OxyContin’s active ingredient, oxycodone, has an elimination half-life of roughly 4 to 5 hours, meaning the drug itself clears from your bloodstream within about 24 hours after your last dose. But its metabolites linger much longer, and those are what drug tests actually detect. Depending on the type of test, oxycodone can show up for anywhere from 1 to 4 days in urine, and potentially longer in hair.
How Your Body Processes OxyContin
OxyContin is a controlled-release formulation, so the tablet slowly releases oxycodone over about 12 hours. Once absorbed, your liver breaks the drug down into three key byproducts: noroxycodone (the primary metabolite), oxymorphone, and noroxymorphone. About 72% of a dose gets excreted through urine over 48 hours, but only around 9% of that is unchanged oxycodone. The rest is those metabolites, with noroxycodone alone accounting for roughly 23% of the dose.
This matters because drug tests screen for both oxycodone and its metabolites, particularly oxymorphone. Even after the parent drug has left your blood, these breakdown products remain detectable in urine for days.
Detection Windows by Test Type
Different drug tests have very different detection windows:
- Urine: 2 to 4 days after the last dose. This is the most common method for workplace and clinical testing. The standard cutoff used in federally regulated testing (including DOT screenings) is 100 ng/mL for both oxycodone and oxymorphone.
- Blood: Up to 24 hours. Blood tests capture the active drug window and are typically used in hospital or emergency settings, not routine screening.
- Saliva: 1 to 4 days, though saliva testing for oxycodone is less standardized and less commonly used.
- Hair: Up to 90 days. Hair testing captures a long history of use but won’t detect a single recent dose reliably.
If you’ve been taking OxyContin regularly rather than a single dose, expect the upper end of these ranges. With repeated dosing, oxycodone reaches steady-state levels in your blood within 24 to 36 hours, according to the FDA-approved label. That buildup means there’s more drug and more metabolites to clear once you stop.
Factors That Slow Clearance
Not everyone clears oxycodone at the same rate. Several factors can push the detection window longer.
Age
Older adults eliminate oxycodone significantly more slowly. Research published in the British Journal of Anaesthesia found that the elimination half-life increases by up to 30% in elderly patients compared to younger adults. In practical terms, the half-life rises from about 3.8 hours at age 25 to 4.6 hours at age 85. That translates to roughly 20% higher drug concentrations in older adults at the same dose, and a longer window before the drug fully clears.
Kidney and Liver Function
Your kidneys handle the bulk of excretion, so impaired kidney function directly extends how long oxycodone and its metabolites stay in your system. Studies in patients with end-stage kidney disease show prolonged elimination half-lives due to both reduced clearance and increased distribution of the drug throughout the body. Liver disease has a similar effect, since the liver is responsible for breaking oxycodone into its metabolites in the first place. When that process slows, the parent drug lingers longer in your blood.
Body Weight and Metabolism
Body composition plays a role too. Lean body mass influences how the drug distributes and how quickly it’s cleared. People with higher body fat may retain oxycodone slightly longer because it can accumulate in fatty tissue. Genetic differences in liver enzymes (specifically CYP2D6, which converts oxycodone to oxymorphone) also create meaningful variation between individuals. Some people are naturally fast metabolizers, while others process the drug more slowly.
Dose and Duration of Use
Higher doses mean more drug to eliminate, which extends the timeline. Chronic use is even more impactful. When you take OxyContin daily, the drug and its metabolites accumulate in your tissues. Someone who has been on a high dose for months will test positive for longer than someone who took a single tablet.
When Withdrawal Symptoms Start
Because OxyContin is a controlled-release formulation, withdrawal symptoms typically begin 12 to 48 hours after the last dose. The worst symptoms, including muscle aches, nausea, anxiety, and insomnia, usually peak between 24 and 96 hours after stopping. Most people start to feel noticeably better within 5 to 7 days, though some lingering effects like sleep disruption and low energy can persist longer.
The withdrawal timeline roughly tracks the drug’s clearance from your system. As blood levels drop below a certain threshold, your body starts reacting to the absence of the opioid it had adjusted to. This is why the onset of withdrawal is a useful real-world signal that the drug is leaving your system, even without a lab test.
What This Means for Drug Testing
For a standard urine drug test, you can reasonably expect oxycodone to be detectable for 3 to 4 days after your last OxyContin dose if you’ve been taking it regularly. A single dose may clear faster, potentially within 2 to 3 days. If you’re older, have kidney or liver problems, or have been on a high dose for an extended period, add extra time to those estimates.
Keep in mind that older immunoassay screening tests (the initial pass in most drug panels) sometimes miss oxycodone entirely, since they were designed to detect morphine-type opioids. Newer panels specifically target oxycodone and oxymorphone at the 100 ng/mL cutoff. If a screening comes back positive, a confirmatory test using more precise lab methods will verify the specific drug present.