Percocet (oxycodone combined with acetaminophen) typically stays in your system for about 1 to 1.5 days after your last dose, based on standard urine testing. But the answer depends on what you mean by “in your system,” whether you’re asking about how long the effects last, how long until it’s fully eliminated, or how long it shows up on a drug test. Each of those timelines is different.
How Long the Effects Last
Percocet is an immediate-release formulation, meaning it’s designed to work quickly and wear off relatively fast. Pain relief from a single dose typically lasts 3 to 6 hours. That’s the window where you’ll feel the drug actively working. After that, the medication is still in your body and being broken down, but it’s no longer providing meaningful pain control.
This is an important distinction. The drug doesn’t vanish from your bloodstream the moment you stop feeling its effects. Your liver is still processing it for hours afterward.
How Long Until It’s Fully Eliminated
Percocet contains two active ingredients, and each clears your body at a different rate.
The oxycodone component has an elimination half-life of roughly 3 to 4 hours in most healthy adults. That means half the drug is gone from your blood in about 3 to 4 hours, half of what remains is gone in another 3 to 4 hours, and so on. It generally takes 4 to 5 half-lives for a drug to be considered fully eliminated, which puts total clearance of oxycodone at roughly 15 to 20 hours for a single dose.
The acetaminophen component clears faster, with a half-life of 1.5 to 2.5 hours at normal doses. It’s essentially gone within 8 to 12 hours. However, if your liver is struggling (from heavy use, liver disease, or overdose), acetaminophen’s half-life can stretch to 4 to 8 hours.
Drug Test Detection Windows
If you’re asking because of an upcoming drug test, here’s what matters: oxycodone is detectable in urine for about 1 to 1.5 days after your last dose. That window can shift depending on the test’s cutoff threshold and your individual metabolism.
One detail that catches people off guard: standard urine drug panels screen for opiates like morphine and codeine, and oxycodone often screens negative on those tests. It requires a specific test targeting oxycodone directly. Many employers and clinics now use expanded panels that include oxycodone, but not all do. If someone is testing for it specifically, the 1 to 1.5 day window applies.
Hair and blood tests have different windows. Blood tests detect oxycodone for roughly 24 hours, while hair tests can pick it up for up to 90 days, though hair testing is far less common in routine screening.
Factors That Slow Clearance
That 1 to 1.5 day detection window is an average. Several factors can push your personal timeline longer.
- Sex: Women tend to have oxycodone blood concentrations about 25% higher than men, even after adjusting for body weight. This means the drug lingers somewhat longer in women’s systems.
- Liver health: Your liver does the heavy lifting in breaking down oxycodone. In people with moderate to severe liver disease, oxycodone levels in the blood nearly double (a 95% increase in overall drug exposure). If your liver isn’t functioning well, clearance slows significantly.
- Kidney function: Impaired kidneys raise oxycodone concentrations by about 50%, since the kidneys are responsible for flushing out the drug’s byproducts.
- Genetics: About 5% to 10% of white individuals carry gene variants that reduce the activity of a key liver enzyme involved in processing oxycodone. If you’re a “poor metabolizer,” your body breaks the drug down more slowly, extending how long it stays detectable.
- Chronic use vs. a single dose: If you’ve been taking Percocet regularly, the drug accumulates in your tissues. A single dose clears predictably, but weeks or months of daily use means your body has more stored oxycodone to process, potentially extending detection beyond the standard 1 to 1.5 day window.
The Acetaminophen Risk Most People Miss
Because Percocet contains acetaminophen, there’s a safety ceiling that has nothing to do with oxycodone. The total daily intake of acetaminophen should not exceed 4,000 milligrams, and liver damage is most common when people cross that line. The risk goes up when you’re taking other products that also contain acetaminophen (cold medicines, headache pills, sleep aids) without realizing they overlap. Check labels for “acetaminophen” or “APAP” on anything else you take.
When Withdrawal Symptoms Start
If you’ve been taking Percocet regularly and stop, your body notices once the drug starts clearing. For short-acting opioids like oxycodone, withdrawal symptoms typically begin 8 to 24 hours after the last dose. Early symptoms include anxiety, muscle aches, sweating, and insomnia. The acute phase usually lasts 4 to 10 days, with the worst discomfort peaking around days 2 and 3.
This timeline aligns with the drug’s elimination. As oxycodone drops below the level your body has adapted to, your nervous system rebounds, producing symptoms that are essentially the opposite of the drug’s effects: pain sensitivity instead of pain relief, restlessness instead of sedation, diarrhea instead of constipation.