Nalmefene Side Effects

Some side effects of nalmefene may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to nalmefene: injectable solution

If you are addicted to narcotics or have been using an opioid medicine for a long time, you may have unpleasant withdrawal symptoms when you receive nalmefene to reverse the effects of a narcotic overdose.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Tell your caregivers right away if you have any of these symptoms, some of which may be signs that you need to receive additional doses of nalmefene:

• extreme drowsiness;

• weak or shallow breathing;

• chest pain or fluttering in your chest; or

• feeling like you might pass out.

Less serious side effects of nalmefene may include:

• nausea, vomiting, stomach pain;

• muscle or joint pain;

• chills; or

• feeling anxious or depressed.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.

For Healthcare Professionals

Applies to nalmefene: injectable solution

Gastrointestinal

Gastrointestinal side effects have occurred commonly, with nausea and vomiting observed in 18% and 9%, respectively, of treated patients. Diarrhea and dry mouth have been reported in less than 1% of patients.

Cardiovascular

Cardiovascular adverse effects including tachycardia, hypertension, hypotension, vasodilation, bradycardia, and arrhythmia have been reported in 5% or fewer of treated patients.

Nervous system

Nervous system side effects including postoperative pain, dizziness, headache, fever, and chills have been reported in less than 5% of treated patients. Somnolence, depression, agitation, nervousness, tremor, confusion, and myoclonus have been reported in less than 1% of patients.

Nalmefene administration may precipitate acute and extended withdrawal symptoms in opioid-dependent patients.

Respiratory

A 21-year-old male with no significant past medical history had decreased respirations following an exploratory laparotomy for presumed appendicitis. The patient developed acute pulmonary edema after receiving 75 mcg nalmefene in 25 mcg increments over 10 minutes. Clinical resolution of symptoms was prompt after supplemental oxygen and furosemide. It took 36 hours for the chest X-ray to improve.

Respiratory side effects have included pharyngitis (less than 1%). Pulmonary edema is an uncommon effect that has occurred with nalmefene administration.

Dermatologic

Dermatologic side effects have infrequently included pruritus (less than 1%).

Genitourinary

Genitourinary side effects have included rare reports of urinary retention (less than 1%).

Other

Other side effects including fever (3%) and chills (1%) have been reported.

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