What Happens If You Use Drugs While on Sublocade?

Sublocade delivers a steady stream of buprenorphine from a solid depot under the skin, keeping your opioid receptors occupied around the clock. If you use opioids while on Sublocade, the most likely immediate result is that the high feels dramatically weakened or absent altogether, because buprenorphine is already sitting on the receptors those drugs need to activate. That blunted effect can tempt people into using dangerously large amounts to try to feel something, which is where the real medical emergency begins. The picture changes depending on which drug you use, how far into your dosing cycle you are, and whether other substances compound the risk.

How the Depot Keeps Working Between Injections

Unlike daily buprenorphine tablets or films that peak and trough every 24 hours, Sublocade creates a small solid mass under the skin of your abdomen after injection. The polymer slowly biodegrades over weeks, releasing buprenorphine by diffusion in a way that maintains sustained plasma concentrations throughout the entire monthly dosing interval.¹ This matters because it eliminates the daily decision to take your medication. Even if you stop showing up for appointments, the depot already in your body continues releasing buprenorphine for weeks or months after the last injection. That lingering reservoir is what makes Sublocade both protective and, in some scenarios, complicated.

The formulation uses a well-established polymer delivery system designed for sustained monthly dosing in the treatment of moderate-to-severe opioid use disorder.² Because the drug releases continuously rather than in a single burst, your buprenorphine blood levels stay relatively flat compared to the peaks and valleys of daily sublingual dosing. That flat profile is central to understanding what happens when other substances enter the picture.

Why Opioids Feel Blunted or Blocked

Buprenorphine is a partial agonist at the mu-opioid receptor, meaning it activates the receptor just enough to prevent withdrawal and reduce cravings but not enough to produce the intense euphoria of full agonists like heroin, fentanyl, or oxycodone. It also binds to those receptors with high affinity, making it difficult for other opioids to displace it. Research on optimizing treatment outcomes found that when buprenorphine plasma concentrations are sustained at roughly 2 to 3 ng/mL, corresponding to 70 percent or greater brain mu-opioid receptor occupancy, the blockade of opioid effects is strong enough to optimize outcomes for most patients.³ Some individuals, particularly those who had been injecting opioids, needed even higher concentrations to achieve the same level of blockade.

At higher buprenorphine doses, receptor availability drops to single-digit percentages. Modeling data showed that when buprenorphine reduced mu-opioid receptor availability to about 6 percent, self-administration of heroin at 50 mg and 100 mg doses was modestly decreased.⁴ The word “modestly” is important here. Buprenorphine blunts the subjective high and the rewarding feeling of opioids, but at lower occupancy levels or with very potent full agonists, some effects can still break through. Complete blockade is dose-dependent, and the margin is not absolute the way naltrexone blockade sometimes is.

A dedicated study of the 300 mg Sublocade dose tested this directly using hydromorphone, a strong opioid, given by intramuscular injection to participants with opioid use disorder. After the 300 mg injection, the subjective “liking” scores barely budged above placebo levels, and the reinforcing value of hydromorphone dropped in parallel. The blockade held through 12 weeks.⁵ In practical terms, if you use a standard dose of heroin, oxycodone, or hydromorphone while on Sublocade at the 300 mg level, you are unlikely to feel much of anything pleasurable from the drug. The money is wasted and the risk is real, but the high is mostly gone.

The Overdose Danger of Trying to Push Through

The blockade is the intended therapeutic effect, but it introduces a specific danger. When someone uses opioids and feels nothing, the instinct is to use more. If they keep escalating the dose, they are stacking respiratory depressant drugs in their body even though the subjective reward signal is absent. Buprenorphine’s occupation of the receptors prevents euphoria at moderate doses, but at very high doses of a full agonist, enough drug may spill over to non-occupied receptors or accumulate once buprenorphine’s binding eventually shifts. The result can be delayed or unpredictable respiratory depression.

Fentanyl complicates this further. Street-supply fentanyl is extraordinarily potent, and the doses circulating in illicit markets are often high enough to overwhelm even a reasonable degree of receptor blockade. Someone on Sublocade might use what they believe is a “test” amount of fentanyl, feel little, use more, and then face respiratory failure as the cumulative dose overpowers the partial agonist shield. The risk is compounded by the fact that street drugs are rarely pure, and what is sold as heroin or another opioid frequently contains fentanyl or its analogs at unpredictable concentrations.

