How Long Do Opioids Stay in Your System?
Not all opioids clear at the same speed. Codeine can be gone from your urine in a couple of days. Methadone can still show up ten days later. Fentanyl sits somewhere in between — short detection window, but pharmacologically it's one of the most potent compounds in the class.
What you were taking matters. How much matters. How long you've been using matters. Your liver, your body size, your age — all of it feeds into the calculation. There's no single answer that applies to everyone, but there are solid ranges that give you a real picture of what's happening inside your body.
If you're trying to quit opioids, understanding this timeline isn't just about passing a drug test. It's about knowing when your body starts to feel the absence — and being prepared for it.
Detection Windows by Opioid Type
These are general ranges. Individual results vary based on the factors covered later in this article.
| Opioid | Blood | Urine | Saliva | Hair |
|---|---|---|---|---|
| Codeine | Up to 24 hours | 2–3 days | 1–4 days | 90 days |
| Morphine | Up to 12 hours | 2–3 days | Up to 4 days | 90 days |
| Oxycodone | Up to 24 hours | 3–4 days | Up to 48 hours | 90 days |
| Hydrocodone | Up to 24 hours | 2–4 days | 12–36 hours | 90 days |
| Heroin (as 6-MAM) | Up to 6 hours | 2–7 days | Up to 5 hours | 90 days |
| Methadone | 24–36 hours | 7–10 days | 1–10 days | 90 days |
| Fentanyl | Up to 12 hours | 1–3 days | Up to 48 hours | 90 days |
| Buprenorphine | 24+ hours | Up to 6 days | Up to 3 days | 90 days |
A few things worth noting here. Blood tests have short windows across the board — blood clears fast. Urine testing is the most common method used in clinical and legal settings, so that's usually the column people care most about. Hair testing is the great equalizer: regardless of which opioid, a 90-day window applies, which is why it's used in contexts where long-term detection matters.
Why Half-Life Matters
Half-life is how long it takes your body to eliminate half of the drug from your bloodstream. It directly controls how quickly you clear a drug — and how fast withdrawal begins after you stop.
Short-acting opioids like codeine have a half-life of around three hours. That means the drug clears fast. Urine can be clean in two to three days. But because it clears fast, withdrawal also kicks in sooner — often within 8 to 12 hours of the last dose.
Long-acting opioids like methadone have a half-life anywhere from 15 to 60 hours, depending on the individual. That's a massive range. It means methadone lingers — hence the 7–10 day urine detection window. It also means withdrawal is delayed. You might not feel it for 24 to 36 hours after stopping. When it does hit, it tends to be prolonged.
This directly connects to the opioid withdrawal timeline. The drug's half-life sets the clock. Knowing which opioid you were using tells you a lot about when symptoms are likely to start.
What Affects Detection Time
The table above shows averages. Your actual results can land shorter or longer depending on several factors.
Dose. Higher doses mean more drug and more metabolites. More metabolites take longer to clear.
Frequency of use. Occasional use clears faster than daily use. Your body handles an isolated dose differently than a system that's been processing opioids continuously for weeks or months.
Duration of use. Long-term, heavy use causes metabolites to accumulate in fat tissue and organs. They get released slowly back into the bloodstream and continue showing up in tests long after you'd expect them to be gone.
Liver and kidney function. Both organs do the heavy lifting in processing and excreting drugs. Compromised liver or kidney function slows clearance significantly.
Body mass and fat percentage. Some opioids are lipophilic — they bind to fat. People with higher body fat percentages may retain traces longer.
Age. Metabolism slows with age. Older adults generally clear drugs more slowly than younger adults.
Hydration. Urine concentration affects test results. Very dilute urine can push concentrations below detection thresholds. Highly concentrated urine can extend the detection window.
Metabolism speed. Genetic variation in liver enzymes — particularly CYP3A4 and CYP2D6 — affects how quickly different opioids are broken down. Some people are fast metabolizers. Others are slow. This is one reason why two people with identical use patterns can test differently.
The Fentanyl Complication
Fentanyl deserves its own section, and not just because it's statistically significant now. It's because the rules are different.
Fentanyl has a relatively short urine detection window — typically one to three days. Compared to methadone's week-plus window, that sounds manageable. But fentanyl's potency is in a different category. It's active at doses measured in micrograms. Standard immunoassay drug panels don't always detect it. Many tests designed to catch opioids were calibrated before fentanyl became common in the street supply. Specific fentanyl assays exist and are increasingly used in clinical settings, but a negative standard opioid screen doesn't confirm fentanyl is absent.
The street supply contamination issue is real. If you've been using street opioids — pills, powder, anything not dispensed directly from a pharmacy — there's a meaningful chance fentanyl has been present in your supply even if you didn't know it. This affects your pharmacological exposure, your physical dependence, and your withdrawal experience.
If your use has involved street-sourced opioids at any point, factor fentanyl into the picture. Don't assume a short detection window means a mild effect.
What This Means When You Stop
As opioids clear your body, withdrawal begins. That's the mechanics of it. Your brain and nervous system adapted to the presence of these drugs. When they're gone, there's a rebound.
The timing of that rebound tracks directly with the clearance timeline. Short-acting opioids: expect opioid withdrawal symptoms within hours. Long-acting opioids: expect a delay of one to several days before the peak arrives.
Understanding this doesn't make withdrawal easier. But it makes it less confusing. If you're 36 hours out from your last methadone dose and you're starting to feel it, that's not random — that's the pharmacology playing out on schedule.
For heavy use or long-term dependence, the transition period as opioids clear your system is when medical supervision matters most. The physical response can be intense, and there are clinical interventions that can make it safer and more manageable. That's not a lecture — it's just a practical consideration worth taking seriously.
If you want to keep track of where you are in the process, track your recovery day by day. It helps to have a concrete reference point.
Frequently Asked Questions
How long does oxycodone stay in your urine?
For most people, oxycodone is detectable in urine for three to four days after the last dose. Heavy or long-term use can push that window longer. A single occasional dose may clear faster. Standard urine immunoassay panels typically detect oxycodone, though some basic panels test only for morphine-type opioids — a specific oxycodone test may be needed for confirmed detection.
Does methadone show up on a standard drug test?
Standard opioid panels often don't detect methadone because it has a distinct chemical structure from morphine-based opioids. A specific methadone test needs to be ordered. If you're in a program or legal situation where your methadone use is known and sanctioned, this matters for how results are interpreted. If a test comes back negative for opioids but you've been using methadone, it's likely because methadone wasn't included in the panel — not because you've cleared it. Methadone stays in urine for seven to ten days.
How long after stopping opioids does withdrawal start?
It depends on which opioid. Short-acting opioids — codeine, heroin, oxycodone, hydrocodone — withdrawal typically begins within 8 to 24 hours of the last dose. Long-acting opioids like methadone may not trigger noticeable withdrawal for 24 to 72 hours. Buprenorphine sits in the middle. The opioid withdrawal timeline breaks this down in more detail, including when symptoms tend to peak and when they start to ease.
Written by 180 - Benjy. I write about quitting, what actually happens to your body, and what makes it harder or easier. No fluff. If something here is wrong or outdated, I want to know.