What Is Synarel? Uses, Dosage, and What You Need to Know in 2026

If your doctor has prescribed Synarel or mentioned nafarelin as a treatment option, you probably have a lot of questions. What is it? How does it work? What should you expect? This guide covers everything you need to know about Synarel in plain language.

What Is Synarel?

Synarel is the brand name for nafarelin acetate, a prescription nasal spray medication. Nafarelin is a synthetic analog of gonadotropin-releasing hormone (GnRH) — a naturally occurring hormone that controls sex hormone production. Synarel is manufactured by Pfizer (G.D. Searle LLC) and was originally FDA-approved in February 1991.

Synarel belongs to a class of medications called GnRH agonists. These drugs work by overactivating — and then shutting down — the body's hormone production system. The end result is a significant reduction in estrogen (and testosterone), which is therapeutic for certain hormone-sensitive conditions.

What Is Synarel Used For?

Synarel has two FDA-approved indications:

Endometriosis (in women 18 and older): Synarel is used to relieve the pain associated with endometriosis and reduce the size of endometrial implants — tissue that grows outside the uterus.

Central Precocious Puberty (CPP) (in children age 2 and older): Synarel halts early pubertal development in children diagnosed with CPP — a condition where puberty begins abnormally early due to premature hormonal activation.

Synarel is also used off-label for:

IVF (in vitro fertilization): to prevent premature ovulation during controlled ovarian stimulation cycles

Uterine fibroids: to reduce fibroid size before surgery

Transgender hormone therapy: as a puberty blocker in transgender youth

Polycystic ovary syndrome (PCOS) and hirsutism

How Is Synarel Taken?

Synarel comes as a metered-dose nasal spray. Each actuation delivers 200 mcg of nafarelin base. Administration guidelines:

Endometriosis: 1 spray into one nostril in the morning, 1 spray into the other nostril in the evening (400 mcg/day total). Started on days 2–4 of the menstrual cycle. Treatment duration: up to 6 months.

CPP: 2 sprays into each nostril morning and evening (1,600 mcg/day). May be increased to 1,800 mcg/day (3 sprays into alternating nostrils three times daily) if needed.

Important usage tips:

Do not sneeze during or immediately after dosing — this can impair drug absorption

Wait at least 2 hours before using any other nasal spray (including decongestants)

Prime the pump before first use by spraying into the air until a fine mist appears

Clean the spray tip before and after each use

Store upright at room temperature (68°F–77°F), away from light

How Long Does a Bottle of Synarel Last?

Each bottle contains 8 mL (approximately 60 sprays):

At 400 mcg/day (endometriosis dose): approximately 30 days per bottle

At 1,600 mcg/day (CPP dose): approximately 7 days per bottle

How Much Does Synarel Cost?

Synarel is expensive — approximately $3,100–$3,500 per bottle at cash prices. There is no generic version of Synarel available in the United States as of 2026. With insurance and prior authorization, copays vary but can be significantly lower. Pfizer's patient assistance program may provide the medication at no cost for eligible uninsured or underinsured patients.

Is Synarel a Controlled Substance?

No. Synarel (nafarelin acetate) is not a DEA-controlled substance. It is a prescription-only medication, but it does not carry the scheduling restrictions that apply to controlled substances like opioids or stimulants. This means prescriptions can be refilled without the limitations imposed on Schedule II–V medications.

For a detailed review of what to expect from treatment, see our guide to Synarel side effects.

If you're having trouble finding Synarel in stock, medfinder can locate a pharmacy near you that has it available.