nafarelin (Rx)

Brand and Other Names:Synarel

Dosing & Uses


Dosage Forms & Strengths

nasal spray

  • 2mg/mL


1 spray (200 mcg/spray) in one nostril qAM, 1 spray in the other nostril qPM (total 400 mcg/day) on days 2-4 of menstrual cycle (2 sprays/day)

May increase to 800 mcg/day if still menstruating after 2 month: 1 spray in each nostril twice daily

Maximum treatment duration: 6 months

Dosage Forms & Strengths

nasal spray

  • 200mcg/spray

Central Precocious Puberty

<2 years: Safety and efficacy not established

≥2 years: 2 sprays (200 mcg/spray) in each nostril twice daily (total 1600 mcg/day)

May increase to 1800 mcg/day: 3 sprays (200 mcg/spray) into alternating nostrils TID (total 9 sprays/day)

Discontinue when puberty onset is desired


Adverse Effects


Acne (10%)

Breast enlargement (8%)

Vaginal bleeding (8%)

Seborrhea (3%)

Emotional lability (6%)

Vaginal discharge (3%)

Rhinitis (5%)

Body odor (4%)

Increase in pubic hair (5%)

Frequency Not Defined


Breast engorgement


Maculopapular rash




Eye pain

Postmarketing Reports

Liver injury

Pituitary apoplexy


Pituitary gland changes

Liver injury (rare)

Ovarian hyperstimulation syndrome

Psychiatric Disorders: Emotional lability, including crying, irritability, impatience, anger, and aggression; mood swings, depression, including rare reports of suicidal ideation and attempt, in children treated for central precocious puberty

Pseudotumor cerebri (idiopathic intracranial hypertension)




Pregnancy, hypersensitivity, lactation, undiagnosed abnormal vaginal bleeding


Goal in adult females is to suppress menstruation; max treatment period 6 mth

May cause increase in bone turnover & decrease in bone mineral content

Ovarian cysts may develop within first 2 months of therapy and occur more commonly in women with polycystic ovarian disease

Cases of pituitary apoplexy reported

Use caution in patients with risk factors for decreased bone mineral density

Irregular or incomplete daily doses may result in stimulation of the pituitary-gonadal axis; counsel caregivers to assure full compliance

During first month of treatment, may initially expect some signs of puberty, e.g., vaginal bleeding or breast enlargement, may occur; such changes should resolve soon after first month; if such resolution does not occur within first two months of treatment, this may be due to lack of compliance or presence of gonadotropin independent sexual precocity; if both possibilities excluded, the dose omay be increased to 1800 mcg/day administered as 600 mcg tid

Patients with intercurrent rhinitis should consult their physician for use of topical nasal decongestant; if use of topical nasal decongestant required during treatment decongestant should not be used until at least 2 hr after administering therapy; sneezing during or immediately after administering therapy should be avoided, if possible, since may impair drug absorption

Convulsions reported in patients receiving GnRH agonists; reports with GnRH agonists have included patients with a history of seizures, epilepsy, cerebrovascular disorders, central nervous system anomalies or tumors, and patients on concomitant medications that have been associated with convulsions such as bupropion and SSRIs; convulsions also reported in patients in the absence of any of the conditions listed

Psychiatric events reported in patients taking GnRH agonists; postmarketing reports with this class of drugs include symptoms of emotional lability, such as crying, irritability, impatience, anger, and aggression; monitor for development or worsening of psychiatric symptoms during treatment

Depression may occur or worsen during treatment with GnRH agonists; carefully observe women for depression, especially those with a history of depression, and consider whether risks of continuing therapy outweigh benefits; women with new or worsening depression should be referred to a mental health professional, as appropriate; inform patients that depression may occur or worsen during treatment with GnRH agonists, especially in patients with history of depression; advise patients to immediately report thoughts and behaviors of concern to healthcare providers

Pseudotumor cerebri (idiopathic intracranial hypertension) reported in pediatric patients receiving GnRH agonists, including leuprolide acetate; monitor patients for signs and symptoms of pseudotumor cerebri, including headache, papilledema, blurred vision, diplopia, loss of vision, pain behind the eye or pain with eye movement, tinnitus, dizziness, and nausea; inform patients and caregivers that reports of pseudotumor cerebri have occurred


Pregnancy & Lactation

Pregnancy Category: X

Lactation: Excretion in milk unknown, contraindicated

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.



Mechanism of Action

Synthetic decapeptide that is an agonist of LHRH, desensitizes response to endogenous GnRH, which in turn reduces secretion of LH and FSH and subsequently causes decreased ovarian and testicular production


Peak serum time: 10-45 min

Protein Bound: 78-84%

Metabolism: Degraded by peptidase

Metabolites: Dipeptide, tripeptide, pentapeptide, hexapeptide amide, D-naphthylalanine, 2-naphthylacetic acid (inactive)

Excretion: Urine (44-55%); feces (19-44%)

Half-Life: 3 hr

Bioavailability (1-6%)

Onset: 1 month (initial effect)

Peak effect: 12 wk (endometriosis); 4-8 hr (gonadotropin secretion stimulation)



Synarel nasal
2 mg/mL aerosol

Copyright © 2010 First DataBank, Inc.


