From the Guidelines
You should wait at least 4 days to retest for methamphetamine after a positive urine drug screen (UDS) result, as the drug can continue to test positive for 2 to 4 days after consumption 1. When considering retesting after a positive result, it's essential to understand the factors that influence the elimination of methamphetamine from the body.
- The frequency and amount of methamphetamine use can impact how long the drug remains detectable in the urine.
- Individual factors such as metabolism, hydration level, body mass, and overall health can also affect the rate of elimination.
- According to the 2021 guideline for the evaluation and diagnosis of chest pain 1, a person's urine typically tests positive for methamphetamine within 1 to 4 hours of consuming the drug and will continue to test positive for 2 to 4 days. While methods like drinking plenty of water, exercising, and maintaining good nutrition may support overall health, they are unlikely to significantly speed up the elimination of methamphetamine from the body. In real-life clinical practice, prioritizing honesty about substance use, especially for employment or legal purposes, is crucial rather than attempting to manipulate test results.
From the FDA Drug Label
The biological half-life has been reported in the range of 4 to 5 hours. Approximately 62% of an oral dose is eliminated in the urine within the first 24 hours with about one-third as intact drug and the remainder as metabolites.
Based on the information provided, it is not possible to determine a specific waiting period to retest after a positive urine drug screen (UDS) for methamphetamine. The biological half-life of 4 to 5 hours and elimination of approximately 62% of the dose in the urine within 24 hours do not directly answer the question of how long to wait to retest. 2
From the Research
Urine Drug Screen (UDS) Retest Waiting Period for Methamphetamine
- The waiting period for retesting after a positive urine drug screen (UDS) for methamphetamine can vary depending on several factors, including the dose and route of administration, metabolism, and characteristics of the screening and confirmation assays 3.
- Studies have shown that methamphetamine can be detected in urine for up to 7 days after administration, with peak concentrations reached within 4-6 hours and declining thereafter 4.
- Another study found that amphetamine and methamphetamine could be detected in urine for up to 121 and 143 hours, respectively, after administration of the drug famprofazone, which is metabolized to these compounds 5.
- The detection time of methamphetamine in urine can also depend on the cutoff value used, with higher cutoff values resulting in shorter detection times 3.
- In general, it is recommended to wait at least 7-10 days after a positive UDS result for methamphetamine before retesting, as this allows for the majority of the drug to be eliminated from the body 4, 6.
- However, the exact waiting period may vary depending on individual factors, such as metabolism and drug use history, and should be determined on a case-by-case basis 7.
Factors Influencing Detection Time
- Dose and route of administration: Higher doses and certain routes of administration (e.g. intravenous) can result in longer detection times 3.
- Metabolism: Individual differences in metabolism can affect the rate at which methamphetamine is eliminated from the body 4.
- Characteristics of the screening and confirmation assays: The sensitivity and specificity of the assays used can impact the detection time of methamphetamine in urine 3.