Quick Answer: Possibly. Taking Suboxone (buprenorphine/naloxone) about 24 hours after fentanyl can still cause precipitated withdrawal, especially after heavy or long-term fentanyl use. Waiting longer lowers the risk but doesn’t remove it, because fentanyl can linger in the body and behave differently from heroin. Many clinicians now use a low-dose start that begins while fentanyl is still in your system. Don’t time this on your own. Ask a prescriber or go to a clinic or ER that can start buprenorphine safely.
Safety: If you have stopped using fentanyl, your tolerance drops, and a return to use can cause an overdose. Keep naloxone (Narcan) on hand, never use it alone, and call 911 for an overdose. Never use more fentanyl to “treat” precipitated withdrawal.
Suboxone is a popular prescription medication that is used to treat opioid withdrawal and dependence. It contains buprenorphine and naloxone and is known for its ability to manage withdrawal symptoms and reduce cravings.
Buprenorphine is a partial opioid agonist that activates opioid receptors but to a lesser degree than other opioids like heroin or fentanyl. This results in fewer withdrawal symptoms without a euphoric high. Naloxone is an opioid antagonist that is used to reverse the symptoms of opioid overdose. It works by displacing opioid molecules from opioid receptors to restore breathing. The naloxone in Suboxone remains inactive unless Suboxone is abused or if someone takes an opioid while on the medication.[1]
Buprenorphine has a high binding affinity to opioid receptors, and it will displace opioid molecules if you take it too soon after an opioid. As a result, Suboxone can have negative and sometimes serious interactions if it is taken too soon after your last dose of fentanyl. Taking Suboxone too soon can result in a concerning condition called precipitated withdrawal. So when can you start taking Suboxone? And will you go into precipitated withdrawal if you use Suboxone 24 hours after fentanyl?
Most of the time, you should wait 12-24 hours after taking fentanyl to start taking Suboxone, but the exact timeframe can vary.
Fentanyl is stored in body fat. In people who use it heavily and regularly, it can build up and be released slowly over time. That means it can keep acting on opioid receptors, and keep a person’s body dependent, for much longer than the short half-life of a single dose suggests. When buprenorphine, which binds more tightly to opioid receptors, is taken while enough fentanyl remains, it can push the fentanyl off the receptors and trigger sudden, severe withdrawal. This is one reason waiting a fixed number of hours is less dependable with fentanyl than it was with heroin.
When Can You Start Taking Suboxone After Using Fentanyl?
Generally, doctors and pharmacists recommend that you wait at least 12-24 hours after using opioids before starting Suboxone.[2] The exact timeline depends on what kind of opioid you were using.
Fentanyl is a powerful and potent opioid. Some forms of fentanyl, such as the transdermal patch, are long-acting and can produce effects that last for up to 72 hours. However, other forms of fentanyl, such as illicit fentanyl that is smoked, snorted, or injected, are short-acting. Illicit fentanyl can produce effects that last for 2-3 hours. It has a half-life of 3-7 hours, so it can stay in your body for up to 24 hours.
If you take Suboxone less than 24 hours after your last dose of fentanyl, you are likely to go into precipitated withdrawal. It is best to wait at least 24 hours, more if you have been using the transdermal patch, before starting Suboxone.[3]
Understanding Precipitated Withdrawal
Precipitated withdrawal happens when buprenorphine (a partial agonist that binds very tightly) replaces a full opioid like fentanyl on the receptors too quickly. Instead of the gradual withdrawal that comes when opioids wear off, symptoms hit suddenly and are usually more intense.
| Type of symptom | Examples |
|---|---|
| Body | Muscle and bone aches, sweating, chills, goosebumps, runny nose, watery eyes, yawning, dilated pupils |
| Stomach | Nausea, vomiting, diarrhea, abdominal cramps |
| Heart and temperature | Fast heartbeat, high blood pressure, shakiness |
| Mind and mood | Severe anxiety, panic, agitation, restlessness, insomnia, intense cravings |
When does it start, and how long does it last?
