Narcan (Naloxone) - Nasal

What Is Narcan?

Narcan (naloxone) is an opioid antagonist (blocker) used for emergency treatment of known or suspected opioid overdose. It is intended to be administered immediately in overdose situations involving opioids where breathing problems or unresponsiveness may be present.

Naloxone temporarily counteracts the effects of opioids, including respiratory depression (slowed or decreased breathing), sedation, and low blood pressure. It works by competing for the same opioid receptor binding sites and displacing opioid binding in the central nervous system.

Naloxone is available by prescription as a spray for nasal administration under the brand names Narcan and Kloxxado. It is also available generically. Other dosage forms of naloxone are available for administration via injection (intravenous by a healthcare provider or intramuscular by a non-medical person). 

People who are not under the care of a healthcare provider or may be unwilling to disclose substance use face barriers to naloxone prescription access. The Food and Drug Administration (FDA) continues with efforts to expand naloxone access to individuals and communities. Most U.S. states have passed laws that allow pharmacists to dispense Narcan to anyone via a statewide standing order, which replaces the need for an individual prescription. The FDA is also exploring making Narcan available over-the-counter (OTC, without a prescription).

Drug Facts

Generic Name: Naloxone

Brand Name(s): Narcan, Kloxxado

Drug Availability: Prescription

Therapeutic Classification: Opioid antagonist

Available Generically: Yes

Controlled Substance: N/A

Administration Route: Nasal

Active Ingredient: Naloxone

Dosage Form(s): Nasal spray

What Is Narcan Used For?

Naloxone treats respiratory and central nervous system depression from a known or suspected opioid overdose. Upon rapid administration, it helps restore normal breathing to someone whose breathing has slowed or stopped due to an overdose.

However, naloxone is not a permanent treatment for an overdose; overdose symptoms can return once the medication wears off. Therefore, once naloxone is administered, 911 should be called so the individual can receive prompt medical attention.

It is a good idea to ask a healthcare provider or pharmacist about naloxone if you are prescribed opioid treatment or have substance use disorder (SUD). Let your friends or loved ones know where it's kept, or ask a close member of the household to carry it.

How to Use Narcan

Use Narcan immediately if you suspect someone is having symptoms of an opioid overdose emergency (e.g., breathing difficulties, unresponsiveness). Narcan has no effect on people not taking opioids. The recommended dose for both adults and children is one spray into one nostril.

The following are general steps taken when administering Narcan. However, you should always have a healthcare provider or pharmacist provide detailed training to you and a caregiver or loved one on how to administer naloxone:

  1. Lay the person on their back.
  2. Remove Narcan nasal spray from its carton.
  3. Hold the Narcan nasal spray in one hand with your thumb at the bottom of the red plunger.
  4. Tilt the person’s head back and support the back of their neck.
  5. Insert nasal spray in one nostril until your fingers are at the bottom of the person’s nose
  6. Press the plunger firmly to give the dose of Narcan. Each Narcan nasal spray contains ONE DOSE only. 
  7. Remove Narcan nasal spray from the nostril after giving the dose.
  8. Call for emergency medical help right away. 
  9. Turn the person to lay on their side while waiting for help. 
  10. Watch the person closely. If they do not respond or relapse into overdose symptoms after the initial response, you may repeat steps one through seven after two to three minutes if another Narcan nasal spray is available. Use the other nostril. 


Store Narcan nasal spray in the blister package and carton provided. Keep it at room temperature and below 77 F. Protect it from exposure to light, freezing temperatures, and excessive heat. The nasal spray will freeze at temperatures below 5 F and will not work in an emergency situation.

Note the expiration date printed on the carton, and replace it with a new nasal spray when expired.

How Long Does Narcan Take to Work?

Narcan works within two to three minutes to help restore normal breathing for someone who overdoses on opioids. If there is no response after this time, you may administer another dose of Narcan in the opposite nostril if one is available.

What Are the Side Effects of Narcan?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

Common side effects of Narcan include:

  • Increased blood pressure
  • Constipation
  • Toothache
  • Muscle pain or spasms
  • Headache
  • Nasal dryness, swelling, and congestion
  • Dry skin

Severe Side Effects

Always call 911 for medical help immediately after administering naloxone.

Using Narcan in individuals who are dependent on opioids may result in opioid withdrawal. Symptoms of withdrawal may include:

  • Body aches
  • Fever and sweating
  • Increased blood pressure
  • Tachycardia
  • Shivering or trembling
  • Nervousness

Additionally, some people may exhibit aggressive behavior after an immediate reversal of an opioid overdose.

Report Side Effects

Narcan may cause other side effects. Call 911 immediately after naloxone administration.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Narcan Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For opioid overdose:
    • For nasal dosage form (Kloxxado™ spray):
      • Adults and children—At first, 8 milligrams (mg) (1 spray into one nostril). Another spray may be given into the other nostril every 2 to 3 minutes until the patient responds or until emergency medical assistance becomes available.
    • For nasal dosage form (Narcan® spray):
      • Adults and children—At first, 2 or 4 milligrams (mg) (1 spray into one nostril). Another spray may be given into the other nostril every 2 to 3 minutes until the patient responds or until emergency medical assistance becomes available.


