Nafarelin
Also known as Synarel
Nafarelin is a potent synthetic GnRH agonist formulated as an intranasal spray, distinguishing it from most other GnRH agonists that require injection. It is approved for management of endometriosis and central precocious puberty. As with other GnRH agonists, it produces an initial gonadotropin flare followed by sustained hypoestrogenic suppression with continued use. Treatment courses are typically time-limited due to bone density concerns with prolonged hypoestrogenism.
Reported benefits
- Reduces endometriosis-associated pelvic pain
- Suppresses premature pubertal development in central precocious puberty
- Non-injectable administration route
- Used as an adjunct in some fertility stimulation protocols
How it works
Nafarelin agonizes pituitary GnRH receptors; sustained daily exposure downregulates receptor sensitivity and reduces LH/FSH output, lowering circulating estrogen (or, in precocious puberty, slowing pubertal hormone progression). The intranasal route achieves systemic exposure despite modest and variable bioavailability compared with injectable agonists.
Dosing ranges
| Tier | Dose | Frequency |
|---|---|---|
| Low | 400 mcg | daily, divided into two intranasal doses |
| Moderate | 600 mcg | daily, divided doses |
| High | 800 mcg | daily, divided doses (upper labeled range) |
Estimate your dose
Dose estimator
Educational estimate for Nafarelin, scaled to body size. Not medical advice.
Read before using
This tool produces a rough, educational estimate by scaling commonly-published research ranges to lean body mass. It is not a prescription, medical advice, or a substitute for a licensed clinician. Most peptides use fixed dosing, not weight-based dosing. Individual needs vary. You are solely responsible for how you use this information.
Mixing & syringe units
Target dose follows the estimate above. Change it there, or edit it directly below.
Reconstitution calculator
How much water to add and how many insulin-syringe units to draw for Nafarelin. Educational only.
Draw to this mark
12units
= 0.12 mL for a 600 mcg dose
Concentration
5,000 mcg/mL
Doses per vial
16
A U-100 syringe reads 100 units per mL. This is a reconstitution math helper only, not a prescription or dosing advice. Verify every calculation and consult a qualified healthcare provider.
Possible side effects
Common protocols
Common questions
What is Nafarelin used for?
Nafarelin is a potent synthetic GnRH agonist formulated as an intranasal spray, distinguishing it from most other GnRH agonists that require injection. It is approved for management of endometriosis and central precocious puberty. As with other GnRH agonists, it produces an initial gonadotropin flare followed by sustained hypoestrogenic suppression with continued use. Treatment courses are typically time-limited due to bone density concerns with prolonged hypoestrogenism. Reported benefits include reduces endometriosis-associated pelvic pain, suppresses premature pubertal development in central precocious puberty, non-injectable administration route.
What is a typical Nafarelin dose?
Reported ranges run 400-800 mcg. A low protocol is 400 mcg daily, divided into two intranasal doses, and a high protocol is 800 mcg daily, divided doses (upper labeled range). This is reference information, not a dosing recommendation.
What is the half life of Nafarelin?
Approximately 3 hours. That is what sets the dosing frequency, and it is why the timing guidance is as directed by your clinician.
How is Nafarelin administered?
Nasal: nasal spray. Delivered as a metered intranasal spray; it is not injected.
How long is a Nafarelin cycle?
Typically up to 6 months per course for endometriosis on, followed by Per prescriber; extended or repeated courses require bone density monitoring off. Prolonged use is limited by hypoestrogenic effects on bone.
What are the side effects of Nafarelin?
Reported side effects include hot flashes, vaginal dryness, headache, nasal irritation, bone mineral density loss with extended courses. Evidence level for this compound is well studied.
Partner offer · $20 off
When did you last
check your blood work?
Regular blood work catches changes early. At-home collection with free pickup, 50+ biomarkers, and results in 72 hours.
- 1Order your kitTakes two minutes online, $20 off with this link.
- 2Collect at homePainless draw with free home pickup, no lab visit.
- 3Results in 72 hours50+ biomarkers with clear optimal ranges.
Partner offer · opens rythm.health
Educational use only, not medical advice. This profile is provided for research and educational purposes. Nafarelin may be a research compound or a prescription medication; nothing here is intended to diagnose, treat, cure, or prevent any disease. Dosing figures reflect commonly-published research ranges, not a prescription. Consult a qualified healthcare provider before making any health decision. Read the full disclaimer →