The short answer
After a single dose, amphetamine is detectable for about 12 to 48 hours in blood, 20 to 60 hours in oral fluid and 1 to 4 days in urine. Genuinely daily or dependent use is a different curve: 1 to 4 days in blood, up to about 7 days in saliva and 2 to 7.5 days in urine.
Two things drive that gap, and neither is the one people expect. The first is the frequency step — Clearhead does not grade amphetamine by "how many times a month" at all, it flips between a single-dose window and a daily-use window. The second is urine pH, which moves the plasma half-life from about 7 hours to about 34 hours in the same person.
How long is amphetamine detectable in blood, saliva and urine?
| Use pattern | Blood | Saliva | Urine (amphetamine class) |
|---|---|---|---|
| Single or episodic | 12–48 h | 20–60 h | 24–96 h (1–4 d) |
| Daily / dependent | 24–96 h (1–4 d) | 36–168 h (up to 7 d) | 48–180 h (2–7.5 d) |
These are the same windows Clearhead shows in the app, at these reference cutoffs: blood 20 ng/mL, oral fluid 25 ng/mL in the model (DRUID forensic 25 ng/mL, SAMHSA screening 50 ng/mL), urine 500 ng/mL (immunoassay screen). Estimates, not measurements.
Speed, dexamfetamine and Elvanse are one molecule to a test
Street speed, prescription dexamfetamine (Attentin) and lisdexamfetamine (Elvanse) all put the same molecule in front of an immunoassay — Adderall is the US brand name for the same class. The table above applies to every one of them. A prescription changes the legal reading of a positive result, because you can document it; it does not change the pharmacokinetics or shorten a window by an hour.
Street powder adds one extra uncertainty, and it is not about the window: purity varies enormously, so the dose you actually took is the unknown quantity. The detection window is far less sensitive to dose than people assume, which is why unknown purity moves the effect much more than it moves the table.
The urine-pH lever: about 7 hours or about 34 hours
Amphetamine is a weak base cleared largely unchanged by the kidney, so how acidic your urine is decides how much of it gets reabsorbed on the way out. The published spread is large: a plasma half-life of about 7 hours in acidic urine against about 34 hours in alkaline urine (de la Torre 2004). That is roughly a fivefold swing in the same person at the same dose, and it dwarfs every other individual factor here.
Clearhead publishes its windows at neutral urine pH — a half-life of about 10 hours, within the literature range of 6 to 12 hours — and flags the spread rather than modelling it numerically. That is why every figure on this page is a range rather than a deadline. Diet, antacids, hard exercise and illness all shift urine pH, so treat it as a source of variation, not as a lever to pull.
What moves the window — and what doesn't
Frequency, in the daily sense
The multi-day figures belong to genuinely daily or dependent use — the chronic oral-fluid tail comes from a detoxification cohort using roughly 0.5 to 2 g a day (Andås 2016). Between single-dose and full chronic, the estimate scales with the typical daily dose instead of jumping straight to the long number, so a small daily amount sits well below the 2-to-7.5-day urine window. Weekend use is not chronic use here: amphetamine is water-soluble and does not accumulate the way THC does.
Dose — weaker than you would think
A larger single dose starts higher on the same curve and buys hours, not days. For scale, a controlled 40 mg dose of d-amphetamine produced a plasma peak of about 120 ng/mL at roughly 3 hours (Dolder & Liechti 2017) — that is peak height, not a longer tail.
Route — changes the peak, not the clearance
Insufflation raises absorption and peak concentration; smoking raises both further. Neither touches the half-life, and neither moves the detection window. Amphetamine also concentrates in oral fluid at roughly 2.76 times the plasma level (Cone & Huestis 2007), which is why a swab picks it up at all.
Amphetamine and methamphetamine on the same panel
A standard panel carries separate AMP and mAMP lines, and a laboratory confirmation tells them apart cleanly. The complication runs in one direction only: about 7% of methamphetamine converts to amphetamine in the body (Cody 2002), so methamphetamine use lights up both lines, and the amphetamine signal appears later and lingers. Amphetamine on its own never produces methamphetamine, so an AMP-only result does not point back at meth.
The cutoff decides the window
"How long is it detectable" is unanswerable without "detectable at what threshold". The urine figures here assume a 500 ng/mL immunoassay screen. Oral fluid is the clearest illustration: the model uses 25 ng/mL, matching the DRUID forensic cutoff, while SAMHSA screening sits at 50 ng/mL — twice as high, and therefore a shorter window from the same sample. Any published number without its matrix and its cutoff is not comparable to any other.
