Past opioid use does not always prevent you from taking naltrexone. However, it can be dangerous. If opioids remain in your body, naltrexone can trigger sudden withdrawal.
Share your opioid history with your prescriber. Before you start, list every medicine you take. Do not guess when it is safe to begin.
This guide covers opioid safety for those taking naltrexone for alcohol use disorder. For more info, read our guide to medications for alcohol use disorder. We are an editorial team that researches health topics. We are not a treatment provider, nor do we offer medical review.
Naltrexone and Opioid Use: Things to Check
Naltrexone is a medication approved to treat alcohol use disorder.[1] The extended-release injectable form of naltrexone is also approved for opioid use disorder, though approval and use depend on the specific formulation.[2] It works by blocking opioid receptors.[2] You may still use naltrexone for alcohol use disorder if you have used opioids in the past. But current or recent opioid use changes the safety picture. Our guide to naltrexone for alcohol use disorder covers side effects and how the medication fits into your recovery plan.
Overdose deaths are a serious issue in the U.S. In 2023, there were 105,007 drug overdose deaths.[3] These numbers show why safety matters. They are not a way to check naltrexone risk or effectiveness.
105,007
U.S. drug overdose deaths in 2023[3]
Knowing how naltrexone reacts with opioids is very important. Check our guide to medications for alcohol use disorder to find other choices.
What Happens When Naltrexone Meets Opioids
In the body, naltrexone blocks opioid receptors.[2] This reduces or stops the impact of opioid drugs.[4]
Pain meds with opioids can clash with naltrexone.[4] If you use naltrexone, opioids may not work the way you expect. Always discuss your pain care with your doctor.
| Situation | What May Happen | Why It Matters | Safer Next Step |
|---|---|---|---|
| Naltrexone blocks opioid receptors | Naltrexone may block opioid medicines used for pain.[5] | Pain treatment may be affected.[5] | Tell your prescriber you take naltrexone if you need pain care. |
| You take naltrexone after recent opioid use | If you are physically dependent on opioids or start naltrexone too soon after opioid use, severe withdrawal can occur.[5] | The risk depends on physical dependence and timing.[5] | For severe withdrawal symptoms, call 911 or go to the nearest emergency room now. If no emergency symptoms are occurring, contact your prescriber promptly. |
Why Timing Is Critical for Naltrexone Opioid Withdrawal
Precipitated withdrawal is a serious safety risk. It is not the same as regular withdrawal, which happens when someone physically dependent on opioids stops taking them.[5] Starting naltrexone too soon after opioid use, or while still physically dependent, can bring on severe withdrawal.[5]
This kind of withdrawal can be very bad.[5] Some people need hospital care, and intensive care may be needed in some cases.[5] Do not manage this at home. Do not pick a safe start date by yourself.
If you have severe withdrawal symptoms, call 911 or go to the nearest emergency room now. Speak to your prescriber before taking naltrexone if you have used opioids lately or are unsure of your last dose.[5] Your prescriber can check for recent opioid use and physical dependence before care begins.[5]
Does Your Opioid Past Change How You Start Naltrexone?
Past opioid use does not mean you need them today. However, a past history does not make starting naltrexone safe. The FDA label says naltrexone will cause withdrawal symptoms in people who are physically dependent on opioids.[5] Doctors must check for opioid dependence and recent use before you start.[5]
Your clinician will ask many questions. They need to know which opioids you have used. They also ask when you last used them. This includes prescriptions, store-bought products, and other uses. If the doctor is unaware of your opioid use, withdrawal can occur.[5] No single day count fits everyone. The safe timing relies on your specific situation and opioid. Starting too early can cause withdrawal bad enough for hospital care.[5]
Get ready for your visit with this checklist. You can also find more tips in our guide on asking your doctor about medication.
What to Tell the Prescriber
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Using Naltrexone with Opioid Pain Drugs
Taking naltrexone can stop opioid pain medicines from working.[5] Because of this, using opioids for pain relief becomes difficult. Please discuss this issue with your doctors.
- Tell your naltrexone prescriber. Share details about any upcoming surgery, dental work, or new pain issues.
- Notify all involved clinicians. Let surgeons, dentists, anesthesiology teams, and emergency staff know you take naltrexone. Tell them well in advance.
- Ask for a coordinated plan. Request that your care team work together to manage your pain safely.
- Disclose immediately in emergencies. If you have urgent pain, tell the staff you take naltrexone right away. Do not wait to call your usual prescriber first.
Do not stop or change your naltrexone dose on your own. Speak to your prescriber first if you want to change your medication plan.
For pain relief, doctors may try nonopioid options or regional pain methods. Your care team picks what is best for you. The facility must be ready for cardiopulmonary resuscitation.[5] Have written info about your naltrexone use with you so providers can treat you properly.[5]
Overdose Risk and When to Get Emergency Help
Naltrexone blocks the effects of opioids, but it does not protect you from an overdose if you use them anyway. A break from opioids can lower your body's tolerance.[5] Taking the same amount you used before may be unsafe because your body may not be able to handle it.
Trying to overcome the block or using opioids as the medication wears off can lead to a fatal overdose. Knowing this is key to staying safe with naltrexone and understanding opioid use.
Move quickly if you think someone is overdosing. Watch for signs like no response or breathing that is slow, shallow, or has stopped.
- Call 911 right away. Do not wait to see if the person wakes up.
