Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Evzio
  2. Narcan
  3. Zimhi


Naloxone injection is used for emergency treatment of an opioid overdose or a possible overdose. It will temporarily reverse the effects of an opioid medicine. Some signs and symptoms of an opioid emergency are breathing problems (which can range from slow or shallow breathing to no breathing), extreme sleepiness, slow heartbeat, or not being able to respond, a very small (pinpoint) pupil in a person who is difficult to awaken.

This medicine is available only with your doctor's prescription.

This product is available in the following dosage forms:

  • Solution

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of naloxone injection in children.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of naloxone injection in the elderly. However, elderly patients are more likely to have age-related kidney, liver, or heart problems, which may require caution and an adjustment in the dose for patients receiving naloxone injection.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Morphine
  • Morphine Sulfate Liposome
  • Naldemedine
  • Naloxegol
  • Oxycodone
  • Oxymorphone

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Clonidine
  • Yohimbine

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Heart or blood vessel disease or
  • Kidney disease or
  • Liver disease—Use with caution. May make these conditions worse.

Proper Use

A home health caregiver or a family member will give you or your child this medicine. It is given as a shot under your skin or into a muscle.

This medicine should be given immediately upon when a suspected or known overdose of an opioid has occurred. This will help prevent serious breathing problems and severe sleepiness that can lead to death.

This medicine comes with patient instructions and a training device. Let your home health caregiver or family member read and follow the directions carefully. Ask your doctor if you have any questions.

To use:

  • Evzio® is available in 2 dosage strengths: 0.4 milligram (mg)/0.4 milliliter (mL) autoinjector or 2 mg/0.4 mL autoinjector. Zimhi™ is available in 5 mg/0.5 mL prefilled syringe.
  • It contains printed instructions on the device label. Evzio® also contains a speaker that provides electronic instructions which guides the user through each step of the injection.
  • Inject the medicine into the outer thighs, through clothing, if needed. If you are giving this medicine to a child younger than 1 year of age, you should pinch the thigh muscle while giving the medicine.
  • Do not use the medicine if it is cloudy, discolored, or has large particles in it.
  • This medicine can only be used one time. Do not remove the safety guard until you are ready to use it.
  • After giving the first dose to the patient, get emergency medical help right away.
  • Closely watch the patient for signs and symptoms of opioid emergency may return after several minutes.
  • Give a new naloxone injection every 2 to 3 minutes if symptoms returned and monitor the patient until emergency medical assistance becomes available.


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 injection dosage form (Evzio® autoinjector):
      • Adults and children—0.4 or 2 milligrams (mg) injected under the skin or into a muscle.
    • For injection dosage form (Zimhi™ prefilled syringe):
      • Adults and children—5 milligrams (mg) injected under the skin or into a muscle.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.


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 medicines (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.

Side Effects

Along with its needed effects, a medicine 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:

Incidence not known

  1. Agitation
  2. body aches
  3. chest pain
  4. coughing that sometimes produces a pink frothy sputum
  5. crying more than the usual (in babies)
  6. diarrhea
  7. difficult or trouble breathing
  8. excessive crying
  9. fast, pounding, or irregular heartbeat or pulse
  10. fever
  11. goosebumps
  12. increased or excessive unconscious or jerking movements
  13. irregular, fast or slow, or shallow breathing
  14. irritability
  15. nausea or vomiting
  16. nervousness
  17. pale or blue lips, fingernails, or skin
  18. restlessness
  19. runny nose
  20. seizures
  21. shivering
  22. sneezing
  23. sweating
  24. swelling in the legs and ankles
  25. trembling
  26. weakness
  27. yawning

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.