A single 5 mg dose of THC will typically clear your system within 3 to 4 days for a standard urine drug test, though it can be undetectable in as little as 1 to 2 days for lean, well-hydrated individuals. The exact window depends on your body composition, metabolism, and which type of test you’re facing. Five milligrams is a low dose (the standard amount in many commercial edibles), so your detection window is significantly shorter than what frequent users experience.
Detection Windows by Test Type
Different drug tests look for THC in different bodily fluids, and each has its own detection window. After a single 5 mg dose, here’s roughly what to expect:
- Urine: 1 to 4 days. Urine tests don’t actually measure THC itself. They measure a byproduct your liver produces when it breaks THC down. That byproduct peaks in urine about 9 hours after an oral dose, then gradually drops. For a one-time, low-dose user, levels usually fall below the testing threshold within a few days.
- Blood: 2 to 24 hours. Blood tests detect active THC, and after a single use, levels drop quickly. Low but measurable amounts (1 to 2 ng/mL) can linger for up to 8 hours without any signs of impairment.
- Saliva: Up to 24 hours. Oral fluid tests have the shortest window and are mainly used to detect very recent use.
- Hair: Up to 90 days in theory, but a single 5 mg dose often doesn’t deposit enough THC in hair follicles to trigger a positive result. Hair tests are designed to catch patterns of repeated use.
What Drug Tests Actually Measure
Standard workplace urine tests, including those required by the Department of Transportation, use a two-step process. The initial screening flags any sample at or above 50 ng/mL of THC metabolites. If that threshold is met, a confirmation test checks for 15 ng/mL. A single 5 mg edible in an occasional user produces metabolite concentrations well below what chronic use generates, which is why the detection window stays short.
These cutoff levels haven’t changed recently. Despite ongoing discussions about marijuana rescheduling, DOT regulations still treat marijuana as a prohibited substance for safety-sensitive positions, and the testing thresholds remain the same as of 2025.
Why Body Fat Matters More Than You’d Expect
THC is fat-soluble, meaning your body stores it in fatty tissue rather than flushing it out in water. After you consume an edible, THC gets absorbed through your digestive system, processed by your liver, and partially tucked away in fat cells. Over the following hours and days, those fat cells slowly release the stored THC back into your bloodstream, where your liver finishes breaking it down.
For a one-time 5 mg dose, this storage effect is minimal. There simply isn’t much THC to store. But your body fat percentage still influences how quickly you clear it. Someone with a lower body fat percentage will generally eliminate THC faster than someone with more adipose tissue, even at the same dose. This is one reason two people can take the same edible and have meaningfully different detection windows.
Edibles vs. Smoking at 5 mg
The way you consume THC changes how your body processes it. When you eat a 5 mg edible, THC passes through your liver before entering your bloodstream. This “first pass” metabolism converts a significant portion of THC into its metabolites right away, which means the metabolite that urine tests detect builds up faster and peaks later (around 9 hours) compared to smoking.
Smoked or vaped THC enters your bloodstream through your lungs almost immediately, producing a faster spike in blood THC levels but a somewhat different metabolite curve. In practical terms, the total detection window for a 5 mg dose is similar regardless of method, but edibles may produce a slightly more gradual rise and fall in urine metabolite levels.
Factors That Shorten or Extend Detection
Beyond body fat, several other variables affect how long 5 mg of THC stays detectable:
- Metabolism: People with faster metabolic rates break down THC more efficiently. Regular exercise, younger age, and higher muscle mass all contribute to faster clearance.
- Hydration: Staying well-hydrated dilutes the concentration of metabolites in your urine, which can push borderline results below the cutoff. This doesn’t speed up actual elimination, but it can affect whether a test reads positive or negative.
- Frequency of use: This is the single biggest factor. A truly occasional user (once a month or less) will clear 5 mg far faster than someone who uses cannabis a few times a week. THC accumulates in fat tissue with repeated use, and the metabolite’s half-life in urine averages around 30 hours but can stretch longer with buildup. Frequent users can test positive for 5 to 13 days or more, even after stopping completely.
- Genetics: Your liver enzymes determine how efficiently you metabolize THC. Some people are naturally faster metabolizers, and there’s no practical way to change this.
Realistic Timeline for Occasional Users
If you took a single 5 mg edible and you don’t use cannabis regularly, here’s a realistic timeline. Within 2 to 4 hours, THC levels in your blood will begin declining. By 24 hours, blood and saliva tests will almost certainly come back negative. Urine metabolite levels will peak around 9 hours after ingestion and then decline steadily. Most occasional users will pass a standard 50 ng/mL urine screen within 2 to 3 days, though it could take up to 4 days in some cases.
If you’re facing a test with a lower cutoff (15 ng/mL confirmation threshold, or a more sensitive employer panel), add an extra day or two to be safe. And if you’ve used cannabis even a handful of times in the weeks leading up to that 5 mg dose, your stored THC from previous sessions can extend the window beyond what a single-dose estimate would suggest.