OxyContin (extended-release oxycodone) has an elimination half-life of about 4.5 hours, meaning it takes roughly 22 to 25 hours for a single dose to clear your bloodstream almost completely. But “in your system” can mean different things depending on whether you’re asking about the drug’s active effects, a standard drug test, or complete metabolic clearance. Detection windows range from about 48 hours in saliva to 2 to 3 days in urine, and potentially up to 90 days in hair.
How Long the Effects Last
OxyContin is a controlled-release formulation designed to release oxycodone gradually over about 12 hours. Blood levels peak around 2.5 to 3.2 hours after you take a tablet, which is slower than immediate-release oxycodone (which peaks in roughly one hour). The pain-relieving effects of a single OxyContin dose typically last 10 to 12 hours, which is why it’s prescribed on a twice-daily schedule.
Even after the pain relief fades, the drug is still circulating. With a half-life of 4.5 hours, roughly half the oxycodone from your last dose remains in your blood after 4.5 hours, a quarter after 9 hours, and so on. It generally takes about five half-lives for a drug to drop below detectable levels in the blood, which puts full clearance at around 22 hours for a single dose. People who take OxyContin on a regular schedule will have higher baseline levels, and clearance takes longer.
Detection Windows by Test Type
Drug tests don’t just look for oxycodone itself. They also detect its breakdown products (metabolites), which linger in the body after the active drug is gone. Here’s how long oxycodone typically shows up on each type of test:
- Urine: 2 to 3 days after the last dose. This is the most common screening method. Up to 19% of oxycodone is excreted unchanged in urine, and up to 50% appears as a conjugated form, giving urine tests a reliable detection window.
- Blood (serum): Up to 2 to 3 days, similar to urine, though blood tests are less commonly used for routine screening.
- Saliva: Up to 48 hours. Oral fluid tests have a shorter detection window than urine or hair but are convenient and harder to tamper with.
- Hair: Up to 90 days. Hair follicle tests capture a much longer history of drug use but are typically reserved for specific situations like workplace screening or legal cases.
These are general ranges. Your actual detection window depends on several personal factors.
What Affects How Fast You Clear It
Oxycodone is processed primarily in the liver by two enzyme families. One pathway (responsible for about 45% of breakdown) converts oxycodone into an inactive metabolite. A second pathway (about 11% of total breakdown) converts it into oxymorphone, which is itself an active painkiller with strong effects. The remaining drug is processed through additional minor pathways before being excreted by the kidneys.
Several factors can speed up or slow down this process:
Liver and kidney function. Because the liver does the heavy lifting on metabolism and the kidneys handle excretion, impairment in either organ slows clearance significantly. People with reduced kidney function can accumulate active metabolites in their blood, which extends both the drug’s effects and its detection window. Liver disease has a similar impact by reducing the speed of initial breakdown.
Genetics. The liver enzymes that process oxycodone, particularly CYP2D6 and CYP3A4, vary significantly from person to person based on genetics. Some people are “poor metabolizers” who break the drug down slowly, leading to higher blood levels that persist longer. Others are “ultra-rapid metabolizers” who clear it faster than average. These genetic differences can meaningfully shift how long oxycodone remains detectable.
Age, body composition, and hydration. Older adults generally metabolize drugs more slowly due to declining liver and kidney function. Higher body fat percentages can also influence how the drug distributes and how quickly it’s eliminated. Differences in gender, hydration status, and overall health contribute to the variability between individuals.
Dose and duration of use. A single OxyContin tablet clears much faster than weeks of regular use. Chronic use allows oxycodone and its metabolites to accumulate in tissues, extending the time needed for complete elimination. Someone who has been taking OxyContin twice daily for months will test positive for longer than someone who took one dose.
OxyContin vs. Immediate-Release Oxycodone
OxyContin’s controlled-release design gives it a slightly longer half-life (4.5 hours) compared to immediate-release oxycodone (3.2 hours). This difference matters for how long the drug is active in your body, but it has a relatively modest effect on total detection time. The same metabolites show up on drug tests regardless of which formulation you took, and the urine detection window of 2 to 3 days applies to both.
The practical difference is that OxyContin releases oxycodone more slowly, so blood levels stay elevated for a longer stretch after each dose. If you’re trying to estimate when the drug will no longer be active, count roughly 22 to 25 hours from your last OxyContin dose versus 16 to 20 hours for immediate-release oxycodone.
Withdrawal Onset as a Clearance Signal
For people who are physically dependent on oxycodone, withdrawal symptoms offer a rough biological signal that the drug is leaving the system. Withdrawal from short-acting oxycodone formulations typically begins 6 to 12 hours after the last dose. For longer-acting opioids like methadone, onset may not occur for 1 to 3 days. OxyContin falls somewhere in between due to its extended-release design, with most people noticing early symptoms within 8 to 16 hours of their last dose. The onset of withdrawal doesn’t mean the drug is undetectable on a test, but it does indicate that active blood levels have dropped below the threshold your body has adapted to.