By Lauren Smith

Last updated: 09 February 2024 & medically reviewed by Dr. Jenni Jacobsen

Percocet, a prescription opioid combining oxycodone and acetaminophen, is commonly abused and can be identified in many drug tests. Usually, it’s eliminated from users’ bloodstreams within 24 hours, but metabolites can linger in saliva and urine for two to four days and can be detected by hair follicle testing for three months.

Percocet half-life

Percocet is a prescription analgesic made up of the opioid oxycodone and the mild medicine cabinet painkiller acetaminophen (paracetamol).

The average half-life of a single dose of immediate-release formulations of oxycodone (the type used in Percocet) is relatively short at just 3.5 hours.[1] That means it takes 3.5 hours for the blood concentration of the drug to fall to half its initial level.

For people using Percocet for pain relief, this means they need to take doses regularly: once every six hours is common. People who abuse Percocet and are heavily dependent may begin feeling withdrawal symptoms as quickly as four hours after their last use of the medication.

The half-life of acetaminophen is around 2 to 3 hours.[2]

How long does Percocet stay in your system?

It usually takes around 5 half-lives for a substance to be mostly (97%) cleared from your bloodstream. This means oxycodone will be mostly eliminated from your body in 17.5 hours. However, traces and metabolites may remain in the bloodstream for longer and may also be detected in urine, saliva, and hair.

Acetaminophen will be eliminated from your bloodstream in 10 to 15 hours. However, this is less important because acetaminophen—most commonly known under the brand name Tylenol—is an extremely common over-the-counter medicine with few adverse effects, except in overdose, and no potential for abuse. No common drug tests search for acetaminophen, as there are no penalties for using it.

How quickly does Percocet take effect?

You also have to consider how long Percocet takes to enter your bloodstream. This will determine how quickly you feel its effects and also how quickly it’s eliminated from your body. 

Percocet comes in pills, and people who take it as prescribed for legitimate medical reasons will swallow them. They’ll then be absorbed through the digestive system and processed by the liver before entering the bloodstream. This can take 30 minutes to an hour, or even longer if you take the Percocet with a full meal.

People who abuse Percocet may employ other methods that deliver a faster and more intense high. They may crush up the pills and snort them. The drugs are absorbed through a mucus membrane in the nasal cavity in a matter of seconds, and they enter the bloodstream and then hit the brain almost immediately.

Others dissolve Percocet into water and inject it directly into the bloodstream through a vein. This also causes an almost immediate onset of effects.

Does Percocet show up in drug tests?

Many drug tests administered by law enforcement, parole officers, employers, and addiction treatment facilities test for opioids such as oxycodone in Percocet. For example, the urine drug tests required by the U.S. Department for Transportation (DOT) and the Department of Defence for employees search for traces of oxycodone use.[3]

However, some more basic five-panel drug tests only look for opiates (drugs directly derived from the poppy plant like heroin and codeine) and will miss semi-synthetic opioids such as oxycodone.[4]

If oxycodone is one of the substances tested for, the detection window—the amount of time after use that it can be detected—depends on the type of testing.

Urine tests

Urine drug tests are the most common type. Usually, they test for oxycodone and its metabolites, including noroxycodone and oxymorphone. These can usually be detected for two to four days after the last use.[5][6]

Saliva tests

Substances easily diffuse between the bloodstream and saliva, potentially making saliva testing a simple and accurate way to measure oxycodone use.[7] Oxycodone and its metabolites can be detected in saliva for up to 48 hours after last use.[8]

Blood tests

Blood testing is the least popular method of drug screening because it has a short detection window and is invasive. However, it can return results in minutes, while urine testing can take several days. Blood testing is most commonly performed in medical settings, such as when a patient arrives having suffered a suspected overdose.

In general, oxycodone can be detected in the blood for around 24 hours; however, small traces of metabolites may linger for a few more hours, and sensitive testing may pick them up.

Hair tests

Metabolites of oxycodone circulating in the body will be incorporated into hair strands as they grow. Within five to ten days of use, that part of the hair stand will reach the surface of the scalp and can be subjected to hair follicle testing.