There is also a timing dimension. Sublocade’s blood levels are highest in the first days after injection and taper slightly over the month. Although levels generally remain therapeutic throughout the interval, a person using opioids late in the cycle, just before the next injection is due, might have marginally lower buprenorphine levels and therefore slightly less blockade. This does not make it safe. It means the level of danger is somewhat unpredictable from one week to the next.

Alcohol, Benzodiazepines, and Other Sedatives

The blockade discussion so far applies specifically to opioids. Non-opioid substances interact with Sublocade through entirely different mechanisms, and several of them are more dangerous than people expect.

Alcohol and benzodiazepines (drugs like Xanax, Valium, or Klonopin) are central nervous system depressants that act on different receptor systems than opioids. Buprenorphine does nothing to block their effects. If you drink heavily or take benzodiazepines while on Sublocade, you get the full sedative effect of those substances on top of the respiratory depression buprenorphine itself causes. This combination is one of the leading causes of overdose death in people on any form of buprenorphine treatment. The buprenorphine in your system is already slightly suppressing your breathing drive. Adding another depressant compounds that suppression. Unlike with opioids, there is no blockade working in your favor here.

Stimulants like cocaine or methamphetamine are not directly blocked by buprenorphine either. You will feel their effects fully. The danger with stimulants is less about a pharmacological interaction and more about behavioral risk: stimulant use is associated with impaired decision-making that can lead to opioid relapse, and the combination of stimulant highs followed by sedative crashes can stress the cardiovascular system. Some people use stimulants and opioids together (a practice sometimes called “speedballing”), and the opioid portion of that combination is still subject to the blockade discussed earlier, but the stimulant portion is not muted at all.

Cannabis is a common question. Buprenorphine does not block or alter the effects of THC. Using cannabis while on Sublocade will feel the same as using it otherwise. The clinical significance is debated and largely depends on the individual’s treatment plan and the prescribing clinician’s perspective. Some treatment programs require abstinence from all substances including cannabis; others do not view cannabis use as a barrier to buprenorphine treatment.

Drug Interactions That Change Buprenorphine Levels

Beyond the question of whether you feel a high, certain drugs can alter how much buprenorphine is circulating in your blood, which affects both the blockade strength and side-effect profile. Buprenorphine is metabolized in part by the liver enzyme CYP3A4. If you take another medication that strongly inhibits CYP3A4, buprenorphine levels can rise. Modeling data for the depot injection predicted that daily co-administration of strong CYP3A4 inhibitors would increase buprenorphine exposure by roughly 33 to 44 percent and peak concentrations by about 17 to 28 percent.⁶ That is a mild increase, but it could tip someone into more pronounced side effects like sedation or nausea. Going the other direction, strong CYP3A4 inducers like rifampicin (an antibiotic used for tuberculosis) decreased buprenorphine exposure by about 28 percent, which could weaken the blockade.⁶

Common CYP3A4 inhibitors that people on Sublocade might encounter include certain antifungal medications (ketoconazole, itraconazole), some antibiotics (clarithromycin), and protease inhibitors used in HIV treatment. Grapefruit juice is a mild inhibitor but generally not potent enough to matter at the volumes most people consume. On the inducer side, the herbal supplement St. John’s Wort and certain anti-seizure medications like carbamazepine and phenytoin can lower buprenorphine levels. If you start or stop any of these while on Sublocade, your prescriber should know, because the depot’s slow release means you cannot simply adjust your buprenorphine dose day by day the way you could with tablets.

What Happens When You Need Real Pain Relief

One of the most common practical concerns for people on Sublocade is what happens if they break a bone, need surgery, or have some other source of acute pain. Because buprenorphine is sitting on most of your opioid receptors, standard doses of opioid painkillers will be significantly blunted. This can create a frustrating and frightening situation in an emergency room if the treating team is unfamiliar with buprenorphine therapy.

