subcutaneous
200 – 500 mcg
Covers all 5 documented dose levels · 3 administration routes · timing · dose-adjustment guidance.
Suitability
Is this right for me?
Best for managing advanced prostate cancer & treating endometriosis and reducing associated pain
Best for
Managing advanced prostate cancer
Buserelin is particularly well-suited for individuals focused on managing advanced prostate cancer. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Treating endometriosis and reducing associated pain
Buserelin is particularly well-suited for individuals focused on treating endometriosis and reducing associated pain. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Optimizing ovarian response during fertility treatments
Buserelin is particularly well-suited for individuals focused on optimizing ovarian response during fertility treatments. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Consider alternatives if
Do not use if
Use with caution if
Not sure?
Compare Buserelin with similar peptides to find the best fit for your goals.
Administration
How do I use it?
Subcutaneous injection · Intranasal spray
Route
Subcutaneous injection (into the fatty tissue just under the skin)—allows for consistent absorption and can be self-administered at home after proper training
Best sites
Covers reconstitution · step-by-step technique · storage · a sample daily schedule.
Safety
Is it safe?
Buserelin is an FDA-approved GnRH agonist with safety data from Phase 3 trials and decades of clinical use, but carries well-documented risks from intentional testosterone/estrogen suppression.
The initial testosterone flare (first 2-3 weeks) can worsen prostate cancer symptoms and cause tumor flare pain in 10-20% of patients. Long-term use causes bone density loss of 2-3% annually, with vertebral fractures in 10-20% of long-term users.
Cardiovascular risks include increased MI and stroke in men over 65. Hot flashes affect 40-80%, erectile dysfunction is nearly universal, and liver enzyme elevations occur in 5%. Nasal spray formulation causes local irritation in 20-30% of users.
Buserelin was studied through Phase 3 clinical trials before FDA approval, with decades of post-market pharmacovigilance data. The flare phenomenon, bone loss, cardiovascular effects, and endocrine complications are well-characterized from long-term studies spanning over 30 years.
Comparative safety data with GnRH antagonists demonstrates buserelin's disadvantage regarding initial flare effect but similar long-term side effect profiles.
Stop and seek help if
- Severe or worsening side effects that don't improve with dose adjustment or supportive care
- Signs of an allergic reaction—rash, hives, swelling, or difficulty breathing
- Your healthcare provider recommends discontinuation based on your clinical response
- Development of any new medical condition that may be contraindicated with Buserelin
- Pregnancy or planning to become pregnant (unless specifically approved for use during pregnancy)
- Abnormal lab results or clinical markers that suggest adverse effects
Buserelin should only be started, adjusted, or discontinued under medical supervision. This information is for educational purposes only and does not replace professional medical advice. Never stop a prescribed treatment without consulting your healthcare provider first, as abrupt discontinuation may have consequences.
With other peptides
- Safe:Anti-androgens (like bicalutamide) for prostate cancer—provides additional tumor control — May be used together under medical guidance.
- Safe:Gonadotropins during IVF—enhances ovarian response and timing — May be used together under medical guidance.
- Safe:NSAIDs—helps manage pain and inflammation from endometriosis — May be used together under medical guidance.
With medications
- Caution:Other GnRH agonists—redundant and increases side effects — Use with caution—discuss with your healthcare provider.
- Caution:Alcohol in excess—may worsen hot flashes and mood changes — Use with caution—discuss with your healthcare provider.
With supplements
- Safe:Multivitamins — Generally safe to take alongside Buserelin. Space doses apart if taking oral formulations to ensure optimal absorption.
- Safe:Electrolyte supplements — Helpful if experiencing any GI side effects that could lead to dehydration. Safe to combine.
Effectiveness
How do I know it's working?
Strong human trials
Evidence level
Strong human trials
(Phase 3 or FDA approved)
Regulatory status
FDA approved for other use
Onset of effects
Moderate
(1-2 weeks)
How it works
Buserelin is a GnRH agonist that first stimulates hormone release, then shuts down the whole system.
For endometriosis, this lowers estrogen dramatically, reducing tissue growth and pain. Available as injections or nasal spray for flexibility.
