Compare naloxone vs. Naltrexone

Head-to-head comparisons of medication uses, side effects, ratings, and more.


Narcan (naloxone)

Prescription only

Vivitrol (Naltrexone)

Prescription only
Helps people breathe during an opioid overdose.

Narcan (naloxone) is used in an emergency if you think someone has overdosed on opioids. It only works for a few minutes and you'll need to call for emergency help.

Treats alcohol dependence and prevents relapse of addiction to opioids.

Vivitrol (Naltrexone) is good for treating opioid and alcohol dependence. It needs to be used as directed and can't be used with alcohol or opioid pain medications.

  • Can help save the life of someone who has overdosed on opioid drugs.
  • One brand of Narcan (naloxone) comes as a take-home auto-injection system with voice directions that talk you through giving Narcan (naloxone) in an emergency situation.
  • Available in two different forms: a tablet you take every day and as a shot your doctor gives you once a month.
  • Good for people who have a mild opioid use disorder and who are highly motivated, or who can be supervised as they take their medication.
  • Can be used with behavior modification therapy to treat opioid or alcohol use disorders.
  • Higher success rates are seen in people who use this under supervision.
  • The tablet is available as a generic.
  • Narcan (naloxone) is to be given right away and does not take the place of emergency medical care. Get emergency medical help right away after the first dose, even if the person wakes up.
  • Repeat dosing of Narcan (naloxone) may be required in some cases where the opioid hangs around in the body for a long time.
  • Narcan (naloxone) can cause acute withdrawal symptoms (body aches, anxiety, sweating, vomiting, fast breathing, shivering) if the person has been using opioids regularly.
  • People who try to take opioids after taking Vivitrol (Naltrexone) are at risk for opioid overdose and death since it takes a large amount of opioids to overcome the effects of Vivitrol (Naltrexone).
  • You won't be able to use any medications with opioids for pain relief since Vivitrol (Naltrexone) prevents them from working.
  • The shot is only available as brand name only, so it can be expensive.
  • Not a good choice if you have liver problems, depression, or are pregnant or breastfeeding.
Used for
  • Opioid overdose
Dosage forms
  • Injection
  • Pill
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Side effects
The Narcan (naloxone) FDA package insert doesn’t have numbers about how common side effects are.
9possible side effects
  • Nausea
  • Headache
  • Dizziness
  • Nervousness
  • Fatigue
  • Insomnia
  • Vomiting
  • Anxiety
  • Somnolence
See more detailed side effects
Risks and risk factors
  • Acute opioid withdrawal
    • Regular use of opioids
  • Heart and lung problems
    • History of heart problems
    • Taking medications that affect the heart
  • Seizures
    • History of seizures
    • Meperidine use
See more detailed risks and warnings
  • Opioid overdose
    • Prior use of opioid medications
    • Use of Vivitrol (Naltrexone)
  • Opioid withdrawal
    • Current use of opioid medications
    • New use of Vivitrol (Naltrexone)
  • Risk to unborn babies
    • Women of childbearing age
    • Breast-feeding while taking Vivitrol (Naltrexone)
  • Liver injury
See more detailed risks and warnings