Symptoms typically begin within minutes to a few hours of the buprenorphine dose, and can last many hours or longer, sometimes a day or more. Severity varies. Precipitated withdrawal isn’t usually life-threatening on its own, but it can be very distressing and can push people back toward using, so it needs medical attention.
Precipitated withdrawal is considered a medical emergency. If you think you are in precipitated withdrawal, you should seek help from your medical provider immediately.
What Is a Low-Dose (Micro) Start?
Because fentanyl makes standard timing less predictable, many clinicians now use a low-dose initiation. Instead of waiting for withdrawal to set in, the person begins with very small amounts of buprenorphine while still using their usual opioid. The amount is increased gradually over several days as the full opioid is stopped, which lets the buprenorphine build up without displacing everything at once. The approach is supported by a growing body of research and clinical experience, and it can help people who can’t tolerate waiting through withdrawal.
It must be done under a clinician’s supervision, with a plan for each day. Don’t try to design your own schedule or follow one from the internet.
If You Think You’re in Precipitated Withdrawal
- Contact your prescriber or go to an ER or urgent care right away. Don’t wait it out alone.
- Don’t take more fentanyl or other opioids to relieve it. That raises overdose risk, especially if your tolerance is low.
- Tell the clinician exactly what you used, when, and when you took buprenorphine. This helps them choose the right treatment.
- Expect supportive care. Clinicians may use medications for nausea, diarrhea, anxiety, and aches, and in some cases additional buprenorphine, which can help the receptors stabilize.
- Keep naloxone nearby, and call 911 for any sign of overdose. These signs include slow or stopped breathing, blue lips, or being unable to wake the person.
For free, confidential treatment referrals, call the SAMHSA National Helpline at 1-800-662-4357 (24/7), or use FindTreatment.gov.
How Long Should You Wait to Take Suboxone After Fentanyl?
There is no single safe number of hours for everyone. The right timing depends on how long and how heavily you used fentanyl, what form you used, and how you feel. A clinician decides.
| Situation | What clinicians commonly do |
|---|---|
| Short-acting illicit fentanyl, lighter or shorter use | Wait until you’re in moderate withdrawal (often guided by a COWS score) before a standard start. Many people need more than 24 hours |
| Heavy, daily, or long-term fentanyl use | Longer waits are often needed, and risk is higher even after 24+ hours. A low-dose start may be safer |
| Fentanyl patch (transdermal) | Longer-lasting, so a longer wait than for illicit fentanyl is typical |
| Unable or unwilling to wait through withdrawal | A low-dose initiation (sometimes called “microdosing”) can begin while you’re still using, under clinical supervision |
Is 12 hours enough? Almost never. Starting this early carries a high chance of precipitated withdrawal.
Is 24 hours enough? Sometimes, but not reliably, especially with heavy use. Fentanyl users can still develop precipitated withdrawal after 24 hours or longer, so 24 hours should not be treated as a guarantee.
How to Start Suboxone After Fentanyl Safely
- Start with a clinician, not a calendar. Many emergency departments, clinics, and telehealth providers can start buprenorphine, often the same day, and some offer low-dose starts.
- Be honest about your use. Tell them how long you used fentanyl, how often, what form, and when your last dose was. Include other substances like alcohol or benzodiazepines.
- Don’t take Suboxone that wasn’t prescribed to you, and don’t take a first dose early because you feel unwell.
- Ask about monitoring. In a clinic or detox setting, providers may use the COWS scale to decide the timing. SAMHSA notes fentanyl may need a higher COWS score and a lower first dose.
- Ask about other forms. Extended-release buprenorphine injections have their own starting requirements.
Questions to Ask Your Prescriber
- Should I wait, or is a low-dose start a better fit for my fentanyl use?
- What symptoms mean I should call you or go to the ER?
- What should I do if I have precipitated withdrawal?
- Can I get naloxone today?
- What support (counseling, follow-up) comes after I start?