There is insufficient data to determine whether naloxone causes significant birth defects in pregnant humans. Naloxone crosses the placenta and may induce withdrawal in the fetus. Due to this potential risk, the fetus may need to be monitored for signs of distress after Narcan administration.

It is not known if naloxone is excreted in human breast milk. Because it is not absorbed orally, it is not likely to affect a breastfeeding infant.

The safety and efficacy of naloxone have been established in children of all ages for known or suspected opioid overdose resulting in respiratory depression or central nervous system depression. Close monitoring is needed in opioid-dependent children since the use of Narcan may result in an abrupt reversal of opioid effects and cause acute opioid withdrawal syndrome.

Missed Dose

Because Narcan is only used in the event of an emergency, missed doses are not an issue. 

Overdose: What Happens If I Take Too Much Narcan?

Although naloxone will only work for opioid overdoses, it will not harm someone who has overdosed on other non-opioid drugs. Therefore, you should always administer it if you suspect someone may have overdosed on opioids.

It is not possible to overdose on naloxone, although people who are opioid-dependent may have increased withdrawal symptoms with multiple doses of naloxone.


Drug Content Provided and Reviewed by IBM Micromedex®

The effects of the opioid medicine may last longer than the effects of the naloxone. This means the breathing problems and sleepiness could come back. Always call for emergency help after the first dose of naloxone.

Severe opioid withdrawal symptoms may happen suddenly after receiving this medicine. These include body aches, a fever, sweating, runny nose, sneezing, goose bumps, yawning, weakness, shivering or trembling, nervousness, restlessness or irritability, diarrhea, nausea or vomiting, stomach cramps, fast heartbeat, and increased blood pressure.

Some types of opioid medications (eg, buprenorphine, pentazocine) may require larger or repeat doses of naloxone to reverse the opioid effects.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Use Narcan?

Do not use Narcan if you are allergic to naloxone or any of the inactive ingredients. 

What Other Medications Interact With Naloxone?

Naloxone use decreases or stops the efficacy of opioids, such as morphine or oxycodone, and can cause opioid withdrawal.

What Medications Are Similar?

Other opioid antagonists used to treat opioid overdose include:

  • Nubain (nalbuphine): Nalbuphine is available as an intravenous and injectable medication and has been used to reverse narcotic-induced respiratory depression.
  • Nalmefene: Nalmefene is an intravenous and injectable medication with similar efficacy in reversing opioid overdose symptoms and a longer duration of action compared to naloxone.

These medications are available only intravenously or as injections. Therefore, Narcan nasal spray is the preferred product for use in the community and by non-medically trained people.

Frequently Asked Questions

  • When should Narcan be used?

    Narcan should be given for known or suspected opioid overdose. Opioid overdose symptoms include excessive sleepiness, unresponsiveness, slow or shallow breathing, pinpoint pupils, or low blood pressure.

  • Do I need a prescription to obtain Narcan?

    Narcan is a prescription product. However, most states have passed laws that allow pharmacists to dispense Narcan to anyone via a statewide standing order, which replaces the need for an individual prescription. The FDA is also exploring making naloxone available OTC (without a prescription).

  • How does Narcan nasal spray differ from other forms of naloxone?

    Narcan nasal spray is easy for non-medically trained people to administer. Naloxone can also be given by injection into the muscle or vein. However, injectable naloxone is more commonly used in the medical setting. All forms of naloxone are effective for opioid overdose and differ slightly in response time.

  • What is the shelf life of Narcan?

    Narcan nasal spray has a shelf life (period to expiration date) of three years from manufacturing. Please follow the expiration date printed on the package.

How Can I Stay Healthy While Taking Narcan?

If you or a loved one uses prescription opioids or street narcotics, it is a good idea to have Narcan on hand in the event of an overdose. Consider also having more than one dose available in case multiple doses need to be given. Ask a healthcare provider or pharmacist for instructions for administering Narcan and ensure those who may be present in an overdose situation are also educated.

Naloxone access varies from state to state, so check out your state's rules for obtaining naloxone. In many states, a standing order allows healthcare providers to prescribe naloxone and for participating pharmacies to dispense it to family members, friends, or other individuals in a position to assist in an overdose situation.

Do not hesitate to administer Narcan for a suspected opioid overdose. Seek emergency medical care by calling 911 immediately after administering Narcan.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Narcan prescribing information.

  2. Food and Drug Administration. Statement on continued efforts to increase availability of all forms of naloxone to help reduce opioid overdose deaths.

  3. SAFE Project. State naloxone access rules and resources.

  4. Naloxone. In: Drugs and Lactation Database (LactMed). National Library of Medicine

  5. Centers for Disease Control and Prevention. Lifesaving naloxone.

  6. Food and Drug Administration. Nubain label.

  7. Edinoff AN, Nix CA, Reed TD, et al. Pharmacologic and clinical consideration of nalmefene, a long duration opioid antagonist in opioid overdose. Psychiatry Int. 2021;2(4),365-378. doi:10.3390/psychiatryint2040028

By Carrie Yuan, PharmD
Carrie Yuan PharmD is a clinical pharmacist with expertise in chronic disease medication management for conditions encountered in primary care.