Other medications

What is Naltrexone?

Learn about the benefits of FDA-approved medicine, Naltrexone, and why it isn’t always the best starting point compared to Suboxone®.

Ophelia team
Naltrexone medicine bottle
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Fact checked by
Arthur Robin Williams, MD

Naltrexone is an FDA-approved medicine used to help people dealing with opioid dependency. It works by blocking and reducing the functionality of the body’s opioid receptors to prevent the people who use drugs (PWUD) from feeling the drug’s euphoric effects that ultimately reinforce addictive behaviors. The medication can be taken orally or by injection and is only available by prescription.

This drug is typically used as a part of a larger program for managing addiction. It works best when an individual hasn’t used opioids for one to two weeks and is no longer physically dependent on them. While this medication can be beneficial, it isn’t always the best starting point compared to a treatment with a lower barrier to entry, like Suboxone®. People using Naltrexone need to start from a place of not being dependent, while Suboxone reduces cravings over time, making it more suitable for people who are just starting treatment.

What are the side effects of naltrexone?

Like any medication, naltrexone can produce side effects that may require medical assistance. Your doctor can inform you about the severity of a particular side effect and decide whether another treatment would be safer.

Some side effects are more serious than others, and not every side effect is equally common. Among the most common side effects in opioid users are:

  • Reduced energy levels
  • Muscle and joint pain
  • Headaches
  • Anxiety and nervousness
  • Trouble sleeping
  • Nausea or upset stomach

Side effects seen in less than 10% of reported cases include:

  • Constipation or diarrhea
  • Loss of appetite
  • Irritability
  • Dizziness 
  • Excessive thirst
  • Sadness 
  • Rash on the skin
  • Chills
  • Delayed ejaculation

Other potential side effects of naltrexone include the symptoms of withdrawal syndrome, such as irritability, sweating, shaking, and dysphoria. In serious cases, some patients experience depression and suicidal thoughts. If you experience any side effects while taking naltrexone, reach out to your doctor immediately for guidance.

What should be avoided when taking naltrexone?

Continued drug and alcohol use

Avoid taking any opioid drugs while on naltrexone. Remember that this medication decreases the euphoric feeling opioids provide, so it can be tempting to take more to produce the desired high. But this makes overdosing much more likely—and this could lead to coma, other serious conditions, or even death. 

Additionally, avoid becoming intoxicated. If you drink alcohol, taking naltrexone will prevent you from feeling buzzed but will not prevent the physical effects of inebriation. This makes driving and other activities dangerous and potentially deadly.


Before taking naltrexone, discuss any known allergies with your doctor and be thorough and forthcoming with your medical history. When taking the medicine, avoid using any dosage amount or schedule outside your doctor’s recommendations.

There are a variety of medicines that should not be taken while on naltrexone, including opioid pain and cough medications and certain sedatives and tranquilizers known as central nervous system (CNS) depressants. Using prescription opioids while on naltrexone will make the medication less effective. Conversely, naltrexone can amplify the effects of CNS depressants, leading to unsafe levels of sedation.

Your doctor will evaluate your medical history and decide whether naltrexone is an appropriate treatment. Due to possible adverse drug interactions, let other medical providers—including

lab technicians and mental health and dental professionals—know that you’re taking this medicine.

Improper use and storage

Do not change any part of your treatment plan without consulting your care team. This includes skipping doses and doubling up later and increasing or decreasing the dosage amount. Treatment plans with multiple elements, such as therapy in combination with medication, need to be followed carefully for the best possible outcomes.

Naltrexone also needs to be stored and administered properly. It should be kept away from children and stored in a closed container at room temperature. Medicine should not be stored anywhere with excess heat, cold, or direct sunlight. Properly dispose of the medication if it expires.

It’s also important not to give your medicine to anyone else. Naltrexone is a prescription medicine, so it must be administered by a certified medical professional.

Ignoring side effects

Since naltrexone has a wide range of potential side effects, report any physical changes or abnormal sensations to your doctor immediately. If you’re experiencing strong or unexpected feelings, such as depression, anger, restlessness, or fear, tell your doctor right away so they can change your treatment plan.

MAT with Ophelia

Medication-assisted treatment (MAT) is safe and effective—especially when you can receive care on your terms. Ophelia’s Suboxone-based treatment is designed to help you manage withdrawal symptoms and cravings so you can begin your treatment journey as soon as you feel ready.

After a brief consultation call, we’ll pair you with a support team, including clinicians and a care coordinator. All appointments are conducted remotely, giving you the chance to seek treatment from the comfort and privacy of home.

Find out if you’re a candidate for our program today.


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