- Use naloxone if you have it. Follow the instructions on the package. Naloxone can reverse an opioid overdose, but its effects may wear off before the opioid does.[6]
- Stay with the person. Monitor their breathing until emergency responders arrive.
Always seek professional help after any suspected overdose.
If you or a loved one has slipped up, remember that a lapse is not a moral failure. It is a sign that the current plan needs adjustment. Learn more about what to do after a relapse in our guide on managing setbacks with support. If you drank while on naltrexone, our guide to relapse on alcohol medication explains how to talk with your doctor. If you used opioids while on buprenorphine, our guide to relapse on buprenorphine covers how to reconnect with your treatment team.
Naltrexone and Opioid Use: Checking Safety of Both Forms
There are two main forms of naltrexone: an oral tablet and an extended-release injectable product.[7] They are given in different ways. Each form has its own safety questions for your care team. To understand what each option might cost you, see our guide to insurance coverage for naltrexone and how benefits vary.
The table below lists key differences. It is not a guide for taking opioid pain medicine safely. It does not say when you can start naltrexone. Only a prescriber can pick the right time for your history.
| Feature | Oral Naltrexone | Extended-Release Injectable Naltrexone |
|---|---|---|
| Formulation | Tablet taken by mouth | Microsphere suspension for injection |
| Administration | Taken by the patient at home | Administered by a healthcare professional |
| Specific Risks | General medication side effects | Injection site reactions, which are distinct from tablet risks |
| Starting After Opioid Use | Ask your prescriber how long you must be opioid-free to avoid precipitating withdrawal[5] | Ask your prescriber how long you must be opioid-free to avoid precipitating withdrawal[5] |
| Duration of Opioid Blocking | Ask how long the blocking effect lasts and how it may affect pain care[5] | Ask how long the blocking effect lasts and how it may affect pain care[5] |
| Planning for Procedures or Urgent Pain | Discuss with your prescriber how to manage pain if you need opioid relief during a procedure or emergency[5] | Discuss with your prescriber how to manage pain if you need opioid relief during a procedure or emergency[5] |
A healthcare professional gives the extended-release injectable product.[5] This form has risks at the injection site, including reactions where the shot goes in.
This medication blocks opioid receptors.[2] Effects can last after a dose, and the time varies by formulation and your situation.[5] Do not use this table to judge if opioid pain medicine is safe.
If you worry about how the medication affects your body, learn more about managing medication side effects in our related guide.
Consult Your Prescriber: A Safer Way to Move Forward
A quiz cannot show if opioids have left your body. It also cannot say if starting naltrexone is safe. That decision is made only by a doctor. Use this check to find out what to discuss with your prescriber.
What Should I Discuss Before Starting Naltrexone?
This self-check is for information only and isn't a diagnosis. It cannot determine safe timing for medication.
Emergency Warning: If you have seizures, severe confusion, hallucinations, a high fever or racing heart during withdrawal, signs of an overdose, or thoughts of suicide or self-harm, get emergency help now—call 911 or go to an emergency room. For suicidal thoughts, call or text 988; call 911 or go to an emergency room for immediate danger or if you cannot stay safe.
Action Steps Before Starting
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Frequently Asked Questions
What happens if you take naltrexone with opioids?
If you still have opioids in your body, naltrexone can cause sudden withdrawal. You may feel sick to your stomach, vomit, or have diarrhea. You might also have muscle aches and anxiety.[8] Do not try to guess if this is safe. Call your prescriber right away. If you have severe symptoms, call 911 or go to the nearest emergency room now.
What drugs should not be taken with naltrexone?
Tell your prescriber and pharmacist about all your medicines. Include prescription drugs, over-the-counter items, and other substances. Some products that do not look like painkillers may still contain opioids, such as certain cough syrups, anti-diarrheal medicines, or combination pain relievers. A clinician or pharmacist should check your complete medication list to identify these interactions, rather than relying on this article as an exhaustive list.
Does naltrexone block opioid receptors?
Yes, naltrexone blocks opioid effects at receptors.[2] It does not activate them. The drug does not remove opioids from your body. It also does not make using opioids safe. Never try to beat the block by taking more opioids.
How does naltrexone help with opioid addiction?
Naltrexone is one of the medications approved to treat opioid use disorder.[2] In the context of naltrexone and opioid use disorder, the medication works by blocking opioid receptors so that opioid drugs can no longer cause feelings of pleasure.[2] This differs from its role in alcohol use disorder, where it is also approved to help reduce cravings and heavy drinking.[2] Naltrexone is one treatment option among others, and it is often used alongside counseling or therapy. A prescriber must assess your specific health history and goals to determine if it is appropriate for you. They can help you compare this option with other treatments without providing specific dosing instructions here.
Why don't doctors like naltrexone?
Doctors do not have a general dislike for naltrexone. Clinicians look at your goals and health history first. They may delay starting naltrexone or choose another treatment if there is a risk of precipitated withdrawal because opioids are still in your body, if you need ongoing opioid pain treatment, or if other factors fit your specific treatment goals better. If a provider suggests a different option, ask why they chose it for you. This helps you understand the plan for your care.
Can I take pain meds while on naltrexone?
Do not assume opioid pain meds will work normally on naltrexone. The blocking effect can last for different amounts of time.[5] It depends on the form of the drug and your body. Do not stop or change naltrexone on your own. Talk to your prescriber first. Tell any doctor treating your pain that you take naltrexone so they can pick safer options.