In a typical hair follicle test, a strand of head hair will be pulled and the top 1.5 inches from the scalp will be analyzed. As head hair grows at an average rate of 0.5 inches per month, the detection window for this form of drug testing is around three months or 90 days.

Related: How long do drugs and alcohol stay in your system?

What affects how long Percocet stays in your system?

Our bodies metabolize and excrete drugs at different rates. The length of time Percocet remains in your system depends on a variety of factors, including:

  • Age: As we age, our metabolism of drugs slows. In adults over 65, the elimination of oxycodone is reduced and blood concentrations are 15% higher than in younger adults.[9]

  • Gender: women may metabolize oxycodone slower than men. Studies have shown that plasma oxycodone concentrations are 25% higher in female subjects than in males.[10]

  • Liver and kidney function: Oxycodone is metabolized by the liver, and in patients with advanced liver disease, the half-life was increased to an average of 14 hours, with a range of 6.4 to 24.6 hours. This means the starting doses in patients with liver function impairment should be reduced by 30% to 50%.[11] Impaired renal function will also slow the metabolism of oxycodone.

  • How long you’ve been taking oxycodone: After extended use, Percocet will build up in your body and will be detectable for a longer period of time after your last dose.

  • Dose: the more oxycodone you’ve consumed, the longer it will take for it to be totally eliminated. Read here for more info on Percocet dosage.

  • Other medication: many other medications are metabolized by the same enzymes as oxycodone. Your body has a limited supply of these enzymes, so the metabolism of both drugs will be slowed. Some drugs outright inhibit this metabolism. For example, common SSRI antidepressants fluoxetine and paroxetine inhibit the liver enzyme that metabolizes oxycodone and have been linked to an elevated risk of opioid overdose.[12]

Percocet overdose

An overdose of Percocet can be extremely dangerous, even fatal.

First, taking too much oxycodone can cause an opioid overdose, which requires immediate medical attention.

Symptoms of opioid overdoses include:[13]

  • Slow and shallow breathing

  • Deep drowsiness, inability to speak, unconsciousness

  • Blue or gray skin, dark lips and fingernails

  • Snoring or gurgling

The amount of Percocet and oxycodone that can cause overdose depends on the individual, their body weight, and experience with/tolerance for opioids. In general, daily opioid doses above 50 morphine milligram equivalent (MME)—or 33mg of oxycodone—are associated with an elevated risk of overdose.[14]

Opioid overdoses can be reversed through naloxone (Narcan), which lay people can be trained to administer, and anyone who uses opioids, either recreationally or as prescribed, should have them on hand.

You can also overdose on the acetaminophen component of Percocet. Taking more than 4g of acetaminophen a day—the amount in 12 Percocet pills—can cause severe liver damage. If you’re simultaneously drinking alcohol, just half that amount—2g of acetaminophen or 6 Percocet—can damage your liver.

Symptoms of acute liver failure include:[15]

  • Jaundice (yellow skin and whites of the eyes)

  • Pain in the upper right abdomen, the location of your liver

  • Ascites (swollen abdomen)

  • Nausea and vomiting

  • Malaise

  • Disorientation, confusion

  • Drowsiness

  • Musty or sweet-smelling breath

  • Tremors

Can you get Percocet out of your system quickly?

In general, you can’t speed up your body’s metabolism of a drug. Methods that purport to speed up the elimination, such as drinking large volumes of water, are both dangerous and ineffective. The only surefire way to remove traces of Percocet from your system is to stop taking the drug—taking precautions to avoid withdrawal symptoms—and seek help if you’re struggling to stay abstinent.

Percocet addiction treatment

Around three million Americans struggle with addictions to opioids, including Percocet.[16] Many were initially prescribed Percocet for legitimate reasons but developed physical or psychological dependence or felt they had to keep taking it to manage chronic pain or avoid uncomfortable withdrawal symptoms. 

Opioid use disorder can damage your health, relationships, and life plans, but it is treatable, usually with a combination of therapy, medication such as opioid replacements or antagonists, group meetings, and holistic treatments.