A single 5 mg dose of THC clears your bloodstream within roughly a day if you rarely use cannabis, but its metabolites can linger in urine for two to four days and in body fat for considerably longer. The exact timeline depends on whether you ate the THC or inhaled it, how often you use cannabis, your body composition, and which type of drug test you face. Those variables create a surprisingly wide range of answers to what seems like a simple question.
What Happens to 5 mg of THC After You Take It
Once THC reaches your liver, most of it is converted into two main breakdown products: 11-OH-THC (the active metabolite that also produces a high) and 11-COOH-THC (an inactive metabolite that drug tests look for).1PubMed Central. Mechanisms of Action and Pharmacokinetics of Cannabis THC itself is fat-soluble, so a portion of it gets pulled out of your blood and tucked into fatty tissue rather than being broken down immediately. In animal studies, THC concentration in fat was roughly ten times greater than in any other tissue and persisted there for about two weeks after a single dose.2PubMed. Delta-9-tetrahydrocannabinol: localization in body fat That fat-storage effect is the main reason detection timelines stretch far beyond the hours you actually feel anything.
The route of consumption also matters. When you eat a 5 mg edible, THC has to pass through your digestive tract and liver before reaching your bloodstream. This “first-pass” metabolism converts a large chunk of the THC into metabolites before it ever circulates. The result is lower peak blood THC levels compared to smoking the same amount. In a study where participants consumed edibles averaging about 7.3 mg of THC, mean blood THC reached only about 2.8 ng/mL at two hours after eating.3Springer Nature (Journal of Cannabis Research). The effect of cannabis edibles on driving and blood THC For a 10 mg oral dose, peak blood THC was around 1 ng/mL in whole blood, and the total detection window stretched from zero to 22 hours.4Oxford University Press / Journal of Analytical Toxicology. Pharmacokinetic Profile of Oral Cannabis in Humans: Blood and Oral Fluid Disposition and Relation to Pharmacodynamic Outcomes A 5 mg dose would produce even lower peak levels and a somewhat shorter window, though the exact numbers have not been as tightly studied for oral dosing at that specific amount.
Detection Windows for Different Test Types
The question “how long does it stay in your system” really means “how long can a test find it,” and that answer changes dramatically depending on what kind of sample is being tested. Each test type looks for different compounds in different biological fluids, and each has its own detection threshold.
Blood
Blood tests measure THC itself, not just its metabolites, so they have the shortest detection window. After inhaling cannabis, blood THC levels spike within minutes and then drop off relatively quickly. After eating it, the peak is lower and more gradual. Blood THC levels are far lower after ingestion than after inhalation.5PubMed Central. Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis For an occasional user who takes 5 mg orally, THC is typically undetectable in blood within 12 to 22 hours. A frequent user is a different story: some heavy users showed residual blood THC as high as 12.3 ng/mL before they even smoked their study-session joint, simply because their baseline had not cleared from prior days of use.6Journal of Analytical Toxicology. Comparison of Cannabinoid Pharmacokinetic Properties in Occasional and Heavy Users Smoking a Marijuana or Placebo Joint
Urine
Urine tests are the most common type used by employers, and they do not look for THC itself. They detect THC-COOH, the inactive metabolite your liver produces as it breaks THC down. In one study that administered 5 mg of THC intravenously to both frequent and infrequent users, THC-COOH was tracked in urine for up to 12 days.7Journal of Analytical Toxicology. Metabolism of Tetrahydrocannabinol in Frequent and Infrequent Marijuana Users That 12-day figure represents how long the metabolite was measurable at all, not necessarily how long it would trigger a positive on a standard workplace screening. Most workplace urine tests use a cutoff of 50 ng/mL, and at that threshold a single low dose in an infrequent user typically clears in one to three days. When a lower cutoff of 15 ng/mL is used, a single smoked dose showed mean detection times of about 34 hours for a lower-potency cigarette and roughly 89 hours for a higher-potency one.8Journal of Analytical Toxicology. Urinary Excretion Profiles of 11-Nor-9-Carboxy-Δ9-Tetrahydrocannabinol in Humans after Single Smoked Doses of Marijuana At the standard 50 ng/mL cutoff, a one-time 5 mg edible in a non-regular user would be expected to clear urine in roughly one to two days, though individual variation can push that out.
Oral Fluid (Saliva)
Saliva tests detect THC itself and are gaining popularity for roadside testing. The peak concentration in saliva occurs during or immediately after consumption, largely because of direct contact between cannabis and the lining of your mouth rather than from THC circulating in your blood.9PubMed Central. Cannabinoid disposition in oral fluid after controlled smoked, vaporized, and oral cannabis administration For a 10 mg oral dose, THC was detectable in saliva for up to 22 hours.4Oxford University Press / Journal of Analytical Toxicology. Pharmacokinetic Profile of Oral Cannabis in Humans: Blood and Oral Fluid Disposition and Relation to Pharmacodynamic Outcomes Edibles tend to produce lower saliva concentrations than smoked or vaped cannabis because there is less direct oral contact with the plant material.
