Naloxone Side Effects

Medically reviewed by Philip Thornton, DipPharm. Last updated on Mar 1, 2024.

Applies to naloxone: injection solution.

Other dosage forms:

• nasal spray

Serious side effects of naloxone

Along with its needed effects, naloxone may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking naloxone:

For Healthcare Professionals

Applies to naloxone: compounding powder, injectable kit, injectable solution, nasal spray, oral solution.

General

This drug may precipitate abrupt opioid withdrawal in physically dependent persons; signs and symptoms may include body aches, fever, sweating, sneezing, yawning, nausea, vomiting, sweating, lacrimation, rhinorrhea, cramping, insomnia, chills/hot flashes, piloerection, tachycardia, anxiety, restlessness, irritability, tremulousness, hypertension, seizures, and cardiac arrest. In the neonate, opioid withdrawal may also include convulsions, excessive crying, and hyperactive reflexes.^[Ref]

Cardiovascular

• Common (1% to 10%): Tachycardia, hypotension, hypertension
• Uncommon (0.1% to 1%): Arrhythmia, bradycardia
• Rare (less than 0.1%): Fibrillation, cardiac arrest
• Frequency not reported: Left ventricular failure, flushing^[Ref]

In postoperative patients, many of whom had cardiovascular disease, the following cardiovascular side effects have been reported: hypotension, hypertension, atrial and ventricular tachycardia, ventricular fibrillation, left ventricular failure, and cardiac arrest. Death, coma, and encephalopathy have been reported as sequelae of these events.^[Ref]

Nervous system

• Common (1% to 10%): Dizziness, headache
• Uncommon (0.1% to 1%): Tremor
• Rare (less than 0.1%): Seizures
• Frequency not reported: Coma, encephalopathy, convulsions, paraesthesia, grand mal convulsion^[Ref]

Death, coma, and encephalopathy have been reported as a result of abrupt postoperative reversal of opioid depression, primarily in patients with preexisting cardiovascular disorders or in those who received other drugs with similar adverse cardiovascular effects.^[Ref]

Respiratory

• Very rare (less than 0.01%): Pulmonary edema
• Frequency not reported: Dyspnea, respiratory depression, hypoxia, nasal dryness, nasal edema, nasal congestion, nasal inflammation^[Ref]

It has been suggested that pulmonary edema may be due to a centrally mediated massive catecholamine response leading to a dramatic shift of blood volume into the pulmonary vascular bed resulting in increased hydrostatic pressures.

Nasal dryness, nasal edema, nasal congestion, and nasal inflammation were the most common adverse reactions reported in clinical trials with naloxone nasal spray.^[Ref]

Local

• Frequency not reported: Nonspecific injection site reactions, irritation of vessel was after IV administration^[Ref]

Gastrointestinal

• Common (1% to 10%): Nausea, vomiting
• Uncommon (0.1% to 1%): Diarrhea, dry mouth^[Ref]

Dermatologic

• Very rare (less than 0.01%): Erythema multiforme
• Frequency not reported: Sweating^[Ref]

Hypersensitivity

• Very rare (less than 0.01%): Allergic reactions including urticaria, rhinitis, dyspnea, Quincke's edema, anaphylactic shock^[Ref]

Psychiatric

• Frequency not reported: Agitation, hallucination, tremulousness^[Ref]

Musculoskeletal

• Frequency not reported: Musculoskeletal pain^[Ref]

Musculoskeletal pain was one of the more commonly reported adverse reactions in clinical trials with naloxone nasal spray.^[Ref]

Frequently asked questions

• How do I get free Narcan emergency kits?
• How long does Narcan (naloxone) block opiates?
• What are the different types of buprenorphine/naloxone?
• How do you administer Narcan (naloxone)?
• How does Narcan (naloxone) work in an overdose?
• Is this an addictive drug?
• What's the difference between naltrexone and naloxone?
• Will naloxone show up on a drug test?
• Does Sublocade have naloxone in it?

Further information

Naloxone side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

Medical Disclaimer