Driving: amphetamine is a zero-tolerance drug across most of the EU
Unlike THC, where several countries legislate a numeric blood threshold, amphetamine is handled under zero-tolerance or near-zero-tolerance rules in most European jurisdictions: a confirmed presence in a roadside or blood sample is an offence in itself, with no legal quantity you are allowed to be under. Analytical confirmation limits exist in laboratory protocols, but they are technical thresholds, not permissions. To see how the numeric-limit approach works where it does exist, our THC limits by country page sets out the per-country picture for cannabis.
The timing mismatch cuts both ways. The comedown — exhaustion, poor attention, wrecked sleep — can impair driving long after blood levels have fallen under any cutoff, while a urine test can stay positive for days after every effect has ended. Neither the presence nor the absence of a positive result is a statement about your fitness to drive.
Frequently asked questions
How long does amphetamine stay in your system?
It depends on the matrix and on how often you use. After a single dose: roughly 12 to 48 hours in blood, 20 to 60 hours in oral fluid and 1 to 4 days in urine. Daily or dependent use stretches urine to about 2 to 7.5 days.
How long is amphetamine detectable in a urine test?
A standard immunoassay strip screens at 500 ng/mL and reads the whole amphetamine class — the parent drug plus its metabolites. That gives 1 to 4 days after a single dose and 2 to 7.5 days in daily or dependent use. These metabolites are water-soluble, so the window stays in days, not weeks.
Does a prescription for dexamfetamine or lisdexamfetamine change the window?
No. Attentin and Elvanse deliver the same molecule a test looks for, so the window is the same as for street speed — Adderall is the US brand name for the same class. What a prescription changes is the legal reading of a positive result, not the biology behind the window.
Why does urine pH matter so much for amphetamine?
Because amphetamine is a weak base excreted largely unchanged by the kidney. Acidic urine flushes it out, alkaline urine lets more of it be reabsorbed: the half-life runs from about 7 hours in acidic urine to about 34 hours in alkaline urine (de la Torre 2004). That is the single biggest swing factor.
Can a test tell amphetamine and methamphetamine apart?
A basic strip has separate AMP and mAMP lines, and a laboratory confirmation separates them cleanly. The catch runs one way: about 7% of methamphetamine converts to amphetamine in the body, so methamphetamine use trips both lines. Amphetamine on its own does not produce methamphetamine.
Does taking a bigger dose of speed lengthen the detection window?
Far less than how often you take it. Amphetamine is water-soluble and does not accumulate in fat the way THC does, so a single larger dose starts higher on the same curve and buys hours. The jump to a multi-day window comes from genuinely daily or dependent use.
Does drinking water or a detox product shorten the window?
No. Water, coffee, exercise and detox products do not change how fast the kidney clears amphetamine. Drinking large volumes before a urine test only dilutes the sample, and laboratories screen for exactly that with creatinine and specific-gravity checks — a diluted specimen is usually flagged.
Does a negative test mean amphetamine is no longer affecting me?
No. Detection and impairment are different questions. The comedown — exhaustion, poor attention, disrupted sleep — can affect you long after blood levels fall below any cutoff, and a urine test can stay positive days after every effect has ended. Most EU countries apply zero tolerance to amphetamine at the wheel.
Where these numbers come from
The windows above are the ones built into the Clearhead engine, each tied to a published source rather than to a round number copied between websites. The model carries a plasma half-life of about 10 hours as the neutral-pH central value, expresses the pH uncertainty as a range instead of a single hard figure, and applies the chronic windows only when someone marks genuinely daily or dependent use. You can read the wider approach on our methodology page.
Sources referenced by the model: Dolder PC & Liechti ME 2017, Front Pharmacol 8:617 (40 mg d-amphetamine, Cmax ~120 ng/mL, Tmax ~3 h) · de la Torre R et al. 2004 (volume of distribution ~4 L/kg, half-life 6–12 h, urine-pH dependence ~7 h acidic to ~34 h alkaline) · Cone EJ & Huestis MA 2007 (oral-fluid pharmacokinetics, saliva/plasma ratio ~2.76) · Verstraete AG 2004 (detection times across matrices) · Andås 2016, J Anal Toxicol (chronic high-dose use extended oral fluid to ~8 days; the amphetamine model tops out at 7.5 days) · Cody JT 2002 (methamphetamine to amphetamine conversion, ~7%) · SAMHSA / DHHS and DRUID (oral-fluid and urine cutoffs). Reviewed 2 September 2026.