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Synarel Side Effects

Generic Name: nafarelin

Note: This page contains side effects data for the generic drug nafarelin. It is possible that some of the dosage forms included below may not apply to the brand name Synarel.

For the Consumer

Applies to nafarelin: nasal spray

As well as its needed effects, nafarelin (the active ingredient contained in Synarel) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking nafarelin, check with your doctor immediately:

More common:For adults (female)
  • Breast enlargement
  • light vaginal bleeding between regular menstrual periods, called spotting
  • longer or heavier menstrual periods
  • vaginal bleeding between regular menstrual periods, called breakthrough bleeding
For children (male)
  • Body odor
  • growth of pubic hair
For children (female)
  • Body odor
  • breast enlargement
  • growth of pubic hair
  • light vaginal bleeding between regular menstrual periods, called spotting
  • longer or heavier menstrual periods
  • vaginal bleeding between regular menstrual periods, called breakthrough bleeding
Less common:
  • Chest pain
  • rash, hives or welts, itching
  • redness of the skin
Less common or rare:For adults (female)
  • Fast or irregular heartbeat
  • numbness or tingling of the hands or feet
  • pain in the eyes or joints
  • patchy brown or dark brown discoloration of the skin
  • pelvic bloating or tenderness
  • unexpected or excess milk flow from the breasts
  • unusual tiredness or weakness
Incidence not known:For adults (female)
  • Cough
  • difficulty with speaking
  • dizziness or lightheadedness
  • double vision
  • fainting
  • fast heartbeat
  • inability to move the arms, legs, or facial muscles
  • inability to speak
  • nausea
  • pain or discomfort in the arms, jaw, back, or neck
  • pain, redness, or swelling in the arm or leg
  • slow speech
  • sweating
  • troubled breathing
  • vomiting
  • yellow eyes or skin
Incidence not known
  • Anxiety or mental depression
  • changes in vision
  • cold, clammy, or pale skin
  • confusion
  • convulsions
  • headache
  • irregular heartbeats
  • nightmares or unusually vivid dreams
  • slow heart rate
  • vomiting
  • weakness

Minor Side Effects

Some nafarelin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:For adults (female)
  • Acne
  • dandruff
  • hot flashes
  • increase or decrease in sexual desire
  • increased hair growth, often abnormally distributed
  • mood swings
  • muscle pain
  • oily skin
  • pain during sexual intercourse
  • rapid weight gain
  • reduced breast size
  • stopping of menstrual periods
  • swelling of the feet or lower legs
  • vaginal dryness
For children (male)
  • Acne
  • dandruff
  • mood swings
  • oily skin
For children (female)
  • Acne
  • dandruff
  • hot flashes
  • mood swings
  • oily skin
Less common or rare:For adults (female)
  • Breast pain
  • headache (mild and transient)
  • irritated or runny nose
  • mental depression (mild and transient)
For children (male)
  • Irritated or runny nose
For children (female)
  • Irritated or runny nose
  • white or brownish vaginal discharge

For Healthcare Professionals

Applies to nafarelin: nasal spray


Hot flashes occurred commonly in adult women who were treated for endometriosis. Approximately 3% of children developed transient hot flashes.[Ref]

Very common (10% or more): Hot flashes/hot flush (up to 90%)
Common (1% to 10%): Chest pain, edema, hyper/hypotension
Frequency not reported: Palpitations
Postmarketing reports: Arterial thromboembolism, deep vein thrombosis, myocardial infarction, venous thromboembolism[Ref]


Very common (10% or more): Decreased libido (up to 23%), emotional/affect lability (up to 15%)
Common (1% to 10%): Depression, increased libido, insomnia
Postmarketing reports: Aggression, anger, impatience, irritability, suicidal ideation, suicide attempt[Ref]


Very common (10% or more): Vaginal dryness (up to 19%)
Common (1% to 10%): Transient breast enlargement, breast atrophy/decreased breast size, vulvovaginal dryness, artificial menopause, uterine hemorrhage, vaginal bleeding, white/brown vaginal discharge
Uncommon (0.1% to 1%): Ovarian cyst
Frequency not reported: Ovarian hyperstimulation syndrome[Ref]

Nervous system

Very common (10% or more): Headache (up to 18%)
Common (1% to 10%): Paresthesia
Frequency not reported: Migraines
Postmarketing reports: Convulsions, stroke, transient ischemic attack[Ref]


Very common (10% or more): Acne (up to 14%)
Common (1% to 10%): Transient increase in pubic hair, body odor, seborrhea, pruritus, rash, urticaria, hirsutism
Uncommon (0.1% to 1%): Alopecia[Ref]


Common (1% to 10%): Rhinitis, dyspnea, nasal irritation
Frequency not reported: Shortness of breath
Postmarketing reports: Interstitial pneumonitis, pulmonary embolism, pulmonary fibrosis[Ref]


Common (1% to 10%): Myalgia, decreased bone mineral density
Uncommon (0.1% to 1%): Arthralgia
Postmarketing reports: Arthritic symptoms[Ref]


Common (1% to 10%): Estrogen deficiency
Frequency not reported: Pituitary enlargement/asymmetry/pituitary gland changes (size and shape)
Postmarketing reports: Pituitary apoplexy[Ref]


Common (1% to 10%): Increased/decreased weight
Frequency not reported: Increased serum alkaline phosphatase, increased total cholesterol/triglycerides[Ref]


Common (1% to 10%): Drug hypersensitivity[Ref]


Frequency not reported: Adrenal rest tumor of the testis, pituitary gland adenoma[Ref]

A patient with congenital adrenal hyperplasia developed an adrenal rest tumor 8 months after discontinuing treatment; however, correlation to treatment is unlikely.

Pituitary gland adenomas have been observed in a few children receiving treatment; however, the relationship to treatment is unknown.[Ref]


Frequency not reported: Increased AST/ALT, serious liver injury[Ref]


Frequency not reported: Blurred vision[Ref]


Postmarketing reports: Crying


1. "Product Information. Synarel (nafarelin)." Roche Laboratories, Nutley, NJ.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Cerner Multum, Inc. "Australian Product Information." O 0

4. "Product Information. Synarel (nafarelin nasal)." Pfizer U.S. Pharmaceuticals Group, New York, NY.

5. "Product Information. Synarel Nasel Solution (nafarelin nasal)." Searle, Chicago, IL.

It is possible that some side effects of Synarel may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.