How long does mop stay in your urine?

October 8, 2025 •

4 min read

According to Mayo Clinic Proceedings, morphine is typically detectable in urine for 48 to 72 hours following use. This timeframe for how long does mop stay in your urine can be influenced by multiple individual and pharmacological factors, making a definitive single answer difficult.

Quick Summary

Morphine, or MOP in drug testing, typically remains detectable in urine for 1 to 3 days after last use, but this window can be extended by factors such as dosage, frequency of use, and individual metabolism. The drug is processed in the liver and excreted through the kidneys, with its metabolites lingering in the system longer than its psychoactive effects.

Key Points

Standard Urine Detection: For occasional use, MOP (morphine) is typically detectable in urine for 1 to 3 days after the last dose.
Chronic Use Extends Detection: Heavy or frequent use can extend the detection window to 5-7 days or longer due to accumulation in the body.
Metabolites Remain Longer: The effects of morphine wear off in hours, but its metabolites can be detected in urine for several days.
Multiple Influencing Factors: Individual metabolism, hydration, age, and liver/kidney function all affect the exact detection time.
Detection Varies by Test Type: While urine tests have a relatively long window, blood tests have a short window (up to 12 hours), and hair follicle tests can detect use for up to 90 days.
Poppy Seeds Can Affect Results: Consuming large amounts of poppy seeds can cause a positive result for morphine on a urine test, though confirmatory testing can help differentiate the cause.

What is MOP on a Drug Test?

In the context of a drug test, 'MOP' is an acronym for Morphine, a powerful opioid analgesic derived from the opium poppy. It is often included in standard drug screening panels to detect the use of morphine itself or other opioids that metabolize into morphine, such as heroin. A positive MOP result on a urine test indicates that morphine or its metabolites are present in the sample at or above the test's cutoff level.

The Average Detection Window for MOP (Morphine) in Urine

The typical detection window for morphine in a urine drug test for a single, occasional use is 1 to 3 days, or 48 to 72 hours. It's crucial to understand that this is an average, and for individuals who use morphine more frequently or in higher doses, this timeframe can be significantly longer. For chronic or heavy users, morphine may be detectable for 5 to 7 days or more after the last dose.

How the Body Processes and Eliminates Morphine

To understand why morphine remains in the body long after its effects wear off, it's helpful to look at its pharmacological journey, known as pharmacokinetics.

Absorption and Distribution: After ingestion or injection, morphine is absorbed into the bloodstream. It's then distributed to various body tissues, including the brain, liver, and kidneys. Due to its relatively low fat solubility, it crosses the blood-brain barrier somewhat slowly, which influences its effects.
Metabolism: The liver is the primary site of morphine metabolism. Here, it is primarily conjugated with glucuronic acid to form two main metabolites: morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G). While M3G is largely inactive, M6G has notable analgesic activity.
Elimination: The final stage is excretion, primarily through the kidneys via urine. A small percentage (2-12%) of the original dose is excreted unchanged, but the majority is eliminated as the M3G and M6G metabolites. The presence of these metabolites is what drug tests detect for an extended period, long after the parent drug's effects have faded. The half-life of morphine is relatively short (1.5 to 4.5 hours), meaning it takes five half-lives for the drug to be purged from the bloodstream. However, the detection window is longer because tests can pick up lingering metabolites.

Factors That Influence Morphine Detection in Urine

The standard 1- to 3-day detection window for morphine is just an estimate. Several factors can either shorten or, more commonly, extend this period, leading to a surprising test result.

Dosage and Frequency: Higher doses and more frequent use lead to accumulation in the body, particularly for chronic users, extending the detection window.
Individual Metabolism: A person's metabolic rate, influenced by genetics, age, and health, determines how quickly their body processes and eliminates the drug.
Liver and Kidney Function: The liver is crucial for metabolizing morphine, and the kidneys for its excretion. Impaired function in either organ can significantly slow down elimination and prolong detectability.
Body Mass and Body Fat: Morphine is not stored in fat like THC (marijuana), so body mass has a less direct effect on detection time compared to other drugs. However, body composition can still play a role in overall metabolism.
Hydration Levels: Dehydration concentrates urine, potentially increasing the likelihood of a positive test, while over-hydration can dilute a sample and may be flagged by a lab.
Type of Formulation: The use of extended-release morphine formulations (like MS Contin) can lead to a longer detection period compared to immediate-release versions.

Comparison of Morphine (MOP) Detection Windows by Test Type


Test Type	Typical Detection Window	Key Features and Use Case
Urine Test	1 to 3 days (occasional use) to 5-7 days or more (heavy use)	Most common method for workplace and probation testing. Detects metabolites for a relatively long period.
Blood Test	Up to 12 hours (single dose)	Measures recent use and current impairment. Shorter detection window due to rapid metabolism.
Saliva Test	1 to 4 days	Convenient and non-invasive, used for roadside and workplace screening. Detects recent use.
Hair Follicle Test	Up to 90 days or longer	Offers the longest detection window by measuring drug metabolites in hair follicles. Used to determine long-term use patterns.

Conclusion

For those concerned about how long does mop stay in your urine, the standard answer is 1 to 3 days for occasional use, but this can extend considerably based on individual factors and the frequency of use. A urine test can detect morphine and its metabolites for longer than the psychoactive effects are felt because the drug and its byproducts are gradually processed and eliminated by the body. Given the wide range of factors influencing a drug test result, relying on average timelines is risky. Anyone with concerns about passing a drug test should consult with a medical professional or seek help for any potential substance use issues. For more detailed information on prescription and illicit substances, including detection times, the National Institutes of Health offers extensive resources.

Frequently Asked Questions

Yes, eating excessively large amounts of poppy seeds can result in morphine concentrations high enough to trigger a positive result on a urine drug test. Specialized confirmatory testing can help distinguish this from illicit use.

Morphine has a relatively short elimination half-life, typically reported to be between 1.5 and 4.5 hours. It takes approximately five half-lives for the drug to be fully purged from the system, but metabolites remain detectable longer.

Drug tests use an immunoassay to detect the presence of morphine and its metabolites. If the initial screen is positive, confirmatory testing, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), can be performed to provide a more definitive result.

The effects of morphine wear off relatively quickly compared to its detection time. For immediate-release formulations, the effects typically last between 4 and 6 hours.

While staying properly hydrated is part of good health, attempting to dilute a urine sample by drinking excessive water is not a reliable method for passing a drug test. It can lead to an invalid test result, which may be flagged by the lab.

Some medications, including certain cold medicines with pseudoephedrine, can potentially cause a false positive result for opioids on an initial screening test. Confirmatory testing is often used to prevent this issue.

The method of administration can impact how quickly the drug is absorbed and eliminated, but the overall detection window in urine remains consistent for most methods. Intravenous use, for example, results in a faster onset but doesn't drastically change the long-term excretion pattern of metabolites.