Breath
Breath testing for cannabis is still emerging, but research shows THC can be detected in exhaled breath for at least three hours after smoking a single cannabis cigarette.10Journal of Breath Research. Drug detection in breath: non-invasive assessment of illicit or pharmaceutical drugs In one study, all 44 participants tested positive in breath within the first hour after smoking, with THC showing a very short half-life in breath of about one to 19 minutes.11PubMed Central. A comprehensive breath test that confirms recent use of inhaled cannabis within the impairment window Breath tests are designed to catch very recent use, which makes them appealing for law enforcement but means they have the narrowest detection window of any method.
Hair
Hair tests can theoretically detect cannabis use going back 90 days, since metabolites get deposited in the hair shaft as it grows. But for low-dose, infrequent use, hair testing is unreliable. Research comparing hair cannabinoid levels with self-reported use found that hair tests work well for identifying heavy users but fail to reliably catch light or moderate use.12PubMed Central. Comparison of cannabinoids in hair with self‐reported cannabis consumption in heavy, light and non‐cannabis users If you used a single 5 mg edible, a hair test is unlikely to flag it.
Why Frequent Users Face Much Longer Timelines
The biggest single variable in detection time is how often you use cannabis. If you consume it daily or near-daily, THC accumulates in your fat tissue faster than your body can clear it. Each new dose adds to the reservoir. That stored THC slowly leaks back into your bloodstream over days and weeks, keeping metabolite levels elevated in urine long after your last dose.
The pharmacokinetics bear this out starkly. In occasional users, THC’s elimination half-life after smoking was about one to six hours. In heavy users who were not given a new dose (the placebo arm of a study), the half-life stretched to 17 to 44 hours because their bodies were slowly releasing stored THC.6Journal of Analytical Toxicology. Comparison of Cannabinoid Pharmacokinetic Properties in Occasional and Heavy Users Smoking a Marijuana or Placebo Joint A chronic user’s apparent bioavailability of THC can be roughly two and a half times greater than an occasional user’s for the same dose, meaning they absorb and retain significantly more.13PubMed. Population pharmacokinetic model of blood THC and its metabolites in chronic and occasional cannabis users and relationship with on-site oral fluid testing For a daily user, even a modest 5 mg dose adds to an existing pool of THC that can keep urine tests positive for weeks after the last use.
Body Fat, Food, and Exercise
Because THC parks itself in fat, your body composition affects how long it lingers. More body fat means a larger storage depot and a longer clearance timeline. There is also an interesting wrinkle: burning fat can theoretically re-release stored THC back into your blood. Animal research demonstrated that lipolysis, the process of breaking down fat stores, enhanced the release of THC from fat back into the bloodstream.14PubMed Central. Reintoxication: the release of fat-stored delta(9)-tetrahydrocannabinol (THC) into blood is enhanced by food deprivation or ACTH exposure In regular human cannabis users, exercise did cause small but measurable increases in plasma THC, and those increases correlated with BMI: the higher the BMI, the bigger the spike.15Drug and Alcohol Dependence. Exercise increases plasma THC concentrations in regular cannabis users
That said, the practical effect for a one-time low-dose user appears to be minimal. A small study of lean cannabis users found that moderate exercise and short-term fasting did not produce meaningfully different urine cannabinoid levels, though the researchers noted that obese individuals could be more sensitive to this redistribution effect.16PubMed Central. Can Physical Exercise or Food Deprivation Cause Release of Fat-Stored Cannabinoids? In other words, going for a jog the day after a single 5 mg edible is not going to cause a surprise positive on a urine test. But for a heavy daily user who stops cold turkey and starts an intense exercise program, the redistribution of stored THC from fat into blood is a real phenomenon worth knowing about.
Food plays a role on the absorption side. Eating THC with a meal, especially one containing fat, substantially increases how much THC makes it into your bloodstream. In one human trial, mean peak plasma THC concentration was one to three times higher when participants took THC in a fed state compared to fasting.17PubMed. A phase I study to assess the effect of food on the single dose bioavailability of the THC/CBD oromucosal spray An animal study confirmed this, showing that co-administering THC with dietary fats increased systemic exposure by about 2.5 times.18PubMed Central. Dietary fats and pharmaceutical lipid excipients increase systemic exposure to orally administered cannabis and cannabis-based medicines So a 5 mg edible eaten on a full stomach after a fatty meal could behave more like a 10 to 12 mg dose in terms of what ends up circulating in your blood.
Genetic Differences in THC Metabolism
Not everyone’s liver breaks down THC at the same speed. The main enzyme responsible for metabolizing oral THC is called CYP2C9, and common genetic variants in this enzyme significantly alter how quickly you clear THC. People carrying two copies of the CYP2C9*3 variant had a threefold higher exposure to THC (measured as area under the curve) and about 70% less of the inactive metabolite THC-COOH compared to people without the variant. They also trended toward greater sedation from the same dose.19PubMed. Interindividual variation in the pharmacokinetics of Delta9-tetrahydrocannabinol as related to genetic polymorphisms in CYP2C9 This means that for a minority of the population, 5 mg hits considerably harder and stays in the blood longer, while potentially producing less of the urinary metabolite that standard drug tests detect. It is one reason two people can take the same dose and have very different experiences and detection outcomes.
