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How Long Does Demerol Stay in Your System?

The effects of Demerol are typically experienced within minutes and can last up to three hours.[1] However, traces of Demerol can remain in your system for much longer.

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Demerol can be detected in your urine for several days following last use, while it can be detected via a hair test for up to three months. Various factors — such as age, amount of Demerol consumed, general health, and personal metabolism — can impact how long Demerol remains in your system. 

Demerol Effects: How Long Do They Last? 

The effects of Demerol (meperidine) are felt quickly, and they dissipate quickly. 

An initial dose of 25 to 50 mg is recommended to be delivered over one to two minutes. Initial effects are felt within three to six minutes, with a peak of pain relief at six to seven minutes. The total duration of the effects of Demerol may be felt for approximately one to three hours.[1]

Common side effects of Demerol include the following:[2] 

  • Lightheadedness and dizziness
  • Weakness
  • Headache 
  • Nausea and vomiting
  • Sense of calm
  • Mood changes 
  • Stomach pains or cramps
  • Constipation 
  • Dry mouth
  • Flushing and sweating
  • Changes in vision 

Less common but more serious side effects can also occur and be symptoms of an opioid overdose. Signs of an overdose, including difficulty breathing, extreme sleepiness, being unresponsive or unable to wake up, cold, clammy skin, and slowed heartbeat, among others, require immediate medical attention.[2] Opioid overdose can be fatal.

Demerol Detection Timeline

The ability to detect Demerol in someone’s system varies depending on the type of test being used. Detection times vary from one to 90 days, depending on the test type. 

Standard opioid drug tests may not test for the presence of meperidine. To test for meperidine, specific drug tests must be ordered.[3] 

Below are average detection timelines of Demerol in the body based on the type of drug test used:[1-4]

Type of TestDetection Time
UrineSeveral days 
BloodWithin 24 hours
Saliva24–48 hours 
HairUp to 90 days 

Common Tests Used to Detect Demerol in Your System

There are multiple types of tests available to test for opioids like Demerol in someone’s system. You may be asked to take a drug test for employment purposes, as part of a treatment program, or for legal reasons. 

Common types of drug tests used to detect Demerol include the following:[4]

  • Urine: A clean urine sample is collected in a container. A testing professional may or may not have to be present to ensure the validity of the urine sample. 
  • Blood: A healthcare professional collects a blood sample from a vein in your arm. In less than five minutes, the sample is collected into a vial that is sent in for testing. 
  • Saliva: A healthcare professional places a swab or absorbent pad inside your cheek and leaves it there for a few moments to allow saliva to collect on the swab. Alternatively, your spit may be collected in a tube.
  • Hair: A hair sample is collected and tested for the presence of various substances. Unlike the other forms of drug tests, hair samples can contain traces of substances for a much longer period, often up to three months. 

The Half-Life of Demerol

The half-life of Demerol is two to five hours, while the half-life of normeperidine, an active metabolite of meperidine, is 15 to 30 hours. This means that it can take up to 10 hours for meperidine to be fully metabolized from one’s body or up to 60 hours for normeperidine.[6]

The half-life of Demerol also varies depending on how it is consumed. Demerol ingested orally or via intramuscular injection has a half-life of approximately two to five hours. When injected intravenously, the half-life is typically shorter, at approximately two to three hours for half of the drug to be eliminated from your body.[5]

Factors That Affect How Long Demerol Stays in Your Body

How long Demerol stays in your body ranges among individuals due to a variety of factors. Age, health, and individual response to the medication all impact how quickly it is processed in the body. 

Factors that affect how long Demerol stays in your body include the following:[6,7]

  • Age: Studies have found that infants given meperidine exhibited a half-life of 10.7 hours, which reduced to the average three-hour half-life as seen in adults, by the age of 8.
  • Health conditions: Certain health conditions, such as renal impairment, can cause Demerol to stay in your system for up to 40 hours. 
  • Quantity consumed: The amount of Demerol consumed affects how long it can be detected in your body. The more you consume, the longer it is likely to appear on a drug test.
  • Duration of use: How long you have been using Demerol can also impact how long it stays in your body and how likely you are to test positive for the substance. A prolonged history of use may mean Demerol stays in your system longer as well. 
  • Metabolism: How your body reacts to Demerol, including how quickly it metabolizes the drug, varies among individuals. Someone with a quick metabolism may process the drug faster than an individual with a slower metabolism who does not react to Demerol as well.

A Quicker Onset of Action

Demerol begins working faster than other opioids like morphine, but its effects do not last as long. However, that does not mean it is processed from your body faster than other opioids. 

Demerol poses a particular risk of overdose, as its effects weaken quickly, though the drug remains in the individual’s system. Taking more Demerol while there is still some of it in the body greatly increases the risk of overdose and other dangerous health effects. 

Always take care when taking Demerol or any other opioid, as the risk for overdose is always present. If you’ve been misusing Demerol and are unable to stop, reach out for help. 

Updated May 7, 2024
  1. Medications. Society of Gastroenterology Nurses and Associates. Accessed September 5, 2023.
  2. Meperidine. MedlinePlus: National Library of Medicine. Published May 15, 2023. Accessed September 6, 2023.
  3. Meperidine Drug Test. National Drug Screening, Inc. Accessed September 6, 2023.
  4. Opioid Testing. MedlinePlus: National Library of Medicine. Published December 15, 2020. Accessed September 6, 2023.
  5. Hallare J., Gerriets V. Half Life. StatPearls: National Library of Medicine. Published June 2023. Accessed September 6, 2023.
  6. Buck M. Is meperidine the drug that just won’t die? The Journal of Pediatric Pharmacology and Therapeutics. 2011;16(3):167-169. doi:10.5863/1551-6776-16.3.167
  7. Drug testing. MedlinePlus: National Library of Medicine. Published June 7, 2022. Accessed September 6, 2023.
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