The deeper mechanism
Buserelin is a nonapeptide GnRH agonist with D-serine substitution at position 6. Initial agonistic activity causes FSH/LH release (flare, 7-14 days), followed by receptor desensitization and downregulation, achieving 90%+ suppression of testosterone and estrogen within 3-4 weeks.
Signs it's working
Treatment Response
- Improvement in the primary symptoms or condition being treated
- Positive changes in relevant lab values or clinical markers
- Consistent, stable response to Buserelin over time
- Reduction in symptom frequency or severity
General Well-being
- Improved energy levels and daily functioning
- Better quality of life related to the treated condition
- Manageable or absent side effects indicating good tolerance
- Positive feedback from healthcare provider during check-ups
Not seeing results? Common reasons
- Not at therapeutic dose yet—initial doses are for building tolerance, not maximum effect
- Insufficient time at target dose—most compounds need several weeks to show full benefits
- Inconsistent dosing schedule—regular, consistent use is crucial for optimal results
- Individual variation in response—genetics, metabolism, and other factors affect outcomes
- Underlying conditions or medications interfering with absorption or effectiveness
- Improper storage leading to degraded product—always verify proper storage conditions
Key research
Clinical trials
Tested in people
31 registered studies, none currently enrolling.
By phase
A trial spanning two phases is counted in both, so these can sum above the total. Observational studies carry no phase.
What kind of research
About 14,723 people took part in the studies that actually administered Buserelin. Observational studies analyse the records of people already taking it — nobody was given anything for the study, so they are counted separately and cannot show cause and effect.
Most recent
UTN-01-2022
Friedrich-Schiller-Universitaet Jena
Effect of GnRH Agonist Treatment Protocols on Ovarian Reserve
Tanta University
Two Studies for Patients With Unfavorable Intermediate Risk Prostate Cancer Testing Less Intense Treatment for Patients With a Low Gene Risk Score and Testing a More Intense Treatment for Patients With a Higher Gene Risk Score, The Guidance Trial
NRG Oncology
Sources: ClinicalTrials.gov, the EU Clinical Trials Information System and ISRCTN, deduplicated so a study registered twice is counted once. A study is counted when Buserelin is named as an intervention; studies that only mention it in passing are not.
Questions
Frequently asked
How quickly does buserelin work?
You'll see some effects within 1-2 weeks, but full benefits take 4-6 weeks. For fertility, timing is precise—ovulation is prevented within days. For cancer, it takes several weeks to see tumor response.
Is buserelin reversible?
Yes! Once you stop taking it, your hormone levels return to normal within 4-8 weeks. Sexual function, mood, and energy improve as hormones bounce back.
Does buserelin hurt when injected?
Most people say the injection is a quick pinch, similar to other shots. Some experience minor bruising or redness at the injection site. Your doctor can show you proper injection technique to minimize discomfort.
Can I use buserelin if I want kids later?
For men with prostate cancer: fertility may be affected, but hormones usually recover after treatment stops. For women with endometriosis: buserelin actually improves fertility by reducing pain and improving egg quality during IVF. Talk to your doctor about your specific situation.
What about the nasal spray—does it work as well as injections?
Yes, the nasal spray works just as well if you use it correctly. You need to spray more frequently (usually 3 times per day), but hormone suppression is equally effective. Some people prefer it because there are no needles.
Will my hair fall out?
Hair loss is not a common side effect of buserelin. You might notice some thinning due to hormone suppression, but it's usually temporary and mild compared to chemotherapy.
How long can I take buserelin?
For endometriosis, doctors typically limit it to 6-12 months due to bone loss risk. For prostate cancer, you might take it indefinitely. For fertility, it's only a few weeks. Your doctor will determine what's safe for your situation.
Is buserelin available in the United States?
Not under the brand name Suprefact. However, similar GnRH agonists like leuprolide (Lupron) and goserelin (Zoladex) are available in the US and work similarly.
Further reading
History & related research
History · since 1982
The first GnRH agonist that taught doctors how to turn off hormone signals to fight cancer and help couples have babies
Buserelin is a man-made copy of a natural hormone that controls sex hormones in your body. It was one of the first drugs in its class, developed by Hoechst in the 1980s.
Read the full history of BuserelinReady for the protocol?
Every dosing tier, administration route, timing note, and dose-adjustment rule for Buserelin, on one page.