Narcan dosage, forms, and strengths

Narcan (naloxone hydrochloride) is used as a quick-acting reversal agent in the setting of an opioid overdose. It can also be used off-label for opioid use disorder as part of a preventative management regimen, for opioid-induced pruritus (severe itching), and in the setting of a naloxone challenge (to assess for dependence and withdrawal syndrome). Narcan is administered as an injection or as a nasal spray and may be administered by family members, other caregivers, or healthcare professionals.

Narcan forms and strengths

Narcan is available in generic formulations as an injection, or as brand-name Narcan nasal spray. The dose of Narcan differs based on the route of administration.

• Injection: 0.4 mg/mL as a 1 mL or 10 mL vial; 1 mg/mL as a 2 mL vial

  • The injection can be administered intravenously (into a vein), intramuscularly (into the muscle), and subcutaneously (under the skin). In emergency situations and dependent upon availability, the injection formulation can be administered intranasally (nasal administration), intraosseous (into bone), or even through an endotracheal tube.

• Nasal spray: 4 mg per actuation

RELATED: Which naloxone formulation should you get?

Narcan dosage for adults

Narcan is an opioid antagonist, which means that it binds to opioid receptors to both reverse and block the effects of opioid receptor agonists (opioids or opiates). The term “opioids” is used interchangeably to include prescription medications, like morphine and oxycodone, and can include illicit opiates like heroin. If a patient is showing signs of an opioid overdose, Narcan can rapidly reverse the central nervous system (CNS) effects of the opioid. 

Even though Narcan can reverse the effects of an opioid, it only serves as a temporary measure in the setting of an overdose. Further medical care must be sought out as soon as possible after receiving and/or administering Narcan. 

It is also important to note than an opioid overdose can happen even when a person does not intentionally misuse an opioid prescribed legally by a healthcare provider. 

Narcan is not effective in treating overdoses of other medications like benzodiazepines, or drugs like cocaine.

Narcan can also be used in what is known as a Narcan challenge to determine withdrawal syndrome, to reverse slowed breathing observed with therapeutic opioid doses, or off-label for opioid-induced pruritus.

* Narcan can be administered intravenously (IV), intramuscularly (IM), subcutaneously (SUBQ), intranasally (IN), intraosseous (IO), or through an endotracheal tube (ETT).

Narcan dosage for opioid overdose

In the setting of a known or presumed opioid overdose, both the injection and intranasal formulation of Narcan can be used. The injection formulation can be administered intravenously, intramuscularly, or subcutaneously for quick reversal of opioid ingestion. The American Heart Association (AHA) recommends that in a life-threatening situation, after initiation of CPR, the use of intranasal or IM Narcan is preferred more than other routes of administration. 

For the intranasal route of administration, 4 mg or 8 mg as a single dose in one nostril should be administered. This may be repeated every two to three minutes in alternating nostrils until emergency medical response is available. The injectable formulation may also be administered intranasally as 2 mg (1 mg per nostril) if delivered with a mucosal atomization device.  

For any of the injectable routes, an initial dose of 0.4 mg to 2 mg should be administered, with repeat doses administered every two to three minutes. Lower initial doses of 0.1 to 0.2 mg may be considered in a patient with known opioid dependence to avoid acute withdrawal or if there are concerns of a concomitant stimulant overdose (e.g., cocaine). After initial reversal, it may be necessary to administer repeat dose(s) at later intervals (e.g., 20 to 60 minutes) depending on the type of opioid ingested. If after 10 mg of administration using an injectable route no response is observed, alternative reasons for respiratory depression should be considered.

Alternatively (and not as often employed), the injectable formulation of Narcan can be administered by nebulization at a dose of 2 mg diluted in 3 mL of normal saline. This route of administration is not recommended by the AHA, and switching to the above routes of administration should happen as soon as possible if repeat doses are warranted. This route of administration, albeit off-label in the first place, should never be employed in children.

Narcan dosage for opioid use disorder (naloxone challenge)

A Narcan (naloxone) challenge may be used by medical professionals in anticipation of initiating patients on long-term pharmacological therapies for treatment of opioid use disorder, as confirmation of resolution of physical dependence. Narcan can be administered via IV or SUBQ routes to patients with a negative opioid urine test (which should include buprenorphine and pentazocine, due to its tight binding to opioid receptors that may not be reversed by this challenge) and reporting a period of opioid avoidance. 

