Narcan Side Effects Center

What Is Narcan?

Narcan (naloxone) is an opioid antagonist used for the complete or partial reversal of opioid overdose, including respiratory depression. Narcan is also used for diagnosis of suspected or known acute opioid overdose and also for blood pressure support in septic shock. Narcan is available in generic form.

What Are Side Effects of Narcan?

Narcan may cause serious side effects including:

• hives,
• difficulty breathing, and
• swelling of your face, lips, tongue or throat

Get medical help right away, if you have any of the symptoms listed above.

Common side effects of Narcan and narcotic drug withdrawal are:

• flushing,
• dizziness,
• tiredness,
• weakness,
• nervousness,
• restlessness,
• irritability,
• body aches,
• diarrhea,
• stomach pain,
• nausea,
• fever,
• chills,
• goosebumps,
• sneezing,
• shortness of breath, or
• runny nose.

Severe side effects of Narcan include:

• agitation,
• high or low blood pressure,
• cardiac arrhythmias,
• shortness of breath,
• pulmonary edema,
• abnormal brain function (encephalopathy),
• seizures,
• coma, and
• death.

Seek medical care or call 911 at once if you have the following serious side effects:

• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
• Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheadedness, or passing out;
• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Narcan?

Narcan is available as a sterile solution for intravenous, intramuscular, and subcutaneous administration in three strengths: 0.02, 0.4 and 1 mg of naloxone hydrochloride per mL in sterile solution; the 0.4 and 1 mg doses are also available in multidose vials. Use in neonates and other pediatric patients is based on weight (usually 0.01 mg per Kg) and may be adjusted; a pediatric consultant may help manages such patients. Opioid withdrawal syndrome may occur in some patients given large doses of Narcan.

Narcan During Pregnancy and Breastfeeding

Studies on the use of this drug in pregnant and women who are breastfeeding have not been done. Tell your doctor if you are pregnant or breastfeeding.

Additional Information

Our Narcan Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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

Because naloxone reverses opioid effects, this medicine may cause sudden withdrawal symptoms such as:

• nausea, vomiting, diarrhea, stomach pain;
• fever, sweating, body aches, weakness;
• tremors or shivering, fast heart rate, pounding heartbeats, increased blood pressure;
• goose bumps, shivering;
• runny nose, yawning; or
• feeling nervous, restless, or irritable.

Sudden withdrawal symptoms in a baby younger than 4 weeks old may be life-threatening if not treated the right way. Symptoms include crying, stiffness, overactive reflexes, and seizures. Call your doctor or get emergency medical help if you are not sure how to properly give this medicine to a baby.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.