As for sex-based differences, the picture is less dramatic than you might expect. A study comparing THC disposition in men and women found that the terminal-phase half-life of THC ranged from 25 to 36 hours in both sexes regardless of the route of administration, with no meaningful difference between them.20PubMed. Metabolism, disposition, and kinetics of delta-9-tetrahydrocannabinol in men and women There are some differences in which specific metabolites the liver produces, at least in animal models, but these do not appear to translate into significantly different detection timelines in humans.21Biochemical Pharmacology. Sex difference in the oxidative metabolism of Δ9-tetrahydrocannabinol in the rat Body fat percentage, which does tend to differ between sexes on average, probably matters more than sex itself.
When the High Ends Versus When the Test Clears
One of the more frustrating aspects of THC pharmacology is the mismatch between how long you feel impaired and how long a test can find evidence of use. For oral THC in infrequent users, subjective effects peaked around two hours after dosing and participants rated themselves as feeling “stoned” for up to eight hours, but no effects were detectable at 24 or 48 hours.22SpringerLink / Psychopharmacology. Cognitive and subjective dose-response effects of acute oral Delta 9-tetrahydrocannabinol (THC) in infrequent cannabis users Yet a urine test using a sensitive cutoff could still detect the metabolite days later. After inhaling cannabis, the disconnect runs the other direction: blood THC levels typically return to baseline well before subjective impairment fades.5PubMed Central. Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis
This disconnect is central to the debate over cannabis-related driving laws and workplace testing. A positive urine test after a weekend edible says nothing about whether you are impaired at work on Monday. And a blood test that shows you are below the legal driving limit does not necessarily mean you are safe to drive, especially shortly after inhalation. Neither test type reliably measures real-time impairment, which is why breath testing is attracting interest as a tool that might track a narrower “impairment window.” Current breath research shows that THC in exhaled air has such a short half-life that it essentially only flags use within the past hour or two.11PubMed Central. A comprehensive breath test that confirms recent use of inhaled cannabis within the impairment window
Secondhand Smoke and False Positives
People sometimes worry that being around cannabis smoke could trigger a positive drug test. Under extreme conditions it is technically possible, but the practical risk is very low. In a controlled study, non-smokers were placed in a small, unventilated room with cannabis smokers for an hour. At the standard 50 ng/mL urine cutoff, only a single participant produced a positive test, and positives were limited to the hours immediately following the exposure session. At more sensitive cutoffs like 20 ng/mL, multiple positives appeared.23PubMed Central. Non-Smoker Exposure to Secondhand Cannabis Smoke. I. Urine Screening and Confirmation Results The researchers concluded that while secondhand exposure can technically produce a positive result, it requires conditions that are obvious to anyone present, like hotboxing a sealed car. Walking through a cloud of smoke at a concert is not going to create a testing problem.
Another common question is whether drinking large amounts of water or using “detox” products can beat a urine test. One study compared two commercial detoxification products against simple water loading. Water alone was approximately as effective as the commercial products in reducing metabolite concentrations in urine specimens, but the effect on immunoassay screening results, the type of test most employers use, was minimal.24PubMed. Efficacy of two commercial products for altering urine drug test results Diluting your urine may lower the raw concentration of metabolites, but testing labs check for dilution by measuring creatinine levels. An excessively dilute sample often gets flagged and requires a retest, so aggressive water loading is a risky strategy.
Putting the Timeline Together for a One-Time 5 mg Dose
If you are an infrequent user who takes a single 5 mg edible, here is a reasonable picture of what to expect, keeping in mind that individual variation from genetics, body fat, and meal timing can shift these windows in either direction:
- Blood: THC peaks within one to three hours and drops below detection limits in roughly 6 to 16 hours, depending on the lab’s sensitivity threshold.
- Saliva: Detectable for up to about 12 to 22 hours, though edibles produce lower saliva levels than smoked cannabis.
- Urine: At the standard 50 ng/mL workplace cutoff, the metabolite THC-COOH typically clears in one to two days. At a 15 ng/mL cutoff, it may take up to three or four days.
- Breath: Only relevant for smoked or vaped cannabis; an edible would not produce significant breath THC.
- Hair: A single 5 mg dose is unlikely to be detected, as hair testing is unreliable for low-level use.
These estimates get thrown off in specific scenarios. Eating the edible with a high-fat meal could roughly double your blood levels. Carrying the CYP2C9*3 genetic variant could triple your THC exposure. And if you are actually a regular user who has not fully cleared prior doses, the 5 mg simply adds to whatever is already stored in your body, potentially keeping urine tests positive for a week or more beyond what an occasional user would experience.