For IV administration, an initial dose of 0.2 mg should be administered. The challenge should stop if signs and symptoms of opioid withdrawal are present after a 30-second observation period; if no withdrawal signs or symptoms are present after 30 seconds, an additional dose of 0.6 mg of Narcan should be administered. The patient should be monitored for 20 minutes with vital signs, including high blood pressure and tachycardia (increased heart rate), being assessed as well as other adverse effects of opioid withdrawal, such as body aches. If withdrawal symptoms are present, the challenge should be terminated, the patient should be treated symptomatically, after which time the test can be repeated in another 24 hours. If no withdrawal symptoms are observed after the second dose, next steps for implementing medication therapy can be initiated.

For SUBQ administration, the total 0.8 mg of Narcan can be administered at one time. The patient should be monitored for 20 minutes, with vital signs being assessed as well as other symptoms for opioid withdrawal. As above, if withdrawal signs and symptoms are present, the patient should be treated symptomatically. The test may be repeated in another 24 hours as deemed appropriate by the medical professional. If no withdrawal signs and symptoms are observed, the patient may be initiated on an opioid abuse prevention treatment protocol.

Narcan dosage for opioid-induced pruritus 

Pruritus, or severe itching, is a common adverse reaction reported in 2% to 10% of patients treated orally with opioids for their analgesic effects—either long-term or short-term. The true incidence of pruritus depends on both the opioid used and its route of administration, with the incidence increasing when opioids are administered epidurally (the space around the spinal cord). The highest incidence reported is close to 100% when morphine is administered intrathecally (directly into the cerebrospinal fluid (CSF)).

Narcan may be administered in patients suffering from opioid-induced pruritis, although the use of Narcan for this indication is considered off-label. 

For this opioid-induced pruritis, Narcan is administered as a continuous intravenous infusion of 0.25 mcg/kg/hour—very low doses so as not to affect the analgesic effect of the opiate. This may be increased to higher doses of 2 to 3 mcg/kg/hour. A high dose is more likely to reverse the pain relief of the opiate. The lowest possible dose to balance reversal of pruritus while still achieving adequate pain control should be considered.

Narcan dosage for opioid-induced respiratory depression 

Respiratory depression is an effect of opioids, and in certain scenarios (such as subsequent relapses) patients experience this but still benefit from the analgesia provided. 

IV dosing for this respiratory depression starts at low doses of 0.02 mg to 0.2 mg with a plan to titrate up to a dose to balance reversal of the respiratory depression yet still providing the analgesic effects. Care should be used to avoid withdrawal in these patients.

An alternative route of administration that may be employed in intubated patients includes instillation into the bronchial tree through the endotracheal tube (ET). This is generally not recommended given only the anecdotal evidence available.

Narcan dosage for children

There is no unique formulation of Narcan for children. Narcan can also be administered by the same routes as employed with adults, although dosing differs significantly by indication. The absorption of Narcan via IM, SUBQ, and intranasal routes of administration may be erratic and/or delayed in pediatric patients. Also of difference is the off-label practice of intraosseous (IO; into bone) administration in this population when other routes of administration are not available.

Narcan dosage restrictions

Neither renal nor hepatic dysfunction warrant an alteration in Narcan dosage in adult or pediatric patients. 

Narcan dosage for pets

K9 officers have the potential to be exposed to opioids in the line of duty, and Narcan can be administered to canines either IM or intranasally to reverse the effects. The recommended dose employed for either route of administration is 4 mg as a first dose.

How to take Narcan

Administration of Narcan by lay rescuers in addition to healthcare providers is supported by the Food and Drug Administration (FDA). Often, patients needing Narcan are unable to administer it to themselves, so an understanding of recognizing an opioid overdose and administration of Narcan by all is a public health benefit. Administration intranasally is safe and very effective.

• Your doctor will tell you how much medicine to use. Do not use more than directed.

• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not freeze or expose to excessive heat. If the spray is frozen and is needed in an emergency, do not wait for the spray to thaw. Get medical help right away. However, the spray may be thawed for 15 minutes at room temperature, and it can still be used if it has been thawed after being frozen before. 

• Each nasal spray contains only one dose of naloxone. Do not prime or test the nasal spray. Hold the nasal spray with your thumb on the bottom of the plunger and your first and middle fingers on either side of the nozzle. Lay the patient on his or her back. Support the patient’s neck with your hand and let the head tilt back. Gently insert the tip of the nozzle into one nostril, until your fingers on either side of the nozzle are against the bottom of the patient’s nose. Press the plunger firmly to give the dose. Remove the nasal spray from the patient’s nose. Move the patient on his or her side (recovery position). Get emergency medical help right away. Watch the patient closely. If needed, you may give more doses every two to three minutes until the patient responds. Use a new nasal spray for each dose and spray the medicine into the other nostril each time. 