Patient Handout

Patient Education
nafarelin nasal


(NAF-a-REL-in AS-e-tate)


USES: Nafarelin is used in women to treat a condition in which the tissue that normally lines the inside of the uterus grows in the wrong place (endometriosis). This medication helps to decrease the abnormal tissue and also the symptoms of endometriosis (such as pelvic pain, painful menstrual cramps, and pain during/after sex).This medication is also used by children to treat a certain type of early puberty (central precocious puberty, gonadotropin-dependent). It helps to slow the bone aging and height growth rate so that both are near normal, and it helps to stop or reverse signs of early puberty (such as breast growth in girls, growth of sexual organs in boys).Nafarelin is similar to a natural hormone made by the body (gonadotropin-releasing hormone-GnRH). It works by decreasing the testosterone hormones in boys and estrogen hormones in women and girls.

HOW TO USE: Read the Medication Guide and, if available, the Patient Information Leaflet provided by your pharmacist before you start using nafarelin and each time you get a refill. Follow the illustrated directions for the proper use of this medication. If you have any questions, ask your doctor or pharmacist.Follow the instructions for test sprays in the air if you are using a bottle for the first time. A fine mist is a sign that the spray is working properly.Gently blow your nose before using this drug. For very young children, it may be necessary to clear the nose with a bulb syringe.Use this medication as directed by your doctor, usually twice daily (about every 12 hours). If you are using more than 1 spray at a time, wait 30 seconds between each spray. Avoid spraying this medication in your eyes. Also, avoid sneezing during or right after using this medication because this may decrease the amount of medication absorbed. Follow the detailed instructions for cleaning the spray tip. It is important to clean the spray tip after each use.The dosage and length of treatment are based on your medical condition and response to treatment.It is very important to continue using this medication exactly as prescribed by your doctor. Do not skip any doses. To help you remember, use it at the same times each day.Ask your doctor or pharmacist to find out how long each bottle of the nasal spray should last. Do not use the nasal spray bottle longer, even if there is medication left over, because you will not get a full dose. Make sure to get your medication refills a few days early so that you will not run out of your medication.Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase.If you need to use a nasal decongestant spray while using this medication, wait at least 2 hours after using this medication before using the decongestant.When you first start this medication, worsening of symptoms may occur (such as increased vaginal bleeding for women treating endometriosis, or vaginal bleeding/period, increase in breast size/pubic hair, oily skin, or body odor for children treating early puberty). These symptoms should get better after the first month of treatment. Tell your doctor if your symptoms do not get better or if they get worse after 2 months of treatment.

SIDE EFFECTS: Nasal irritation, hot flashes, or vaginal discharge may occur in children. Nasal irritation, hot flashes, headaches, decreased sexual interest, muscle pain, vaginal dryness, acne, or decrease in breast size may occur in women. If any of these effects last or get worse, tell the doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell the doctor right away if any of these serious side effects occur: mental/mood changes (such as depression, thoughts of suicide, mood swings, aggression).For women using this medication, tell your doctor right away if you have any serious side effects, including: abdominal/lower back pain, bone pain, fast/pounding heartbeat, numbness/tingling of arms/legs, eye pain.Get medical help right away if any of these very serious side effects occur: seizures.Children using nafarelin may be at risk for increased pressure around the brain (intracranial hypertension). Get medical help right away if your child has any of these very serious side effects: nausea/vomiting that doesn't stop, headache that is severe or doesn't go away, eye pain, vision changes (such as blurred/double vision, decreased vision), ringing in the ears.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before using nafarelin, tell your doctor or pharmacist if you are allergic to it; or to GnRH or other GnRH-like hormones (such as leuprolide); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: unexplained abnormal vaginal bleeding, smoking, daily alcohol use, bone loss (osteoporosis) or family history of osteoporosis, polycystic ovarian disease, high cholesterol/triglyceride levels, seizures, mental/mood problems (such as depression).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This medication must not be used during pregnancy. It may harm an unborn baby. Women should start this medication between days 2 and 4 of their period. Although periods and the release of eggs (ovulation) may stop while you are using this drug, this is not a reliable form of birth control. Discuss the use of non-hormonal forms of birth control (such as condoms, diaphragm with spermicide) with your doctor. If you become pregnant or think you may be pregnant, tell your doctor right away.It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: See also How to Use section.Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.This medication may interfere with certain lab tests (such as tests for pituitary gonadotropic and gonadal functions), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

NOTES: Do not share this medication with others.Lab and/or medical tests (such as growth/bone age velocity in children) should be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

MISSED DOSE: If you miss a dose, use it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Use your next dose at the regular time. Do not double the dose to catch up.Vaginal bleeding may occur in girls/women who miss doses of this medication.

STORAGE: Store the bottle upright at room temperature away from light and moisture. Do not freeze. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

Information last revised May 2022. Copyright(c) 2023 First Databank, Inc.

IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.



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Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.