At Moving Mountains Recovery in Randolph, NJ, we help clients access detox placement when medical withdrawal support is needed, support people using medication-assisted treatment, and provide Partial Care (PHP), Intensive Outpatient (IOP), and Outpatient (OP) care. Learn more about fentanyl addiction treatment. Call (973) 453-0317 or verify your insurance.
Find Out if Suboxone Treatment is Right For You
Suboxone may not be right for everyone. If you or a loved one are interested in Suboxone treatment or learning more about your treatment options, please contact our team at Moving Mountains Recovery today. We’re eager to help you start your recovery journey.
Frequently Asked Questions About Suboxone and Fentanyl
Will I go into precipitated withdrawal if I take Suboxone 24 hours after fentanyl?
Possibly. Waiting 24 hours lowers the risk compared with starting sooner, but it doesn’t remove it, especially after heavy or long-term fentanyl use, because fentanyl can linger in the body. Fentanyl users can still develop precipitated withdrawal after 24 hours or more, so timing should be set by a clinician.
How long should I wait to take Suboxone after fentanyl?
There’s no single safe number. Many clinicians wait until moderate withdrawal is present, often guided by a COWS score, and heavy daily users or patch users typically need longer. Some clinicians use a low-dose start that doesn’t require waiting. Ask a prescriber or clinic rather than counting hours on your own.
Why is precipitated withdrawal more common with fentanyl than heroin?
Fentanyl is stored in body fat and can be released slowly in people who use it heavily and regularly, so it may stay active longer than expected. That means more fentanyl may still be on the receptors when buprenorphine is taken, which raises the chance of buprenorphine pushing it off and triggering sudden withdrawal.
What is a low-dose (micro) start for buprenorphine?
It’s a clinician-supervised method where very small buprenorphine doses begin while you are still using your usual opioid, then increase gradually over several days as the full opioid is stopped. It can avoid the need to wait through withdrawal and lowers the chance of precipitated withdrawal. It should only be done under medical supervision.
What are the symptoms of precipitated withdrawal, and how long does it last?
Symptoms include muscle aches, sweating, chills, nausea, vomiting, diarrhea, runny nose, dilated pupils, fast heartbeat, anxiety, agitation, and cravings. They typically begin within minutes to a few hours of the buprenorphine dose and can last many hours or longer, sometimes a day or more. It needs medical attention.
What should I do if I’m in precipitated withdrawal?
Contact your prescriber or go to an ER or urgent care right away, and tell them exactly what you used and when. Don’t take more fentanyl or other opioids to relieve it, since that raises overdose risk. Treatment may include medications for nausea, anxiety, and aches, and sometimes additional buprenorphine.
Can I start Suboxone at home after fentanyl?
It’s safest to start under a clinician’s guidance, especially after fentanyl. Many clinics, emergency departments, and telehealth providers can start buprenorphine, sometimes the same day, and may choose a standard or low-dose approach for you. Don’t take Suboxone that wasn’t prescribed to you, or start a dose early.
Where can I get help starting Suboxone treatment?
Call the SAMHSA National Helpline at 1-800-662-4357 or use FindTreatment.gov for free, confidential referrals. Many ERs and clinics can start buprenorphine. Moving Mountains Recovery supports medication-assisted treatment and offers Partial Care, Intensive Outpatient, and Outpatient programs in New Jersey. Call (973) 453-0317.
References:
- National Library of Medicine: Suboxone: Rationale, Science, Misconceptions, Retrieved June 2023 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5855417/
- Addiction Science & Clinical Practice: Initiating buprenorphine to treat opioid use disorder without prerequisite withdrawal: a systematic review, Retrieved June 2023 from https://ascpjournal.biomedcentral.com/articles/10.1186/s13722-021-00244-8
- National Library of Medicine: Evidence of Buprenorphine-precipitated Withdrawal in Persons Who Use Fentanyl, Retrieved June 2023 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9124721/
- Substance Abuse and Mental Health Services Administration (SAMHSA): Buprenorphine Quick Start Guide, Retrieved June 2023 from https://www.samhsa.gov/sites/default/files/quick-start-guide.pdf
