Sublocade begins working within hours of the first injection, with buprenorphine levels in the blood reaching an initial peak around 24 hours after the shot. Most people notice a reduction in cravings and withdrawal symptoms within the first day or two. However, reaching a fully stable level of medication in your body takes longer, typically four to six months of consistent monthly injections.
What Happens in the First 24 Hours
When Sublocade is injected into the abdominal tissue, the liquid solution contacts bodily fluids and solidifies into a small, firm mass called a depot. This depot sits under the skin and begins releasing buprenorphine immediately. The initial burst of medication produces a peak blood level at a median of 24 hours after injection, which is fast enough to manage withdrawal symptoms and cravings starting on the first day.
The depot itself is typically a small, noticeable bump under the skin, roughly a few centimeters across. It gradually shrinks over the course of the month as buprenorphine is slowly released into the bloodstream. Some people can feel the lump for several weeks; this is normal and expected.
Building Up Over the First Two Months
The standard dosing schedule starts with two monthly injections at a higher dose (300 mg each), given about four weeks apart. These first two shots are designed to build up buprenorphine levels in your system quickly. After that, most people step down to a lower 100 mg maintenance dose each month, though some stay on the higher dose if their provider determines it’s needed.
Buprenorphine levels accumulate during those first two months. By the time you’ve had your second injection, blood levels are noticeably higher than after the first shot alone. If you stay on the 100 mg maintenance dose, those levels hold relatively steady from that point. If you continue on the 300 mg dose, levels keep climbing until they stabilize around the fourth monthly injection.
When Steady State Is Reached
Steady state, the point where the amount of medication entering your bloodstream roughly equals the amount leaving it, is reached at four to six months. This is when your buprenorphine levels become most consistent from day to day and week to week. Before that point, levels can fluctuate somewhat between injections, though typically not enough to cause withdrawal symptoms or strong cravings.
One reason Sublocade takes this long to fully stabilize is its extremely slow release. The apparent half-life of buprenorphine from the depot ranges between 43 and 60 days. That’s far longer than sublingual buprenorphine tablets or films, which clear from the body in about a day. The slow release is actually an advantage: it means medication levels don’t swing dramatically between doses, and it provides a long safety net if you’re late getting your next injection.
What You Need Before the First Shot
Before receiving Sublocade, you need to be on sublingual buprenorphine (the tablet or film placed under the tongue) first. The traditional approach requires at least seven days on sublingual buprenorphine to confirm you tolerate the medication well and are on a stable dose. A newer rapid induction approach, supported by a large randomized clinical trial, allows the first Sublocade injection as soon as one hour after a single small sublingual dose. This rapid method has shown comparable safety and effectiveness, and it removes a significant barrier for people who might otherwise drop out of treatment during a week-long transition period.
Short-Term vs. Long-Term Effects
The timeline breaks down into two distinct phases. In the short term, within the first one to three days, the initial release of buprenorphine from the depot is high enough to suppress withdrawal and reduce cravings. Most people feel meaningfully better in this window, especially if they were already stabilized on sublingual buprenorphine before switching.
The long-term benefit comes from consistency. Because the depot releases medication around the clock without any action on your part, you avoid the daily routine of sublingual dosing and the small dips in blood levels that can happen when a dose is late or missed. This steady delivery is one of the main reasons people switch to the injection form. The monthly formulation produces reliable blood levels that may work better for people who have had difficulty sticking with daily sublingual dosing.
How Long Medication Stays After Your Last Injection
If you stop Sublocade, buprenorphine doesn’t leave your system quickly. With a half-life of 43 to 60 days, measurable levels of buprenorphine remain in the blood for months after the final injection. This provides a built-in taper that many patients and providers find useful. Rather than an abrupt stop, the medication gradually decreases on its own, which can ease the transition if and when you decide to discontinue treatment.