• This medicine is for use only in the nose. Do not get any of it in your eyes or on your skin. If it does get on those areas, rinse it off right away. 

• Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist for more drug information or medical advice if you have any questions.

• Your doctor or a pharmacist can tell you where to buy this medicine. It is available without a doctor’s order at most major pharmacies. 

• This medicine must be given to you (the patient) by someone else. Talk with people close to you so they know what to do in case of an emergency. 

• Ask your pharmacist about the best way to dispose of medicine that you do not use. 

Narcan dosage FAQs

How long does it take Narcan to work?

Typically, Narcan administered via the IV route of administration is going to work the quickest—in about two minutes. When administered endotracheally, intramuscularly, or subcutaneously, it may take up to five minutes for Narcan’s effect to occur. The onset of action of Narcan by inhalation using nebulization takes approximately five minutes and intranasally takes approximately eight minutes.

How long does Narcan stay in your system?

The effects of Narcan may last from approximately 30 minutes to 120 minutes, depending on the route of administration. IV administration will have the shortest duration of action. 

What is the maximum dosage for Narcan?

When administered to adults for the reversal of an opioid overdose, total doses exceeding 10 mg should be avoided as this should raise flags to evaluate for alternative causes of the patient’s distress. 

For a Narcan Challenge in adults, doses should not exceed 0.8 mg when administered either IV or subcutaneously. 

In adults being treated for opioid-induced pruritus reversal or respiratory depression from therapeutic opioid dosing, caution should be exercised to avoid exceeding recommended doses as a balance to minimize these side effects from the necessary analgesic effects. 

In pediatric patients, caution should be exercised when it comes to dosing Narcan as it differs significantly in most cases from the dosing employed in adults. 

What interacts with Narcan?

Narcan (naloxone) should not be used with Relistor (methylnaltrexone), Symproic (naldemedine), or Movantik (naloxegol) as they may enhance the adverse or toxic effects of Narcan (naloxone)—specifically the risk for opioid withdrawal. 

Is it safe to take Narcan during pregnancy?

Naloxone does cross the placenta, yet opioid use disorders are associated with adverse outcomes during pregnancy—both to the developing fetus and the mother. The use of naloxone for opioid use disorder during pregnancy is limited, so the risk of true withdrawal and abuse should be weighed against the risk of unwanted outcomes to the fetus or mother by the use of these medications. There is a growing body of evidence that demonstrates safety with this agent in a medication-assisted treatment option for opioid abuse during pregnancy, but current guidelines still recommend against their use. Safer and better-studied alternatives exist. In emergency situations, such in the setting of opioid overdose, The American College of Obstetricians and Gynecologists do recommend that naloxone be used in pregnant women to save the mother’s life, despite the possibility of fetal distress. 

Related resources for Narcan dosages:

• Naloxone, Substance Abuse and Mental Health Services Administration 

• Special circumstances of resuscitation, American Heart Association 

• Safety and efficacy of intranasally administered medications in the emergency department and prehospital settings, American Journal of Health-System Pharmacy

• Can nebulized naloxone be used safely and effectively by emergency medical services for suspected opioid overdose? Prehospital Emergency Care

• Antagonists in the medical management of opioid use disorders, The American Journal on Addictions

• Medications for opioid use disorder, Substance Abuse and Mental Health Services Administration 

• Non-analgesic effects of opioids: opioid-induced respiratory depression, Current Pharmaceutical Design

• Endotracheal naloxone reversal of morphine-induced respiratory depression in rabbits, Annals of Emergency Medicine

• Naloxone dosage and route of administration for infants and children, American Academy of Pediatrics

• Pediatric advanced life support, American Heart Association 

• PVM provides training on opioid-reversal drug Narcan to protect police dogs from opioid overdoses, Purdue College of Veterinary Medicine

• Narcan: Helping your canine partner, Missouri Veterinary Medical Association Animal Welfare Committee

• Having naloxone on hand can save a life during an opioid overdose, FDA

• Use of naltrexone in treating opioid use disorder in pregnancy, American Journal of Obstetrics and Gynecology

• Opioid use and opioid use disorder in pregnancy, The American College of Obstetricians and Gynecologists