While it’s possible to roughly estimate how long Demerol may stay in the system and how long it can be detected, time frames can still vary from person to person.

Article at a Glance:

Demerol is a brand-name opioid that is also sold under the generic name meperidine.

Demerol can be found in the urine for up to two days, and its breakdown product can be found in urine for up to four days.

Demerol can also be found in your blood, saliva and hair.

Demerol Showing up on Drug Tests

Demerol, a brand-name version of meperidine, is a prescription opioid medication used to treat pain. Demerol can be detected by drug tests, but the detection time varies depending on the type of drug test being used. The following provides an overview of how long Demerol stays in the system and factors that can affect detection times.

How Long Does Demerol Stay in Your Urine, Hair and Blood?

The detection time frame for Demerol can vary widely based on which drug test is administered. Average time frames for different tests include:

  • Urine: Demerol itself can be found in urine for up to two days. However, its breakdown product normeperidine can be found in urine for up to four days.
  • Hair: Demerol can be found in a typical half-inch hair sample for up to 90 days after the last dose.
  • Blood: Demerol can be found in blood for up to five hours after the last dose. However, normeperidine can be found in blood for up to 24 hours.
  • Saliva: Demerol can be found in saliva for up to two days after the last dose.

Half-Life of Demerol

The half-life of a drug is how long it takes for your body to clear half of the substance. It typically takes five half-livesfor a drug to completely leave your body.

Demerol’s half-life ranges anywhere from three to eight hours. However, its breakdown product normeperidine has a much longer average half-life of 20.6 hours. This means that meperidine can stay in the body for up to 40 hours, and normeperidine can stay in the body for more than 100 hours.

Factors That Influence How Long Demerol Stays in Your System

While it’s possible to roughly estimate how long Demerol may stay in the system, time frames can still vary from person to person. Factors that can influence how long Demerol stays in the system include:

  • Age: People aged 45 or older typically excrete drugs from their systems more slowly than younger people.
  • Kidney and liver health: People with kidney or liver problems can have a harder time metabolizing and eliminating drugs like Demerol.
  • Frequency of use: Demerol can accumulate in the system of a patient. If someone uses Demerol often, it may take longer for the drug to leave their system.
  • Other substances: Other substances, including alcohol, drugs and even certain foods and drinks, can make Demerol stay in the system longer. This is because Demerol has some drug interactions that can make it last longer in the body.

Demerol Prescription Facts

Demerol is intended to treat moderate to severe pain and be used on an as-needed, short-term basis. The drug is about 10 times weaker than morphine.

Experts often recommend avoiding Demerol for pain relief due to an increased risk of side effects, especially in older adults. Because Demerol carries the risk of psychological and physical dependence, doctors should go over a patient’s substance use history before prescribing it.

Drug PropertiesDemerol
Generic NamesMeperidine
Type of pain it can treatPain severe enough to require an opioid
Short-acting or long-actingShort-acting (every three to four hours)
Drug typeOpioid
Drug ScheduleSchedule II controlled substance
Side EffectsMood changes, constipation, tremor, seizure, slowed breathing
How long it takes to start working (oral route)Within 15 minutes
How long it takes to have its peak effect (oral route)Within one to 1.5 hours
Duration of effect (oral route)Up to four hours

Demerol Regulations

Like most prescription opioids, Demerol is a Schedule II controlled substance in the U.S. This means the drug has approved medical uses but also a high likelihood of severe misuse and dependence.

Physicians and pharmacists are warned to be careful when prescribing or dispensing this controlled substance — it is often sought by people with addiction and those who wish to divert it from medical use. Using Demerol without a prescription or in ways other than prescribed is illegal because it’s a controlled substance.

How Demerol Affects the Brain and Body

As an opioid painkiller (analgesic), Demerol changes the way the brain responds to pain. When the brain’s response to pain changes, the brain sends messages to the body that alter how the body experiences pain as well. Some people may also experience a euphoric feeling because opioids can trigger a release of dopamine into the brain and body. This can cause a reward and reinforcement response to begin, leading to the development of an addiction.

Demerol and other opioids also slow the central nervous system. This can cause people to feel drowsy, relaxed or even sedated. It can also cause a slowdown in essential functions, including heart rate and breathing.

If you or someone you love is struggling with opioid addiction, The Recovery Village is here to help. Contact us today to find out about opioid addiction treatment programs that can work well for your situation.

Jonathan Strum
Editor – Jonathan Strum
Jonathan Strum graduated from the University of Nebraska Omaha with a Bachelor's in Communication in 2017 and has been writing professionally ever since. Read more
Jessica Pyhtila
Medically Reviewed By – Dr. Jessica Pyhtila, PharmD
Dr. Jessica Pyhtila is a Clinical Pharmacy Specialist based in Baltimore, Maryland with practice sites in inpatient palliative care and outpatient primary care at the Department of Veteran Affairs. Read more
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Institute for Safe Medication Practices Canada. “Meperidine (Demerol®) safety issues.” 2005. Accessed September 14, 2021.

Global Library of Women’s Medicine. “Meperidine hydrochloride (pethidine hydrochloride).” Accessed September 14, 2021.

Medical Disclaimer

The Recovery Village aims to improve the quality of life for people struggling with substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare providers.