Clinical recommendations for managing pain in patients on buprenorphine have shifted over the years. Older guidance sometimes advised stopping buprenorphine before surgery, which risked precipitating withdrawal and relapse. Current practice recommendations suggest a different approach: continue buprenorphine through the perioperative or acute pain period and use a multi-modal strategy that combines non-opioid pain relievers (acetaminophen, NSAIDs, nerve blocks, ketamine) with short-acting opioids at higher-than-usual doses if needed.⁷ The key is that pain management is possible on Sublocade, but it requires clinicians who understand the pharmacology and are willing to individualize the plan.

If you are on Sublocade and facing elective surgery, the best move is to inform both your addiction medicine provider and your surgical team well in advance. Because the depot cannot simply be “turned off” the way sublingual buprenorphine can be discontinued, advance planning matters more. Carrying a card or medical alert notation indicating you are on extended-release buprenorphine can save critical time in an emergency.

Pregnancy and Sublocade

Using any substance during pregnancy while on Sublocade introduces considerations for both the parent and the developing fetus. Buprenorphine is one of the preferred medications for opioid use disorder during pregnancy, and there is limited but growing data on the depot injection specifically. In case reports of pregnant individuals who continued receiving the subcutaneous extended-release injection, serial drug screens remained positive for buprenorphine through delivery, and neither the mothers nor the neonates experienced withdrawal symptoms or adverse outcomes, with no birth anomalies found.⁸

Adding alcohol, tobacco, stimulants, or other substances on top of Sublocade during pregnancy layers additional fetal risks that buprenorphine does not protect against. The depot’s blockade shields against opioid effects specifically, not against the fetal toxicity of other drugs. Alcohol exposure during pregnancy carries its own well-documented risks, and stimulants are associated with placental complications. If you are pregnant and on Sublocade, the conversation with your obstetric and addiction medicine providers should address every substance you are using, not just opioids.

Late in the Cycle and After Discontinuation

A distinctive feature of Sublocade that surprises many patients is how long buprenorphine lingers after the last injection. Because the depot is a physical mass that takes months to fully degrade, measurable buprenorphine blood levels can persist for many weeks, sometimes several months, after you stop receiving injections. This extended tail offers a kind of unintentional taper that many people find smoother than stopping sublingual buprenorphine.

It also means that the blockade effect and the overdose risk equation persist long after your last appointment. If someone stops Sublocade and assumes they can use opioids freely a few weeks later, they may still have enough buprenorphine on board to partially block the high. But the levels are declining, which creates a window of unpredictable vulnerability. As buprenorphine clears, opioid tolerance drops, but the person may not realize how much tolerance they have lost. A dose they once survived easily can now be fatal. This transition period, when buprenorphine levels are falling but not yet gone, is one of the highest-risk windows for overdose after any form of buprenorphine treatment.

The extended pharmacokinetic tail also complicates drug testing. Buprenorphine will continue showing up on urine screens for weeks to months after the last injection. This is expected and should not be interpreted as ongoing illicit use if you have disclosed your Sublocade history to the testing provider. It can, however, create confusion in criminal justice, employment, or child custody settings where testing is done without clinical context.

Why Some People Still Use Despite the Blockade

From the outside, it seems irrational to keep using opioids when you know the high will be blunted. But substance use disorder involves deeply entrenched behavioral patterns that do not simply shut off because the pharmacological reward is blocked. Some people use out of habit, social pressure, or emotional distress. Others are testing the blockade, essentially checking whether the medication is “really working.” Still others are using non-opioid substances that Sublocade does not block at all.

The evidence on how well Sublocade reduces illicit opioid use in practice is encouraging but not absolute. The receptor occupancy data shows that at therapeutic levels, the pharmacological blockade is robust.³ But “blocking the high” and “eliminating drug use” are different outcomes. Comprehensive treatment generally pairs the injection with counseling, peer support, and management of co-occurring mental health conditions. The medication handles the pharmacology; the rest of the treatment handles the reasons a person reaches for drugs in the first place.

If you are on Sublocade and find yourself using opioids or other substances, that is clinical information your prescriber needs, not a reason to hide or to feel that treatment has failed. Adjusting the dose (from 100 mg to 300 mg, for instance), addressing untreated psychiatric symptoms, or adding behavioral interventions are all standard next steps. The blockade data from hydromorphone challenge studies confirms that the 300 mg dose provides durable suppression of opioid reward through at least 12 weeks.⁵ If the lower dose is not cutting it, moving up is a reasonable clinical conversation.